Fertilizing container tomatoes

5 years ago

Sorry to ask so many questions. I'm confused about how to fertilize my container tomatoes. I've searched on this site and others and there's a wide variety of advice. Will say I'm trying to grow them organically and grew them from seed indoors.

As seedlings I gave them Organic Start! liquid fertilizer according to the directions. When I transplanted them, I threw in a couple of handfulls of Dr. Earth Home Grown Tomato, Vegetable & Herb Fertilizer (4-6-3). That was a month ago. Now what? We have a local organic nursery that I can buy tea from. I could also use the Dr. Earth.

I'm unclear what I should use and how often. My plants have blossoms and I'm in Boise, Idaho in zone 6b if that matters.

The plants are in 30 gallon fabric pots (except one is in a plastic pot). They get lots of sun, this pic was taken in the early morning when the house was shading them.

Thank you for any thoughts!

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gardengal48 (PNW Z8/9)

5 years ago

It is tough to be completely organic while growing in containers. Container culture and the media necessary to grow well in containers negates the presence of the microbiology present in inground soils. And without high populations of naturally occurring soil organisms, there is nothing in the potting media to break down and convert organic ferts into plant usable forms. To be most efficient at fertilizing your plants you need a fully water soluble fert, which most organics are not. Fish and seaweed emulsion are a good place to start and there are a few liquid organics on the market...Dr. Earth makes a couple. But I haven't researched them well enough to know if they offer all the trace elements necessary as well as the macros.

While I am fully organic elsewhere in the garden, I opt for a commercial synthetic liquid fertilizer (Dyna Gro's GROW) for all my containers to make sure they are receiving all the nutrients they require. It is one of the few ferts that offers a full range of all required trace elements.

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Comments (15)

digdirt2
5 years ago
Agree completely with gardengal. Liquid organics is the solution for trying to grow organically in containers. Dry and granulated organic supplements simply cannot provide the nutrients effective because the containers lack the required "middle man", the micro herd. And there are literally 100's of liquid organic supplements available. For example: https://www.planetnatural.com/product-category/organic-gardening/organic-fertilizers/liquid-fertilizer/

It is the frequency of application that becomes the real challenge and as a very general guideline - weekly works for me with those containers that are not set up on continuous low-dose fertigation. I prefer the Earth Juice products but General Organics also makes some good products.

