Do a search in the forums there are many threads about container blueberries.

Yes, I've read them all, but I'm asking questions for which I haven't found complete or satisfactory answers...

The soil in the container helps maintain desirable pH. It also keeps the nutrients from being flushed out with each watering. Something like sand will leach out all the nutrients, not just nitrogen. Nitrogen will leach out quickly in any soil and must be replenished often.

I have used Hollytone with ammonium sulfate. I would fertilize with Hollytone once a month and with ammonium sulfate weekly except the week I used Hollytone. You will need something besides ammonium sulfate for the micronutrients. The rate varies with climate for Hollytone, but I used about a handful per month. I now use miracle grow miracid but you do have to be careful with getting too acidic. I used Hollytone for acid loving plants.

As far as the health of the plants, they do not know the difference in organic or synthetic. They all must be broken down to the elemental nutrient to be absorbed. Blueberries do need high levels of organic matter, but you will have that in a potting mix. Keeping a healthy plant is usually easier in a container using synthetic fertilizer because they are usually more readily available than organic. It can take weeks for some organic fertilizer to release nitrogen where synthetic will be almost instantly available.

garybeaumont,

Are you saying that the nitrogen released from ammonium sulfate would easily leach away in a container? I thought the opposite was true.

fruitnut had written in a thread that "the ammonium ion is strongly held in the soil, you won't wash it past the roots":

http://forums.gardenweb.com/discussions/1449649/blueberries-ammonium-sulfate-question

So if I apply a ammonium sulfate based solution and a week later, water heavily the container, whatever nitrogen there is would leach away?

Als, does Miracid have all the nutrients or micronutrients that a blueberry plant needs? Should anything else be added?

So you would suggest Miracid over an organic fertilizer like Hollytone for blueberry containers?

All nitrogen that is in a form available to the plant is easily leached away. Remember, in a container it is getting several feet of water per year. Giving them small consistent supply of nitrogen is the best way to know they are getting enough. You can add 1/2 teaspoon per gallon of ammonium sulfate every week or two. It really depends on how the plants are growing. Growing too fast, decrease the interval of the nitrogen solution. Too little growth, use the 1/2 teaspoon gallon solution more often. Do not use the ammonium sulfate on plants that are dry. It can burn the roots.

Some organic fertilizer has to have bacteria to break down the organic substances to eventually release the nitrogen. However, the bacteria ties up most of the available nitrogen before it releases it later. If the plant is lacking nitrogen, adding organic matter can make the problem worse before making it better.

I think that either Hollytone or Miracid will work. Remember that the nutrients on the 3 major types of nutrients are Nitrogen, phosphate, and potassium. (15-5-10 for instance has 15% Nitrogen, 5% phospate, and 10% potassium.). Most organic fertilizer has lower levels of nitrogen than is needed in container plants.

As long as you are adding the ammonium sulfate in addition to the organic fertilizer, I think it will work. You are really going to have to learn to read your plants to see if they are lacking something.

Blueberries are kind of hard to read because the first leaves almost always look like they are lacking something but green up in a couple to month later. However, they seems to be pretty easy for me to grow in containers. But I am in a totally different climate and grow southern highbush blueberries. That said I did have 2 bushes that died on me this week. Not sure what went wrong but they were in a 3 gallon pots and we had hot temperatures. The rest of mine are doing fine. The bigger they get the more room for error you will have.

When you give an ammonium sulfate based solution to your plants, do you make sure that there it is certain amount of leaching fraction in order to avoid salt build up? Or how do you deal with salt build up?

So if you give it again a week later, then that would mean that any amount of nitrogen made available by bacteria from the previous application would leach away (if there is a leaching fraction)?

I get 55 inches of rainfall each year and have to water every other day. My tap water is low in salt and bicarbonates so I do not have to use rain water. I just make sure that I am watering enough each time that water runs out the bottom. That helps keep the salt down. Salt water will move down since it is heavier than fresh water, but will move back up through capillary action as it dries up. I do not put down dishes to collect on the bottom of the pot because I want the salts to leave. Frequent light watering that does not drain out the bottom will cause salt build up.

