Fertilizering Containerized Plants IV

12 years ago

This topic has proven to be a fairly popular addition to the Container Gardening forum, having reached the maximum number of posts allowed on three previous occasions, so I'll post it for its fourth go-round. Nutrient supplementation has been discussed frequently, but usually in piecemeal fashion, on this forum and forums related. Prompted originally by a question about fertilizers in another thread, I decided to collect a few thoughts & present an overview that will hopefully be seen as a simplification and found to be helpful.

Fertilizing Containerized Plants IVcolor>size>

Let me begin with a brief and hopefully not too technical explanation of how plants absorb water from the soil and how they obtain the nutrients/solutes that are dissolved in that water. Most of us remember from our biology classes that cells have membranes that are semi-permeable. That is, they allow some things to pass through the walls, like water and select elements in ionic form dissolved in the water, while excluding other materials like large organic molecules. Osmosis is a natural phenomenon that is nature's attempt at creating a balance (isotonicity) in the concentration of solutes in water inside and outside of cells. Water and ionic solutes will pass in and out of cell walls until an equilibrium is reached and the level of solutes in the water surrounding the cell is the same as the level of solutes in the cell.

This process begins when the finest roots absorb water molecule by molecule at the cellular level from colloidal surfaces and water vapor in soil gasses, along with the nutrient load dissolved in that water, and distribute water and nutrients throughout the plant. I want to keep this simple, so I'll just say that the best water absorption occurs when the level of solutes in soil water is lowest, and in the presence of good amounts of oxygen (this is where I get to plug a well-aerated and free-draining soil). Deionized (distilled) water contains no solutes, and is easiest for plants to absorb. Of course, since distilled water contains no nutrients, using it alone practically guarantees deficiencies of multiple nutrients as the plant is shorted the building materials (nutrients) it needs to manufacture food, keep its systems orderly, and keep its metabolism running smoothly.

We already learned that if the dissolved solutes in soil water are low, the plant may be well-hydrated, but starving; however, if they are too high, the plant may have a large store of nutrients in the soil but because of osmotic interference the plant may be unable to absorb the water and could die of thirst in a sea of plenty. When this condition occurs, and is severe enough (high concentrations of solutes in soil water), it causes fertilizer burn (plasmolysis), a condition seen when plasma is torn from cell walls as the water inside the cell exits to maintain solute equilibrium with the water surrounding the cell.

Our job, because we cannot depend on an adequate supply of nutrients being supplied by the organic component of a container soil as it breaks down, is to provide a solution of dissolved nutrients in a concentration high enough that the supply remains in the adequate to luxury range, yet still low enough that it remains easy for the plant to take up enough water to be well-hydrated and free of drought stress. Electrical conductivity (EC) of, and the level of TDS (total dissolved solids) in the soil solution is a reliable way to judge the adequacy of solute concentrations and the plant's ability to take up water. There are meters that measure these concentrations, and for most plants the ideal range of conductivity is from 1.5 - 3.5 mS, with some, like tomatoes, being as high as 4.5 mS. This is more technical than I wanted to be, but I added it in case someone wanted to search 'mS' or 'TDS' or 'EC'. Most of us, including me, will have to be satisfied with simply guessing at concentrations, but understanding how plants take up water and fertilizer, as well as the effects of solute concentrations in soil water is an important piece of the fertilizing puzzle.

Now, some disconcerting news - you have listened to all this talk about nutrient concentrations, but what do we supply, when, and how do we supply them? We have to decide what nutrients are appropriate to add to our supplementation program, but how? Most of us are just hobby growers and cannot do tissue analysis to determine what is lacking. We CAN be observant tough, and learn the symptoms of various nutrient deficiencies - and we CAN make some surprising generalizations.

What if I said that the nutritional needs of all plants is basically the same and that one fertilizer could suit almost all the plants we grow in containers - that by increasing/decreasing the dosage as we water, we could even manipulate plants to bloom and fruit more abundantly? It's really quite logical, so please let me explain.

Tissue analysis of plants will nearly always show NPK %s to be very close to an average ratio of approximately 10:1.5:7. If we assign N the constant of 100, P and K will range from 13-19 and 45-70 respectively. (I'll try to remember to make a chart showing the relative ratios of all the other essential nutrients plants normally take from the soil at the end of what I write.) All we need to do is supply nutrients in approximately the same ratio as plants use them, and at concentrations sufficient to keep them in the adequate to luxury range at all times.

Remember that we can maximize water uptake by keeping the concentrations of solutes low, so a continual supply of a weak solution is best. Nutrients don't often just suddenly appear in large quantities in nature, so the low and continual dose method most closely mimics the nutritional supply Mother Nature offers. If you decide to adopt a "fertilize every time you water" approach, most liquid fertilizers can be applied at 3/4 to 1 tsp per gallon for best results. If you decide that is too much work, try halving the dose recommended & cutting the interval in half. You can work out the math for granular soluble fertilizers and apply at a similar rate.

The system is rather self regulating if fertilizer is applied in low concentrations each time you water, even with houseplants in winter. As the plant's growth slows, so does its need for both water and nutrients. Larger plants and plants that are growing robustly will need more water and nutrients, so linking nutrient supply to the water supply is a win/win situation all around.

Another advantage to supplying a continual low concentration of fertilizer is, it eliminates the tendency of plants to show symptoms of nutrient deficiencies after they have received high doses of fertilizer and then been allowed to return to a more favorable level of soil solute concentrations. Even at perfectly acceptable concentrations of nutrients in the soil, plants previously exposed to high concentrations of nutrients readily display deficiency symptoms, even at normal nutrient loads.

You will still need to guard against watering in sips, and that habit's accompanying tendency to ensure solute (salt) accumulation in soils. Remember that as salts accumulate, both water and nutrient uptake is made more difficult and finally impaired or made impossible in severe cases. Your soils should always allow you to water so that at least 10-15% of the total volume of water applied passes through the soil and out the drain hole to be discarded. This flushes the soil and carries accumulating solutes out the drain hole.