Dave
C. S. thanked digdirt2
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One thing I'd consider is are you(meaning anyone)actually container gardening or raised bed gardening? If that container is set on the ground and can anchor itself with it's roots then it has another(not necessarily an ideal one)source for nutrients. I think without a doubt container(true) gardening in regards to fertilization is quite tricky. This is especially true when you're using liquid fertilizers. They tend to drain on out. Last time I grew tomatoes in a container was quite an adventure. The plants were cuttings(of a cutting of a cutting) I took in August or September and brought in the house and kept alive They wound up in the end living about a year and a half and dying from disease. I had tomatoes in May though. I fed em fish emulsion once a week. I don't remember if I stopped but the stinky stuff used to just run right through them. They were pretty productive. For the tomatoes in my greenhouse in the ground last year though I vegged them out and at some point I just stopped fertilizing. They got slow release(organic), fish emulsion and then nothing. They were monsters and loaded with fruit. Now the trick this year for me is to make sure i can manipulate the fertilizer routine like i did last year and utilize the cozy greenhouse to get them jumping. It's not going to be easy. I think it starts with knowing how much slow release fertilizer(organic) per cu foot if you will along with the tricky maintenance(ph concerns me..how fast does garden lime kick in?, also micro nutrients). 2 things I will make sure of, the containers breathe(greenhouse can go well over 120 degrees, although cool shot with the hose drives the heat out)and use organic so there is no real over feeding.
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2) I grow my tomatoes in 18 gal containers and usually end up fertilizing at full strength every weekend when they have put on some mass & are growing robustly. The increases in either strength or frequency would/should be most closely tied to temperatures, planting mass, and your watering habits, so it's difficult to offer a one-size-fits-all answer to the question. Your plants will tell you if you make it a point to observe them closely. Soon, it will be second nature to 'know' when to fertilize after only a glance or based on experience. You actually want to be able to anticipate your plants needs and fertilize just before they experience the effects of any deficiencies. 3) I'm familiar with the product, and know that it forms insoluble precipitates when mixed with some fertilizers, but I can't tell you which ones. I know that the FP fertilizer when mixed with ProTeKt does form a precipitate, but I'm unsure if the same occurs with the LL. I've never had a need for it. 5) No, by reducing the dosage of your fertilizer you limit N - to prevent a K deficiency, you increase the K supply. You didn't ask about using a different fertilizer - you asked how to make 9-3-6 work. ;o) By all means - use another fertilizer with lower N if you wish. A 2:1:2 ratio is what I would suggest. 6-2-4 is the same fertilizer as 24-8-16, it's just that the amount of 6-4-2 you would be instructed to mix into a given volume of water to reach a recommended dosage would be 4x that of 24-8-16. You can make 6-2-4 by diluting 24-8-16 5:1, water:fertilizer. Al Here is a link that might be useful: This might help more
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In containers or in the ground? Makes a big difference. Container plants normally require dilute feeding on a regular weekly basis anyway regardless of plant type. In ground plants are routinely fed after first fruit set and again 6 weeks later etc. But in that case it all depends on the type of feeding routine you are using (ie: fertigation vs. side dressing), the soil prep done before planting, etc. Dave
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So, basically what you guys are saying is potting soil is sterile and needs help with things like manure or compost. It sounds like next year I have make up my own planting soil mixture for containers then. You can certainly go that route if you wish and you'll find several recipes for container mixes over on the Container Gardening forum here. Since you are using containers rather than in-ground beds, that will be the best forum source for info for you. But none of those recipes will contain dirt (soil). Some compost and composted manure, fine but soil isn't used in containers because it compacts, drains poorly, and the roots rot. Not to mention that is can be a source of damp-off, pests, and disease problems. Experienced container gardeners use only soil-less mixes in containers to avoid those problems. And it isn't that those mixes are necessarily "sterile", they aren't. There are many good container mixes that come with mycorrhize added to them. Pro-Mix is one that is often recommended on several of the forums here. I use it myself. But that still isn't going to solve the problems of nutrient leach. Containers require frequent, regular supplemental nutrients, regardless of what you mix into the container to begin with since the roots are "contained" unlike in a garden and the nutrients wash out when you water unlike in a garden. That, plus maintaining consistent moisture levels, are the biggest drawback to growing in containers. How much of a problem it is all depends on the size of the container you are using and you didn't mention how large your container is. Take a look at Jaybo's pics linked below. He is using 31 gallon self-watering containers. Dave Here is a link that might be useful: Earthtainer Garden Pics
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C. S.
Original Author
5 years ago
Ok. Thanks so much! I really appreciate it!
edweather USDA 9a, HZ 9, Sunset 28
5 years ago
Texas Tomato Food is also a very good organic liquid fertilizer. I feed daily with it, and have had great results this year. If your container media is anywhere near as fast draining as mine, you'll need to feed often. Tomato plants are heavy drinkers and feeders.

http://www.tomatoville.com/showthread.php?t=27229
C. S. thanked edweather USDA 9a, HZ 9, Sunset 28
gorbelly
5 years ago
Texas Tomato Food is not OMRI listed, so you can't technically call it organic.