I don't really care if the nitrogen is leach out, release out to the atmosphere, or used by the plant. When it is hot and dry and I am not getting any rain, I do put half the water in the pot and then add the other half with the solution. That way I know the mix is not too dry. The main thing to remember is the nitrogen is not going to remain in the container for long. In 30 to 45 days most nitrogen will not be available to plant, either being used up or leached out. Phosphorous is not like that and can only be added once a year. Potassium will also leach out but does not seem to be a big problem. Nitrogen and pH are the hardest things to manage. The rest seems to be fairly easy.

Thanks for the help, garybeaumont_gw! I wanted to ask you a question about Miracid. I know that I should provide them nitrogen weekly or biweekly. But, for example, if I decide to give them ammonium sulfate, every week, how often in general should I give them Miracid (1/4 tsp per gallon) during the season? Maybe a larger dose once a month, or alternative with ammonium sulfate every week?

I live in southern Quebec. I think the blueberry plant break dormancy around early May and our first frost date is around October 7.

I alternate with Miracid once a month. I would not double up on the N when using Miracid. Get in a time table of when you are going to fertilize and use one or the other. Fertilizing weekly will be pushing the blueberries, make sure you do not get a salt build up or get too acidic. Those will be your main problems along with getting too wet in the winter.

RD,

Most of the answers of your question has been already addressed by Gary. I just wanted to add some of my thoughts. Like RD mentioned, the purpose of soil in a container is to control the pH easily. Many blueberry growers like myself use soil-less medium (I use 5:1:1 composted pine bark mulch: peat moss: coarse perlite) and it is much easier (though there are few negligible downsides) to grow them in a pot rather than in ground especially your soil type, pH, water table, etc. Again, like RD said, whether you fertilize them with organic or synthetic fertilizer, they all must be broken down to the elemental nutrient to be absorbed. I would fertilize them only with organic fertilizers if I am trying to get USDA certificate for organically grown berries.

Growing blueberries in a container with ammonium sulfate PLUS other essential macro and micronutrients is essential for plants health. As long as you have full spectrum fertilizer whether it is synthetic or organic your berries will be nutritious even if you grow them in pots.

Talking about organic fertilizers, blueberry will be okay with cottonseed meal or blood meal for nitrogen and bone meal for phosphorous which are available in local garden stores all over the US, and I assume they are also available in Canada. Holly Tone is also okay in my experience but not the great one. There is at least one Rabbit Eye variety called Onslow (probably you don't have to worry about it as it would not grow in your region, my guess) do not tolerate cottonseed meal. The greatest organic fertilizer I liked are fish emulsion fertilizer (you can buy at your local garden center/big box store or you can make it yourself) with liquid kelp fertilizer like Mexicrop (probably available in your area). Combination of these two results excellent growth and berry production.

If you want to go with the synthetic route, I like Peters Professional Acid Special Fertilizer, 21-7-7. It is water soluble and has all macro and micro nutrients. The only downside is they have only one size (25 pounds) bag, no smaller packet. I don't use Miracle Grow's acid formula (also called Miracid) simply because they use potassium chloride. Blueberry don't like two chemicals nitrate nitrogen and chloride form of nutrient. Peters Professional Acid formula has potassium sulfate in their formula.

If you are using ammonium sulfate alone, you can have 1 teaspoon in 2.5 gallon water and can be applied once a week after berries are harvested till the end of August in your area (till the end of September in hot area like mine), If you use Peters professional, 1 teaspoon in 5 gallon of water and feed the plant ONLY twice a month. Peter's formula used both ammonium sulfate and urea, and urea has much higher concentration of nitrogen and that is why you need to apply very little and only two times a month or you will burn your plant). The advantage of water soluble fertilizer is nutrients are readily available for plants the minute you water them. Just make sure you don't over fertilize in any case and you have watered the plants very very well the night before you apply fertilizer or you will burn your blueberry plants. Blueberries are not forgiving plants for sure, unlike other plants, blueberries will show the fertilizer burn sign overnight. Good luck!