I use a liquid fertilizer with a full compliment of nutrients and micronutrients in a 3:1:2 ratio. Note that 'RATIO' is different than NPK %s. Also note how closely the 3:1:2 ratio fits the average ratio of NPK content in plant tissues, noted above (10:1.5:7). If the P looks a little high at 4, consider that in container soils, P begins to be more tightly held as pH goes from 6.5 to below 6.0, which is on the high side of most container soil's pH, so the manufacturer probably gave this some careful consideration. Also, P and K percentages shown on fertilizer packages are not the actual amount of P or K in the blend. The percentage of P on the package is the percentage of P2O5 (phosphorous pentoxide) and you need to multiply the percentage shown by .43 to get the actual amount of P in the fertilizer. Similarly, the K level percentage shown is actually the level of K2O ( potassium oxide) and must be multiplied by .83 to arrive at the actual amount of K supplied.

To answer the inevitable questions about specialty fertilizers and "special" plant nutritional requirements, let me repeat that plants need nutrients in roughly the same ratio. 'RATIO' is also an entirely a separate consideration from dosage. You'll need to adjust the dosage to fit the plant and perhaps strike a happy medium in containers that have a diversity of material.

If nutrient availability is unbalanced - if plants are getting more than they need of certain nutrients, but less than they need of others, the nutrient they need the most will be the one that limits growth. There are 6 factors that affect plant growth, vitality and yield; they are: air, water, light, temperature, soil or media and nutrients. Liebig's Law of Limiting Factors states the most deficient factor limits plant growth, and increasing the supply of non-limiting factors will not increase plant growth. Only by increasing most deficient nutrient will the plant growth increase. There is also an optimum combination/ratio of nutrients, and increasing them, individually or in various combinations can lead to toxicities and be as limiting as deficiencies.

When individual nutrients are available in excess, it not only unnecessarily contributes to the total volume of solutes in the soil solution, which makes it more difficult for the plant to absorb water and nutrients, it can also create an antagonistic deficiency of other nutrients as toxicity levels block a plant's ability to take them up. E.g., too much Fe (iron) can cause a Mn (manganese) deficiency, with the converse also true, Too much Ca (calcium) can cause a Mg (magnesium) deficiency. Too much P (phosphorous) can cause an insoluble precipitate with Fe and make Fe unavailable. It also interferes with the uptake of several other micro-nutrients. You can see why it is advantageous to supply nutrients in as close to the same ratio in which plants use them and at levels not so high that they interfere with water uptake. I know I'm repeating myself here, but this is an important point.

What about the high-P "Bloom Booster" fertilizers you might ask? To induce more prolific flowering, a reduced N supply will have more and better effect than the high P bloom formulas. When N is reduced, it slows vegetative growth without reducing photosynthesis. Since vegetative growth is limited by a lack of N, and the photosynthetic machinery continues to turn out food, it leaves an expendable surplus for the plant to spend on flowers and fruit. Plants use about 6 times more N than P, so fertilizers that supply more P than N are wasteful and more likely to inhibit blooms (remember that too much P inhibits uptake of Fe and many micro-nutrients - it raises pH unnecessarily as well, which could also be problematic). Popular "bloom-booster" fertilizers like 10-52-10 actually supply about 32x more P than your plant could ever use (in relationship to how much N it uses) and has the potential to wreak all kinds of havoc with your plants.

In a recent conversation with the CEO of Dyna-Gro, he confirmed my long held belief that circumstances would have to be very highly unusual for it to be ever beneficial to use a fertilizer in containers that supplies as much or more P than either N or K. This means that even commonly found 1:1:1 ratios like 20-20-20 or 14-14-14 supply more P than is necessary for best results.

The fact that different species of plants grow in different types of soil where they are naturally found, does not mean that one needs more of a certain nutrient than the other. It just means that the plants have developed strategies to adapt to certain conditions, like excesses and deficiencies of particular nutrients.

Plants that "love" acid soils, e.g., have simply developed strategies to cope with those soils. Their calcium needs are still the same as any other plant and no different from the nutrient requirements of plants that thrive in alkaline soils. The problem for acid-loving plants is that they are unable to adequately limit their calcium uptake, and will absorb too much of it when available, resulting in cellular pH-values that are too high. Some acid-loving plants also have difficulties absorbing Fe, Mn, Cu, or Zn, which is more tightly held in alkaline soils, another reason why they thrive in low pH (acid) soils.

So, If you select a fertilizer that is close in ratio to the concentration of major elements in plant tissues, you are going to be in good shape. Whether the fertilizer is furnished in chemical or organic form matters not a whit to the plant. Ions are ions, but there is one major consideration. Chemical fertilizers are available for immediate uptake while organic fertilizers must be acted on by passing through the gut of micro-organisms to break them down into usable elemental form. Since microorganism populations are affected by cultural conditions like moisture/air levels in the soil, soil pH, fertility levels, temperature, etc., they tend to follow a boom/bust cycle that has an impact on the reliability and timing of delivery of nutrients supplied in organic form, in container culture. Nutrients locked in hydrocarbon chains cannot be relied upon to be available when the plant needs them. This is a particular issue with the immobile nutrients that must be present in the nutrient stream at all times for the plant to grow normally.

What is my approach? I have been very happy with Foliage-Pro 9-3-6 liquid fertilizer. It has all the essential elements in a favorable ratio, and even includes Ca and Mg, which is unusual in soluble fertilizers. Miracle-Gro granular all-purpose fertilizer in 24-8-16 or liquid 12-4-8 are both close seconds and completely soluble, though they do lack Ca and Mg, which you can supply by incorporating lime or by including gypsum and Epsom salts in your fertilizer supplementation program. Ask if you need clarification on this point.