That said, I generally stick to organic methods in my garden, but I use TTF. I get very good results from it. I'm sure getting hydroponic ingredients in bulk and mixing your own would be cheaper and likely work just as well, but in a garden my size (only room for 10 in-ground tomatoes and a few more in containers) it's just easier to buy a pre-mixed product in smaller quantities.
C. S. thanked gorbelly
edweather USDA 9a, HZ 9, Sunset 28
5 years ago
Ok then. I thought it said organic on the label, but must have misread it. Not that I grow organic anyway....just thought it was. Thanks for the correction.
gorbelly
5 years ago
Their BioActive fertilizer, a dry fert, is organic. But not their liquid formulas.
edweather USDA 9a, HZ 9, Sunset 28
5 years ago
Back on track here, I meant to mention with 30 gal containers and a good fertilizer, those plants will get HUGE.
C. S. thanked edweather USDA 9a, HZ 9, Sunset 28
C. S.
Original Author
5 years ago
And that's ok right?
Barrie, (Central PA, zone 6a)
5 years ago
Not necessarily! Nitrogen is a highly mobile nutrient and fine to feed from top fed liquid but other nutrients, especially Phosphorus, may be hard to place in the root zone when needed. It may be best to either place most of Phosphorus in the potting mix or better yet use slow release fertilizer like Osmocote when potting. I’ve seen results of a flower trial where water soluble season feeding was compared to coated nutrients in the potting mix and results were amazingly in favor of coated pot fertilizer.

Not organic and Not normally cost effective unless you plant in pots.
C. S. thanked Barrie, (Central PA, zone 6a)
fungus
5 years ago
last modified: 5 years ago
Something like tomato tone should work well. Just add regularly once the fruits are starting to grow, like a spoon every two weeks let's say and incorporate into the mix. The problem is at some point the mix is full of roots and it's hard to incorporate. Organic works good in containers but there might be some microelement deficiencies later in the season since the clay base of the soil is not there for mineral content (you could add some rock dust at beginning of season or buy some microelement mixture to add from time to time in tiny amounts).
C. S. thanked fungus
gorbelly
5 years ago
I used Tomato Tone in containers once upon a time. Liquid fertilizer works way better in containers. Much improved yield and plant health.
C. S. thanked gorbelly
gardengal48 (PNW Z8/9)
5 years ago
"Organic works good in containers "

There is NO way dry organics work well in containers!! Unless you are using some weird poorly draining mix that includes a lot of compost or garden soil. Container potting soil lacks the soil biology necessary to process these sorts of ferts and convert them into plant usable forms.

If you think dry or granular organics like TomatoTone works well in containers then you do not understand the basic difference between a water soluble synthetic fert and an insoluble organic product.
edweather USDA 9a, HZ 9, Sunset 28
5 years ago
Yes, frankly, it's best to leave organics for the ground. In containers, any decent liquid or water soluble fertilizer should work well. Texas Tomato, Foliage Pro, and even Miracle Grow if you're on a budget. Doesn't hurt to have a Controlled Release Fertilizer (CRF) in there as a backup. Osmocote was mentioned, and Miracle Gro make a good product called Shake and Feed, which contains calcium and magnesium. And yes, imo big plants are good if managed properly. If I had 30 gallon containers, I'd need 10 foot cages. Your plants will probably overwhelm your cages in short order. Can you possibly attach another cage on top of those?
gardengal48 (PNW Z8/9)
5 years ago
I grow cherries (indeterminate) in 20G containers and it is hard to find tall enough cages that will fit in the containers!! And I lack the patience or creativity to make my own :-) So I just let the plants sort of cascade over the top. It doesn't seem to impede their flowering or fruiting in any way although by the end of the season, some of the upper branching structure is a bit split by the weight of the fruits.

I also dose with Osmocote Plus when potting up and periodically during the season with Dyna Gro GROW. In an area that is notoriously difficult to grow toms well due to cool summer temps, I get amazing crops from the cherries!

Fertilizing container tomatoes

gardengal48 (PNW Z8/9)

Comments (15)

digdirt2

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C. S.
Original Author

edweather USDA 9a, HZ 9, Sunset 28

gorbelly

edweather USDA 9a, HZ 9, Sunset 28

gorbelly

edweather USDA 9a, HZ 9, Sunset 28

C. S.
Original Author

Barrie, (Central PA, zone 6a)

fungus

gorbelly

gardengal48 (PNW Z8/9)

edweather USDA 9a, HZ 9, Sunset 28

gardengal48 (PNW Z8/9)

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