Thanks, inkfin!

What's the difference between:
Peters Professional Acid Special Fertilizer 21-7-7
and
J R Peters Jacks Classic No.1.5 17-6-6 Acid Special Fertilizer

Besides the difference in the numbers?

The later doesn't come in a big bag and seems afforable, though I would have to buy it from US.

You wrote that ammonium sulfate "can be applied once a week after berries are harvested till the end of August." How often would you apply it before harvesting the berries. I imagine every other week if you're using Peters Professional twice a month (which would equal to every other week)?

I don't think I can fertilize until the end of August because my first frost date is October 7. Shouldn't I stop fertilizing two months before frost just to be safe?

RD,

Coparing online labels of JR Peters Jacks Classic No. 1.5 17-6-6 Acid Special and Peters Professional Acid Special 21-7-7 fertilizers, major constituents seems to be very similar except the numbers so I would say either will work well for blueberries. In either case, I would NOT use more than 1 teaspoon in 5 gallons of water and I apply fertilizer in completely soaked soil every other week. I have already burned few of my blueberry plants by over fertilizing or without soaking the soil before applying fertilizer.

Before harvesting I do not apply ammounium sulfate at all but Peters Professional only once very early in the spring around when the new leaves are started and buds are swelling then I wait applying ammounium sulfate until the berries are harvested simply because too much of nitrogen promotes vegetative growth and also impedes maturing berries evenly. When the buds break I would apply bone meal or other fertilizer rich in phosphorous and potassium that promotes flowers, root, and fruits. Once the berries are harvested, then I prune the plants and feed with ammonium sulfate or Peters formula religiously until the end of September or I can go until the end of even October if the temperature is too high. I live in Texas zone 8B, very hot and long summer (we are still experiencing either triple digits or high nintes now), short and mild winter. Since I have not experienced your climate, I can't tell whether it is okay to fertilize until the end of August and 1 month is enough time to let the plants harden or need longer interval. Probably your area requires two months long period to harden the plants then you have to end fertilizing by the end of July? Hope you can find either of these fertilizers cheap somewhere. Usually Amazon and Ebay are good source but they charge unreasonably way too much than the actual cost. Good luck!!

Hey RD,. I'm curious about your blueberry plan. BTW I loved all the feedback on here and all your quest's. Do you kno what you will do? My curiosity is will you order bare roots or potted or both? If you do get blues, and I think you should, how many will you get? This past winter I got 12 rabbiteyes bare root from finch in NC. I put 8 in the ground and 4 in pots

as I look at my window and admire them, I can humbly tell you they are at EXPERT level lol . And what blows my mind is the 4 in containers are slightly better, bigger, greener and healthy looking than the ground ones.

im responding to you out of curiosity and also to tell you I'm an idiot and I'm growing them incredibly! They must be easy to perfect. But please don't worry about it. It's easy. And all the fun is doing it and learning as you go. All I did was test my soil which was acidic, I buy from reputable source. Dig big hole. Fill with 60 or 50 percent peat moss and the rest native soil, watered them a lot!!! Fertilize lightly every ten days giv or take, and prune after harvest. It's fun and easy.

This week is their 6 month anniversary and they almost tripled in size already . 4got to mention one died. It happens. Not worried bout it. I'm getting 12 more this coming year. Can't wait.

thanks for asking those questions and Thnks to all the feedback. I book marked this page. You guys made this page a very informative resource

Hi Otto Gsell,

I've had potted blueberry plants of different varieties since 2013 or 2014. The first two years, the plants did ok and growth was kinda slow, but not bad. I used an organic fertilizer (4-2-7). I applied it twice during summer. Kinda guessed the amount I should add to each pot. BTW, this is what was recommended to me by my local nursery as a fertilizer for my potted blueberry plants. That's why I now always come here to read what the experts suggest. lol

A week after I applied the fertilizer in spring, the leaves of my two blueberry plants got burned. Don't know if it's due to the fertilizer or the soil was too dry.