I often incorporate a granular micro-nutrient supplement in my soils when I make them (Micromax) or use a soluble micro-nutrient blend (STEM). I would encourage you to make sure your plants are getting all the micro-nutrients. More readily available than the supplements I use is Earth Juice's 'Microblast'.

When plants are growing robustly, I try to fertilize my plants weakly (pun intended) with a half recommended dose of the concentrate at half the suggested intervals. When plants are growing slowly, I still fertilize often, but with considerably reduced doses. It is important to realize your soil must drain freely and you must water so a fair amount of water drains from your container each time you water to fertilize this way. Last year, my display containers performed better than they ever have in years past & they were still all looking amazingly attractive at the beginning of Oct when I finally decided to dismantle them because of imminent cold weather. I attribute results primarily to a good soil and a healthy nutrient supplementation program.

What would I recommend to someone who asked what to use as an all-purpose fertilizer for nearly all their container plantings? If you can find it, a 3:1:2 ratio soluble liquid fertilizer (24-8-16, 12-4-8, 9-3-6 are all 3:1:2 ratio fertilizers) that contains all the minor elements would great.

How plants use nutrients - the chart I promised:

I gave Nitrogen, because it is the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.

N 100

P 13-19 (16) 1/6

K 45-80 (62) 3/5

S 6-9 (8) 1/12

Mg 5-15 (10) 1/10

Ca 5-15 (10) 1/10

Fe 0.7

Mn 0.4

B(oron) 0.2

Zn 0.06

Cu 0.03

Cl 0.03

M(olybden) 0.003

To read the chart: P - plants use 13-19 parts of P or an average of about 16 parts for every 100 parts of N, or 6 times more N than P. Plants use about 45-80 parts of K or an average of about 62 parts for every 100 parts of N, or about 3/5 as much K as N, and so on.

If you're still with me - thanks for reading. It makes me feel like the effort was worth it. Let me know what you think - please.

Here is a link to the previous posting of A Fertilizer Program for Containerized Plants, in case you'd like to review some of the exchanges.

Another thread that has proven very helpful to a goodly number of forum participants can be found by following this link to information about How Water Behaves in Container Media. You'll find it a fairly detailed discussion about container soils.

Take care. Good luck and good growing!

Featured Answer

tropicofcancer (6b SW-PA)

3 years ago

Stephanie, being on notification for all these posts, it is me again. Advantage of CRF is obvious, it provides a steady supply of nutrients. The release rate is temperature dependent which is nice feature when it is colder when you need little fertilizer. Downside is when it is really hot and in direct Sun. the soil will heat up as well. And beyond say 85-90F soil temperature the roots are stressed and can do without the fertilizer. But CRF being temp dependent will dump out more instead of less. So potentially CRF can stress the plant under hot soil temp conditions.

I do add CRF but I add only half the recommended amount. Why? To cover for situations when I am lazy or too busy. So it acts as a backup. And I control the amount of liquid fertilizer accordingly. CRF also have lifetime eg 3 months, 6 months and even 9 month version is available. So keep that in mind. When it is time to refresh, you can sprinkle on the top and scratch that in with a chopstick or something similar.

Use the humus tea instead of the solid stuff. The solid stuff eventually accumulate and start making it retain more water. In bonsai world organic fertilizers are often stuffed into tea bags and closed. The tea bags are then placed on top of the soil. This way the organic matter does not end in the soil and clog up the pores. It is important factor since you go through all this trouble to make an open structured mix only to clog it up with compost or other organic matter.

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Comments (333)

westes Zone 9b California SF Bay
6 years ago
Just a quick FoliagePro 9-3-6 dosing question: several threads on Gardenweb suggest a dose of 1 tsp per gallon. The FoliagePro instruction label suggests 1/4 of one tsp per gallon, and include in every watering.

I would be watering plants once or twice a week, and the plan is to use FoliagePro once a week. There would be a few exceptions, such as a Lion's Tail plant that is in the gritty mix and seems to insist on water every single day or it starts to wilt. So that one plant would be getting six waterings without fertilizer and one with. Before using FoliagePro, I would flush the container with plain water, just to clean the soil in preparation for new fertilizer.

Given my use, can I get by on the 1/4 of a tsp once per week?
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tapla (mid-Michigan, USDA z5b-6a)
Original Author
6 years ago
1/4 oz/gallon is their maintenance dose, and is designed so you fertilize at every watering. Though that approach isn't something carved in stone, it is effective; still, it requires that you flush the soil when you water, or you risk high EC/TDS levels and skewed nutrient ratios in the soil solution. Because I water by hand indoors during the winter, I fertilize with each watering. In summer, I have too many plants to water by hand every day, so I try to fertilize every weekend when temps allow. I typically use 4 tsp (I overflow a tablespoon measuring spoon by what I'd guess is a teaspoon) in a 2.5 gallon watering can, but withhold fertilizer when I think the mean temp is above 80-85*. If you're growing outdoors, I think you'll find that the maintenance dosage is going to be light.

Al
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Hey Josh, I have been been using Pro-Tekt with my Foliage Pro all winter and i can say that my plants have definately been happier than in the past... When i take my rain water and place it in my watering cans, i add the Pro Tekt first to all of the water and then stir it in. (1/4 tsp per gallon) Then i go back and add my Foliage Pro to the water. I keep it upstairs and let it warm to room temperature and then water. The combination of the two will definately help your plants and im so happy to have found my Pro Tekt. My Hydroponics dealer had to order it for me. I still can't find or he wont (says he cant..) order it for me. He looked it up and says its not available. Hmm? I still order my Foliage Pro from Ebay. They have free shipping anyway. Have fun with your Pro Tekt!!! Hope you are feeling better!!! Happy Spring AL!!! Take Care, Laura
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"It looks like you switched to the Dyna grow 9-3-6 last year. Do you still use CRF in your soil mix if you are still using this fert?" Actually, I rarely use the CRFs at all. I like the near complete control the soluble fertilizers give me in containers. I'm pretty diligent about fertilizer applications, so I really don't need the CRFs to cover the 'in case I forget' base, or for any minor elements they might supply. I included them in the soil recipes to make it easier for others. As long as you're faithful to your nutrient supplementation program, you can easily do w.o them. If you think you'll be lax at times, I'd include them. 109 ppm alkalinity is nothing to be overly concerned about with fast container soils. It would be interesting to learn how the Ca and Mg levels are though. Alkalinity is related to pH because alkalinity (practically speaking and for our applications) determines your water's resistance to pH changes. If you have water 'A' at a pH of 9.0 with an alkalinity of 75 mg/L CaCO3, and water 'B', with a pH of 8.0 (a full point lower to begin with) and alkalinity of 300 mg/L CaCO3, it will take about 4 times as much 35% H2SO4 (sulfuric acid) to bring the water with the lower pH down to That aside - your water is better than mine, so I really doubt you'll have Fe/Mn issues if you're using either the 9-3-6 or MG. I will say though, that bark/peat soils have a potentially high Fe:Mn ratio, so applying Fe w/o Mn could easily create a deficiency of Mn. If I were in your shoes, I would do nothing until I actually saw evidence of an Fe deficiency. Then, I would acidify. Oh - the other likely cause of an Fe deficiency is too much P, which combines with the Fe to form an insoluble precipitate, so avoid the high P fertilizers - they are useless unless you are using them to supply the exact amount of P needed while intentionally (severely) limiting N. I used this strategy last year: I fertilized with regular dosages of 9-3-6 until the plants were well established. I then cut way back on the dosage and added ProTeKt to the solution. I rather like to envision that I used the added K (and got the benefit of the added silicon) to change the fertilizer ratio to 3:1:3 from a 3:1:2. This allowed me to reduce the dosage of N (reducing vegetative growth) while still having adequate P and K. Take care. Al
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You'll find some very, very helpful information in these two threads from the container forum: Container Soils - Water Movement and Retention XVIII Fertilizering Containerized Plants IV Although they discuss containerized plants in general (rather than just fruits), most if not all of the information is applicable to growing fruits in pots. As to some of your specific questions... "My question is once they start growing big are the nutrients in the pot soil is sufficient for the plants?" No. Given the tight confines of pots and the limited soil volume, microbe activity, etc. you absolutely need to provide supplemental fertilization. In my experience, you'll get more reliable results with a synthetic fertilizer, but that's another discussion entirely. "I can change the soil, but am I not going to disturb the roots?" Disturbing the roots isn't necessarily a bad thing. In fact, as you'll see in the linked threads above, periodically disturbing the roots (root pruning, etc.) will enhance the vitality of your plants.
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First, you're correct in thinking that half as much 20-20-20 will yield a solution the same as 10-10-10 (if it was soluble). Another way of saying it is, 1 tsp of 20-20-20 in a gallon of water yields a solution of the same strength as 2 tsp of 10-10-10 in a gallon of water. Generally though, 10-10-10 formulations are slow release, which is different from controlled release, and 20-20-20 formulas are usually soluble in water. While you wouldn't normally mix 10-10-10 in water, it does contain half the N, P, and K that 20-20-20 contains. A lot of growers are quick to recommend a fertilizer with a specific NPK %, but most are unable to tell you precisely why they recommend it. Often, they will offer the idea that fertilizers with a higher first number (nitrogen) are too high in nitrogen to be suitable for houseplants; but they overlook the fact that the amount of nitrogen supplied has nothing to do with the fertilizer ratio, and everything to do with how much N is supplied by the grower. It's as easy to oversupply nitrogen with 10-10-10 as it is with 24-8-16. Actually though, the consequences of oversupplying nitrogen when using 1:1:1 ratio fertilizers like 10-10-10 or 20-20-20 are considerably more severe because you can't even supply an ADEQUATE measure of nitrogen (using 1:1:1 ratios) with out oversupplying both phosphorous and potassium. The perfect fertilizer program would find the grower providing all the nutrients essential to normal growth in the exact ratio at which the plant uses the nutrients, and at a concentration neither so dilute that deficiencies are limiting nor so concentrated that toxicity or antagonistic deficiencies are limiting. It's actually impossible to come even close to achieving that end when using a 1:1:1 ratio fertilizer, or fertilizers actually providing more than 1/6 as much P as N. After the factoring is done for the fact that P and K are actually reported as P2O5 and K2O in a fertilizers NPK %s, you'll find that fertilizers with 3:1:2 ratios (24-8-16, 12-4-8, 9-3-6 are examples of 3:1:2 ratio fertilizers) supply nutrients in almost exactly the same ratio as the average at which plants use therm. There is a significant variance in the overall volume of nutrients taken up by plants, but only a small variance in the ratio the plants actually use. I grow hundreds of species of plants, indoors and outdoors. I formerly used Miracle-Gro 24-8-16 or 12-4-8, to which I added other nutrients. I now use Foliage-Pro 9-3-6 for every plant I grow. It contains all the essential nutrients in a very favorable ratio. It also gets none of its N from urea, which helps to minimize the impact of low light and helps keep houseplants compact. I know that all sounds complicated to a beginner, but if you have questions, don't be afraid to voice them. Al This post was edited by tapla on Tue, Sep 24, 13 at 9:08
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ewwmayo
6 years ago
last modified: 6 years ago
I've followed the Foliage Pro recommended dose rate and my own dilution amounts for many years with regular full watering. EC/TDS levels ended up being quite stable for own gritty mixes. I don't take this measurement very often anymore and concluded the rate recommendation was actually quite good (pretty close to my target values).
westes Zone 9b California SF Bay
6 years ago
@tapla Out of curiosity, are you using a larger watering cart that holds four or more gallons and walking around with that, or are you actually refilling a smaller 2 or 3-gallon hand-watering container?
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mblan13
6 years ago
Westes, I don't think watering once or twice a week in 9b is enough with 5-1-1. Perhaps Al could weigh in on that, but in my experience, this would be problematic.
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four (9B near 9A)
6 years ago
mblan, you are right.
Every hot day.
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westes Zone 9b California SF Bay
6 years ago
@ewwmayo are you using an electrical conductivity meter like this one? How are you collecting the liquid to make that measurement?
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westes Zone 9b California SF Bay
6 years ago
@mblan13 are we talking succulents or citrus trees? For many succulents, once a week seems to be sufficient.