Ammonium sulfate is strongly recommended here, but I couldn't find it in stores, which was so frustrating! So I ordered it from eBay. Finally got it the third week of July. I applied it often until August 7 (two months before 1st frost date). Some of the plants have grown well. Two of them haven't grown at all, don't know why. I applied the AS too often between July 18 and August 7), so now the soil ph of my containers is getting below 4. So every few days, I water it with tap water to bring up the ph. This is my struggle with blueberry plants. lol

But now I know what to do for next year. I think I will follow garybeaumont_gw's plan.

I will apply Miracid in early May (when they break dormancy), and then, I will apply AS weekly. Early June, apply Miracid and again AS weekly. I will do this until August 7. Water enough so that it leaches from the container to prevent salt build up.

General consensus by forum members on the amount of fertilizer:

Miracid: 1/4 per gallon

AS: 1/2 per gallon

Urea: 1/4 per gallon

If the ph of the soil reaches between 5 and 4.5, I will apply urea instead of AS. Based on what I've read online, I'm not convinced that a bit of potassium chloride will cause any problem for the blueberry plants, so I will stick with Miracid. When I'm done with Miracid or if I have money to waste, I'll get J R Peters Jacks Classic.

I want to grow them organically, and I've read on other sites that it can be done with Hollytone. But on Gardenweb, many member states that synthetic fertilizer is the way to go with potted blueberries.

If you have any suggestions, let me know, though we don't live in the same zone!

Yeah I've read on here to that organic is not the way to go with containers. I use both in my containers. Lol. I'm a very new grower and I guess I just fertilize the same way I make my pasta sauce. A pinch here a pinch there of this and that lol..

I really hav have no idea what I'm doing but it is so much fun. In my mind I consider myself a scientist haha. I go outside , walk around, inspecting things. It's so funny!! Lmao

i scientifically mix my acid fertilizer into my blue bucket of water and presto, I go water them haha...

i really do do appreciate the pros on here who comment about fertilizer. It helps me a lot. I've been lurking on here for six months so I signed up last week. I got up the courage lol. The biggest way they help me is.... It reassures me that I'm doing the right thing, buying the right products, etc

btw I do use holly tone in my containers as well as miracle grow acid mix with water. They are doing great but I only put them in containers 3 or so months ago so who knows what will happen next year or next week lol

i love spending money so I will prob purchase the jacks stuff for Spring 2017 bec I hear a lot of good things about it. Umm my biggest challenge this year is and was weeds and drought . And my biggest goal next year is bird netting and weed controll!!! Wish me luck!

Ps. I really appreciate your comment back to me

Otto,

Just a caution about Miracle grow that has potassium chloride in its formula and Potassium chloride (muriate of potash) is used by some growers because it is cheaper than potassium sulfate, but blueberries are sensitive to chloride. If you compare the price side by side Peters Professional Acid Special 21-7-7 is cheaper per lb. compared to Miracle Grow Acid loving fertilizer. The only down side is Peter's professional does not have a smaller package.

Hollytone is good but not that great in my experience as it lacks all the micronutrients. Though it is little bit expensive, you would not regret fish emulsion fertilizer mixed with liquid kelp (like Maxicrop) and apply as directed on the level. Your blueberry yield next season will be much better compared to holly tone fed blueberry plants. Good luck!

Ink fin

ok thanks a lot

i will save that info and definitely highly consider it this coming fiscal growing year, 2017

i don't mind spending money on nutrients, food fertilizer for my blueberries bec it's most important I think. . The one thing I have been doing bec I learned it here is i use very low dose of MG acid fertilizer . And I write it on my calendar .