I have a Leonotis Leonurus (lion's tail) that was just planted in the gritty mix and it seems to want water more than once a day or it immediately wilts. So there is a lot of variation here.
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ewwmayo
6 years ago
Westes - Yes, I am with the pour-thru method. It's reasonably accurate.
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westes Zone 9b California SF Bay
6 years ago
@ewwmayo are you saying that you collect water coming out of the container and using the meter against that? What is your target for a healthy EC number?
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ewwmayo
6 years ago
Westes - It's the pour-thru method by Cornell University. See here http://www.css.cornell.edu/courses/260/Media%20testing.pdf

My target for fertigation water was 500 µS/cm, every other or every third watering. I think what's "healthy" is a very hard question to answer definitively.
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mblan13
6 years ago
I don't grow succulents, so I'll defer to those that have experience with them.

I'm referring to Leonotis and most fast growing annuals and perennials. I grow Cuphea, Salvia, Porterweed, Hamelia and Lantana. The Salvia and Loenotis definately needed watered every day, the others, every other day.
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Conrad Todd
5 years ago
I got the product finely and heres what it looks like..... suppose to be mini nuggets looks like multch to me...
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Conrad Todd
5 years ago
Can anybody recommend where to get the right size bark around Montana because so far I have been skunked.....
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edweather USDA 9a, HZ 9, Sunset 28
5 years ago
Around Montana? That's a bit of a large area :-/. The name of the nearest large town might help, if someone wanted to search online. Mini nuggets, not hardly. Mulch is correct, but not really usable for the mix.
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Conrad Todd
5 years ago
Yah around Missoula which is northwestern montana... the only place I could find that sells bark is the moutainwestbark who sold me this crap....
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stephaniedan
3 years ago
last modified: 3 years ago
Thank you Al for the informative post! I was wondering if there are any advantages / disadvantages to using CRF over liquid fertilizer. I currently have both and am a bit lost.

Also, I made the 5-1-1 soil to be used very soon but I have a huge bag of red worm hummus and don't know what to do with it. My plants are in containers as I don't have a garden. Should I make hummus tea or something out of it or donate it to someone who might have better use of it?
tapla (mid-Michigan, USDA z5b-6a) thanked stephaniedan
stephaniedan
3 years ago
Thank you I really appreciate this wealth of information. I hope im not overcomplicating by posting in multiple threads at once.

This explanation makes a lot of sense and helps a lot!

So correct me if wrong - essentially when you half the dose of CRF you will also use liquid fertiliser diluted to half strength to water the plants with.
Then in hot days you don't add liquid fertiliser.

Would the quantity of use of organic / hummus tea be irrelevant to the amount of chemical fertiliser used? Or do i need to be wary of over-fertilising ?
tapla (mid-Michigan, USDA z5b-6a) thanked stephaniedan
tropicofcancer (6b SW-PA)
3 years ago
To keep it simple, yes I add half strength liquid fertilizer when full strength is required. But when the plant is growing vigorously I would bump up the liquid up to twice the strength.

But to be exact is not that straightforward. You have to know the NPK of each of the fertilizer and recommended strength into consideration. On top of that you have to know the release profiles of the CRF. So I have boiled it down to simple rules. During hot periods stop the liquid fertilizer, and during rapid growths boost the dosage. Near the end of the season wind it down to 1/4 strength - but by then the CRF would have been consumed too. During winter use 1/4 strength every two weeks or so. But you have to adapt a bit to your environment too. You probably do not have winters like us and you may still have good bit of growing period compared to us.

In US Osmocote 19-6-12 6 months release is popular. Ideal time to apply that would be say April/May and that will take you to Sept/Oct. You can apply earlier during cooler period and it should not harm since below 50F they do not release much. I use a different one that is a 3 month formula and space out the application accordingly.

May be Al has a better formula.

I think humus tea is safe all year round and it should not cause any problems. It has very low NPK and should not be a problem. I am guessing it will add some beneficial microbes too. I limit my organics usage to in-ground growing.
tapla (mid-Michigan, USDA z5b-6a) thanked tropicofcancer (6b SW-PA)
tropicofcancer (6b SW-PA)
3 years ago
stephanie: Thank you I really appreciate this wealth of information. I hope im not overcomplicating by posting in multiple threads at once.

Thanks, and it is great that you find all this info useful. And no worries using multiple threads. That is how it generally happens around here. And it so happens I am around and saw the notifications. I learn too from the questions and it also help me figuring out how best to explain without getting caught up in complex issues.
tapla (mid-Michigan, USDA z5b-6a) thanked tropicofcancer (6b SW-PA)
RoseMe SD
3 years ago
@tapla (mid-Michigan, USDA z5b-6a) hi Al, Thank you for this helpful read before I transplant my new M. Figo to another pot. Regarding fertilizer in pot (or in my case, root pouch), can kelp liquid supplement be added to a balanced fertilizer you recommended, both given regularly as part of watering protocol? Will using both increase risk of burning roots through additive or synergistic effect? Again my root pouch drains water in all walls so I can't e sure that I am doing the " flushing 20% out" protocol when watering.
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four (9B near 9A)
3 years ago
last modified: 3 years ago
Please pardon the ignorance. When ratios are expressed as 9-3-1, 24-8-16, 12-4-8, instead of 3-1-2, are the products respectively three, eight, four times stronger (more concentrated) ?
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litterbuggy (z7b, Utah)
3 years ago
last modified: 3 years ago
Hi, y'all. Let me know if my post belongs somewhere else or if the question has already been answered. I tried searching but didn't find anything.

My fertilizer question is whether adding Dyna-Gro Pro-Tekt to the Foliage-Pro I've used for years. Pro-Tekt is 3-% soluble potash and 7.8% silicon, and is supposed "reduce stress due to heat, cold & drought," will help my struggling porch plants.

My ficus benjamina and schefflera spend their summers on my WSW facing porch that have thrived for about 3 years in Al's 5-1-1. They're due for repotting and root pruning, and I'd love to prune the tree to get a fuller shape, but I've held off because they're struggling mightily to survive against this year's unusually prolonged high heat and heavy smoke, to the point that they're losing leaves and barely back-bud when I pinch-prune (I forget Al's term for it). At this point they need watering at least once a day, and even that is marginal when it's 105 degrees with <15% humidity and enough of a breeze to dry the medium out in several hours. Not repotting was probably a mistake, but I think I'm kind of stuck with it at this point.

Does anyone have experience with or a general opinion about Pro-Tekt or similar supplements? I expect the heat to last until late September, and I'd like to at least see the trees build some reserves before they come indoors, where they only get mediocre light even in summer.

Any other advice is welcome, of course!

Thanks!!
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tapla (mid-Michigan, USDA z5b-6a)
Original Author
3 years ago
Replies below to Rose, Four, and Litterbuggy

Rose said: Regarding fertilizer in pot (or in my case, root pouch), can kelp liquid supplement be added to a balanced fertilizer you recommended, both given regularly as part of watering protocol? You can mix the 2 nutrient solutions, but the seaweed supplement will be superfluous and probably counterproductive if you're using Foliage-Pro 9-3-6. The reason: FP 9-3-6 has ALL nutrients essential to normal growth, in a ratio that closely matches the ratio at which the average plant actually uses the nutrients. The seaweed emulsion does not have all essential nutrients, and using it will change the ratio at which nutrients are represented in the soil solution. There is no potential benefit to be had by adding a product that duplicates some nutrients but not others. Always remember that an excess of any nutrients has the same potential to limit as a deficiency. Will using both increase risk of burning roots through additive or synergistic effect? Not through synergism, though if it was to elevate the EC/TDS (electrical conductivity/ total dissolved solids - a measure of the level of salts in the soil solution) I would expect it to be negligible. Again, the issue lies more in the fact that you don't need a product that alters the nutrient ratio when you're using a product with a ratio that so closely matches the ratio at which the plant takes up nutrients. Again my root pouch drains water in all walls so I can't e sure that I am doing the " flushing 20% out" protocol when watering. I remember addressing this for you on another thread; but, if you still have a question just bring it up again.

****************************************************************************************

Four says: When ratios are expressed as 9-3-1, 24-8-16, 12-4-8, instead of 3-1-2, are the products respectively three, eight, four times stronger (more concentrated)? A fertilizer's RATIO is something akin to finding a group of fraction's lowest common denominator. A fertilizer's NPK %s should be written with a dash between the numbers which represent the % of the product by weight. Ratios, on the other hand, are a more useful way of establishing a fertilizers suitability. Ratios are written with a colon between the numbers. Example: 24-8-16, 12-4-8, and 9-3-6 are all 3:1:2 ratio fertilizers. 30-10-10 is a 3:1:1 ratio, and 10-15-10 is a 2:3:2 ratio.

If you were to compare/ analyze the instructions on packages of 24-8-16 and 12-4-8, both commonly used fertilizers, you would find the packager providing instructions that would have you making a solution of the same strength regardless of which product you used, but you would need to use twice as much 12-4-8 as you would 24-8-16. The same relationship exists in 1:1:1 ratio fertilizers like 7-7-7 and 14-14-14. End result would yield the same solution strength, but it would require you adding twice as much 7-7-7 as 14-14-14.

*****************************************************************************************

Litterbuggy says: My fertilizer question is whether adding Dyna-Gro Pro-Tekt to the Foliage-Pro I've used for years. Pro-Tekt is 3-% soluble potash and 7.8% silicon, and is supposed "reduce stress due to heat, cold & drought," will help my struggling porch plants. The silicon in PtoTeKt 0-0-3 is like Ca(lcium) in that it must be in the nutrient stream at all times if newly forming cells are to benefit. It helps the plant better deal with extremes of temperature, moisture levels, with insect herbivory, and attack by biotic pathogens. It's not a cure-all, however. If the plant suffers from tight roots, poor light, low fertility, nutritional deficiencies/ imbalances/ toxicities, it won't fix or alleviate associated stress factors.

If you want more info on opalene silicon for plants, send me a message and I'll figure out how to get it to you.

Al
RoseMe SD
3 years ago
last modified: 3 years ago
I believe the "selling point" of kelp food is not the big 3s, but algae enzymes used for growth regulators/hormones (auxins, cytokinins, gibberellins). They were described as plant "vitamins" to me.
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four (9B near 9A)
3 years ago
last modified: 3 years ago
1) Is it valid to compare stated percentages of individual nutrients in a granular product to those in a liquid product? E.g. 6% Ca in Micromax, 2% in Foliage-Pro.

2) Some of Micromax' ingredients are commented "water soluble", others not.