I only want to follow the best program for my blues and I couldn't do that without you guys helping me. I'm a Yankee from the north and I now live in upstate SC and I know no one here to help me. So I rely on you and everyone's help on here. This forum is so addictive haha

hollytone and acid MG was simple for me to understand this season. It's my first season of growing anything. If someone told me that I would love growing berries, etc as much as I love golf, fishing, football, etc etc.... I would say they are nuts!! But it's true. Prob my #1 hobby is my blues!!

this winter I will definitely dial in a great program for blues. I'm looking forward to it. BTW I'm finding many caterpillars eating/ hurting my bushes last few days. Very hard to see them . They camouflage into the leaf perfectly . And I'm really getting angry/worried. Found them on 3 bushes out of 17. I'm just picking them off and killing them. Could/should I spray?? I haven't searched on here yet about it.

alright thanks!!

Inkfin,

I found Peters Professional acid special at gardeners edge for $32.99 for 25 pounds. They say they have a special of $4.99 shipping until next Tuesday. If I understand you correctly it is all you use on your blueberries since it is ammonium sulfate with added micronutrients. That would make it easier if I am correct.

You may be closer to the right amount of fertilizer for maintenance. I get much more rain and have more leaching. Putting out 1/2 teaspoon in a gallon of water per week is really pushing it.

Otto Gsell,

I would use a BTK based insecticide. Spray it on your plants and it will take care of the caterpillars problem. Organic and kills them on the spot when they eat a sprayed piece of the leaves. Worked for me with a single application on my cabbage plant.

Looking into that now, thanks!!

Gary,

Yes, that is where I got my Peters Professional. Even with $4.99 shipping cost plus $32.99 for 25 lb bag makes only $1.52 per lb which I think is way much cheaper than Miracid (containing potassium chloride) at Walmart. BTW, occasionaly they send you FREE SHIPPING code on email, if you sign up for their email ad.

I would NOT recommend 1/2 teaspoon per gallon as this formula has both urea and AS which would make way too much nitrogen (21 parts nitrogen) and blueberry can not tolerate 1/2 teaspoon per gallon rate of that high concentration. That is pushing too much, IMHO. The matter of fact, I like smaller doses in frequencies. I have been using only 1 teaspoon in 5 gallons every other week and plants seems to be doing great. Most important thing is to soak the soil very well the day before fertilizing so that roots will not burn. Since you get good rainfall, apply right after rain stops if you see no another immediate rain in the horizon. If it rains and leaches out the nutrient, you can try 1 teaspoon in 4 gallons of water and see how it goes but definitely NOT 1/2 teaspoon in one gallon! Good luck!

Otto,

Talking about blueberries, I became really addicted with blueberries and collected over 30 different cultivars (both Southern High bush and Rabbit eye inclusive) with single and multiple plants in the past two years totalling 46 plants (all of them in containers) so far. My target is maximum of 50 plants and I am nearly saturated with blueberry plants, lol.

Spinosad (derived from the fermentation juices of a lowly soil bacterium called Saccharopolyspora spinosa) is a relatively new insect killer that quickly and safely controls a variety of caterpillars, beetles and thrips pests. To chemists, spinosad is a complex molecule known as a "glycosylated macrolactone;" but to gardeners with a hankering for safer products, it may be a godsend.

Bacillus thuringiensis, known for years to savvy gardeners as "Bt", has been a standard weapon for the war against caterpillars. As an insecticide, Bt is a safe, selective product for caterpillars. However, Bt lacks staying power. Instead of Bt's one or two days' residual, spinosad keeps killing for up to four weeks. In addition, spinosad kills thrips, which Bt doesn't faze. If you grow citrus and have leaf miners problem, spinosad takes care of that as well. If you have fire ants problem, spinosad takes care of them as well. The only downside is spinosad also kills honey bees, the pollinator for plants. It is recommended to spray spinosad either very early in the morning or late at night.

inkfin recommends fertilizing blueberry plants every other week, while garybeaumont_gw suggests once per month. My understanding is that blueberry plants don't require or like too much fertilizer, so what would be the best frequency when using a synthetic fertilizer like Miracid or Peter?