Do the nonsolubles become available much later? Does their availability require microbial work?
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tapla (mid-Michigan, USDA z5b-6a)
Original Author
3 years ago
last modified: 3 years ago
While meandering down any fertilizer aisle you'll be mobbed with marketing campaigns so embellished with outlandish claims as to not be outdone by any other commodity I can think of. Plants synthesize their own vitamins and the chemicals you mentioned (auxins, cytokinins, gibberellins), and fertilizers cannot cannot make plants grow better than they are capable of growing, they can only help restore normal growth. That auxin/ cytokinin/ gibberellin can be isolated from seaweed shouldn't lead to the conclusion that applying seaweed emulsion benefits other plants which already enjoy top-notch nutritional supplementation.

There is some research that indicates seaweed emulsions can briefly help to stimulate rooting in cuttings and transplants, but the effect is very short-lived as the emulsion is rapidly mineralized by soil biota.

******************************************************************************

1) Is it valid to compare stated percentages of individual nutrients in a granular product to those in a liquid product? E.g. 6% Ca in Micromax, 2% in Foliage-Pro. .... not sure what you mean?

2) Some of Micromax' ingredients are commented "water soluble", others not.

Do the nonsolubles become available much later? Yes Does their availability require microbial work? Organic compounds and insoluble chemicals must go through the process of mineralization (by soil biota) before the nutrients become available in a form (salt) that allows the nutrients to pass through cells' semi-permeable membrane.

Al
four (9B near 9A)
3 years ago
Thanks, Al.

Please help me to reconcile the seemingly incompatible statements about salt(s):

> "form (salt) that allows the nutrients to pass through cells' semi-permeable membrane"

> "as salts accumulate, both water and nutrient uptake is made more difficult"
RoseMe SD
3 years ago
I wonder also if 0-20-20 blend is required or recommended to fertilize with during the fall? They consider this special recipe to be a "winterizing fertilizer".
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gardengal48 (PNW Z8/9)
3 years ago
"I wonder also if 0-20-20 blend is required or recommended to fertilize with during the fall? They consider this special recipe to be a "winterizing fertilizer".

Only if you are fertilizing a lawn:-) It is not a suitable fert for any containerized plants!
Meyermike(Zone 6a Ma.)
3 years ago
last modified: 3 years ago
Is it necessary for a fertilizer to contain calcium like say for citrus trees?

There are are some that say they contain calcium , especially tomato ones and others that do not have calcium any at all ,like Miracle Grow.

I am happy that the Foliage Pro has the perfect blend, but I don always have access to it.
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tapla (mid-Michigan, USDA z5b-6a)
Original Author
3 years ago
last modified: 3 years ago
Four said: Please help me to reconcile the seemingly incompatible statements about salt(s):

> "form (salt) that allows the nutrients to pass through cells' semi-permeable membrane"

> "as salts accumulate, both water and nutrient uptake is made more difficult" I'm at a disadvantage because the context in which the first phrase appeared is missing, but maybe this explanation will help: I'll start with diffusion and move to osmosis. Molecules of liquids/ gasses move/ diffuse from an area of higher concentration to one of lower concentration simply as a result of probabilities. Molecules of gas/liquid will be in motion constantly and randomly, colliding with each other and dissimilar surrounding molecules. If you have 2 compartments such that compartment 1 has many molecules of a given substance (gas or liquid), and compartment 2 has no molecules of given substance and the compartments are connected by a tube, there can initially be no movement of the molecules from 2 to 1 because there are none in 2. As soon as the diffusion begins and some molecules move from 1 to 2, molecules of the substance will begin to move randomly back and forth between 1 & 2. Probability dictates that more molecules will move from 1 to to until a state of equilibrium is reached and an equal number of molecules will be moving back and forth until something changes the balance.

Let's move to osmosis now and retain the molecular theme while you imagine a container separated into 2 compartments by a semi-permeable membrane. If both compartments contain water, the water molecules will move back and forth at the same rate; however, adding a solute to one side affects (decreases) the likelihood of water molecules moving out of that side into the other. There are only theories as to why that occurs, but the key element to understand is the more solutes a solution contains, the less likely it is that the water in that solution will move through a semipermeable membrane into the adjacent compartment, so the net flow of water is from regions of lower solute concentration to regions of higher solute concentration.

For more info, use searchwords hypertonic, hypotonic osmosis tonicity.

************************************************************************************

Rose said: I wonder also if 0-20-20 blend is required or recommended to fertilize with during the fall? Many use no nitrogen fertilizers, which are often touted as the nutritional ticket to prepare your plants for winter's ravages and prevent them from producing tender fall growth that will be killed by the first freeze. Unfortunately, there is no credible evidence that this is true. Let's think about this. When do plants set next grow season's buds? Summer. What part does nitrogen play in determining onset of bud-break? None. Day length (actually it's the length of the dark period) and temperature are the factors that force initiation of bud-break.

It's also frequently said the excessive amounts of P (relative to the % of K) in 0:1:1 ratio fertilizers like 0-10-10 or 0-20-20 improve additional resistance to winter chill injury, but there is no credible evidence to support that, either.

The conventional wisdom also says fertilizing with high levels of phosphorus in the fall will prepare the plant for winter by increasing its cold hardiness. There is no credible evidence to support this contention. The beginning of a plant's advancement toward dormancy has begun by budset. Movement of water containing increasing levels of solutes moves through the xylem to above ground organs where the solutes serve as an anti-freeze that allows water in cells to resist freezing at temperatures well below the freezing mark, and you'll find plenty of anecdotal evidence but no scientific evidence that over-fertilizing with P and/or K is a strategy to be preferred over fertilizing with a complete fertilizer with a favorable NPK ratio.

Too, your plants will thank you with a more enthusiastic spring push should you decide to include N in your fall fertilization regimen for as long as medium temperatures are above 55*. Plant's store nitrogen, and nitrogen is hard to come by in spring when soils are cold, so it's good to have something in reserve for those chilly days.