Ink, Thnks for the info!!

oh yeah I'm addicted also! Junkie!! Everything adds up also. Containers, soil, fertilizer etc... And then I find something better and off I go. Better pots better soil better fertilizer etc lol . Oh and better plants haha. Now I need the sweetcrisps of the world and 3 of each variety.......minimum hahaha

im a new boot blueberry junkie and proud of it. But it gets so confusing. I never cut back or pinched the tips of my huge new growth over the past 6 months but I think I still have 4 to six weeks of growing season left here in northern SC.

I might do it tmro but not sure if I have enough time for the shoots to do there thing so to speak, bud out or whatever it's called. Any suggestions?? Or should I let it be and learn from my experience and or mistakes??

ok spinosad. I check it out. Thanks!!

Ink,. I'm currently trying to figure that out now. I need suggestions also. In a perfect world I would like to have 3 NHB in one variety and 3 in another.... total of 6 NHB . I would like 6 or 9 SHB plants. 3 varieties ,. 3 of each variety

Im not sure what I will do. Been pondering for about a week on this. It could take some time to figure this out lol. I can't think of all of the varieties that I was pondering . Some SHB , , legacy, o'neil misty sweetcrisp.

NHB, blueray

dont want RE. I have about 17 ... But I might get ocholockonee lol. For a late ripened RE

i figure this is a big decision so I reckon lol I need to take my time... reckon lol

i have been studying on best SHB for zone 7b.. It would be great to see some replys that could help me out. taste is most imp. ( if I can do well with it is important also ).

My my heads been spinning about this. Hehe

RD..... Sorry for highjacking your thread. Any luck with fert plan/procedure ?

Otto,

Now you know how I ended up hoarding so many plants in just two years. I read blueberry info on line and felt every variety is good and I wanted them, lol. I am in Texas zone 8B so no NHB for me but I wanted very early variety (I have the earliest ripening variety to pick berries in mid March) and I wanted very late variety (my latest variety is mid to end of July) and I wanted in between variety. Selecting blueberry is not easy but you can narrow down to few depending upon your taste and demand. There are some tart, some sweet, some very sweet, some very flavorful, some bland, and some very crispy and some very soft, some very productive and some so-so. I like crisp so I got sweetcrisp, I have lots of them now. However, sweetcrisp requires only 200-300 chill hours and that means it may bloom too early in your zone, then berries will be destroyed by late frost unless you can protect them from late frost. Probably high chill varieties like Legacy will do very well in your area. Ocholockonnee requires high chill hours and I have heard all good things about this one, might do well in 7B. I want to try this variety some day. There are so many to chose from and my head spins too but fortunately I have room for only four more ;-)

Haha ink. I hear ya!! I want same thing you want. As early as I can get and as late as I can get and tons in between. There's always room for more! Lol

yes I'm beginning the process of narrowing them down. However I really don't kno where to begin. So I will keep reading and prob ask quest's.

I like like sweet and tart. Dislike bland. BTW i want star I think. I'm going to put star on my list. Oh about sweetcrisp and others similar to that....... Yeah I guess I can cover a few bushes from frost. Decisions decisions

zero caterpillars today,. I will be looking hard this week. I was on vaca last week Atlantic city, nj. When I got back I noticed them. Man do they eat the leaves!! Anyway thanks for the reply.

Otto Gsell,

I haven't applied any fertilizer to my blueberry plants since early August due to frost in early October. I'm done for this year. I will start next year in May.

Otto,

My earliest variety blooms in mid November and I must protect them from frost at any cost to harvest berries in mid March (very unusual)! If you can protect the flowers and berries from frost, no other blueberry variety tops sweetcrisps taste. I have few extra sweetcrisps if you can't find else where. I might have couple of other SHB varieties that might do well in your area, PM me, if you are interested. I do not have star and don't plan to have it simply because drawbacks with Star are the susceptibility to botrytis during wet springs and fruit cracking with heavy rains during ripening.