Al
tapla (mid-Michigan, USDA z5b-6a)
Original Author
3 years ago
Is it necessary for a fertilizer to contain calcium like say for citrus trees? Not in all cases. E.g., if the composition of the medium allows you to use a liming agent (that is to say, if it doesn't have a large fraction of coir or CHCs, the pH of which precludes the use of a liming agent) it isn't essential that the fertilizer being used has Ca or Mg.

There are are some fertilizers that say they contain calcium, especially those for tomatoes, and others that do not have any calcium at all, like Miracle Grow. Yes, buyer beware! Understanding your plants' needs and how to ensure they are met is essentially our only job when it comes to growing things in containers.

I am happy that the Foliage Pro has the perfect blend, but I don't always have access to it. I would think it's just a click away, so long as you maintain access to the internet.

Al
four (9B near 9A)
3 years ago
Thanks.

>"the more solutes a solution contains, the less likely it is that the water in that solution will move through a semipermeable membrane" ___ So, fertilizer solution itself works against the cells' intake of fertilizer solution. And we would minimize the difficulty by using always very low concentration. (provided that the plant is ok with the extra water of correspondingly more frequent applications)
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chamaegardener (Z5) Northeast Illinois
2 years ago
On the issue of watering with 20% flow-through to avoid build up of solutes in soil, if I am only fertilizing every 2 to 3 waterings, will the waterings without fertilizer flush the soil sufficient so that on the fertilizing days I don't have to waste 20%?
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Meyermike(Zone 6a Ma.)
2 years ago
Well. Thank you I use the 5.1.1 mix so I don’t have to worry about the salt issues with fertilizing )
Thanks Al for the seeds !
seasiderooftop
2 years ago
Thank you to @tapla (mid-Michigan, USDA z5b-6a) for this thread, I am just discovering it now and am very grateful for all this information.

I have a question about enzymes. Is it true that adding an enzyme solution as well as a trace minerals solution (co-enzymes) will help container plants use the nutrients in organic fertilizer?

Please note, I am not asking if this is a preferable route, since obviously using synthetic fertilizer is an easier one-step feeding routine, and gets the job done.

I would just like to know if enzyme solutions, especially used in combination with co-enzyme trace mineral solutions, really work or not to make the nutrients in organics available, or if it's a myth to sell more stuff.

I have some pelletized composted sheep manure and have been scratching that into the top of the potting mix before adding my summer mulch of pumice. I have been using enzyme solution (Plagron PureZym) along with a trace minerals solution (Canna Trace), in the hopes of helping break down the composted manure. Am I wasting my time/money with all of this?
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four (9B near 9A)
2 years ago
A guess about "mulch of pumice" : that it reflects heat onto undersides of leaves.
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Meyermike(Zone 6a Ma.)
2 years ago
last modified: 2 years ago
The biological world that needs to happen in such a perfect manner and consistently is makes no use to use any organic fertilizer in containerized plants.
You’d be surprise at how much money is made on that and how much money people spend.
There is a lot more to it than what I said but I have spent hundreds of dollars with no good results I wish I had saved before I ever discovered this particular forum.
Not a one person I know very successful with perfect growing container plants uses organic fertilizers anymore except for in ground.
One good fertilizer that gives your plants everything they need is all that is needed.
Then of course growing conditions plays a huge part too
Mike
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Michele Rossi
last year
Dear @tapla (mid-Michigan, USDA z5b-6a), would you be so kind as to write something again on the subject of high temperatures and fertilizer? I couldn't find the directions you've given in the past. These are the current temperatures and not whether to fertilize.
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four (9B near 9A)
last year
It is the soil temperature that matters more. At a given warm ambient temperature, soil in shaded containers will have lower temperature than soil in sunned containers. My recollection is that tapla wrote that we would not fertilize above 80 degrees F. soil.
Michele Rossi
last year
last modified: last year
It is the soil temperature that matters more. At a given warm ambient temperature, soil in shaded containers will have lower temperature than soil in sunned containers. My recollection is that tapla wrote that we would not fertilize above 80 degrees F. soil.

I had forgotten this thing and now I am remembering. But how do you determine the soil temperature? And in this regard: should we try to avoid placing the pots in the sun? Do I mean shield them with something? Because I think for example ficus benjamin are fine in the sun, right? Should their pot instead ideally be in the shade?
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four (9B near 9A)
last year
Thermometer. Or just assume that effective shielding or shading will be adequate.

Often it possible to find places in which pots can be shaded by something that does not also shade their plants. Sometimes I bury potted plants (taking drainage into account).
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Michele Rossi
last year
Sometimes I bury potted plants (taking drainage into account).

What do you mean?
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four (9B near 9A)
last year
Loveplants2 8b Virginia Beach, Virginia
last year
Aka plunging …
tapla (mid-Michigan, USDA z5b-6a) thanked Loveplants2 8b Virginia Beach, Virginia
Meyermike(Zone 6a Ma.)
last year
Laura
Hope all is well. 😊
tapla (mid-Michigan, USDA z5b-6a) thanked Meyermike(Zone 6a Ma.)
Loveplants2 8b Virginia Beach, Virginia
last year
last modified: last year
Thank you Mike!! 🌺 Doing great 🙄 Hope you are!! 😊
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Michele Rossi
5 months ago
My recollection is that tapla wrote that we would not fertilize above 80 degrees F. soil.

These are the temperatures of these days:

@tapla (mid-Michigan, USDA z5b-6a), I would like to return to this topic briefly. I have read many things you have written about the fact that one should not fertilize when temperatures are high and why it is good to avoid it. Here however for about 2 months the maximum temperatures are on average 34-36 degrees centigrade and in the 30 days before and in the 30 days after anyway around 30 degrees centigrade. In short, the temperatures here are much higher than in Bay City, Michigan. Avoid fertilizing in the two hottest months? Avoid fertilizing for almost 4 months? In other words I ask you: does it do more harm not to fertilize for such a long time or to fertilize with very high temperatures?
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Fertilizering Containerized Plants IV

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