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Blueberry container mix and fertilizer questions

7 years ago
last modified: 7 years ago

Hello all,

I'm planning on growing some blueberries in containers and have been perusing the copious amounts of information on this forum to design my own plan. I was hoping the experienced gardeners here could take a look and let me know if there are any potential problems with what I intend to do.

Location: New York City, zone 7A

Plants: One year old stems of Pink Lemonade and Peach Sorbet (brazelberry)

Container: One 10 gallon Smart Pot (made of fabric), one 20" wide, 10 gallon plastic pot

Potting mix: I'm planning on using a variant of the 5-1-1 mix using Safe-T-Sorb (calcined montmorillonite clay, like Turface) instead of perlite. This is just because I have it on hand, it helps retain moisture, and it's known for reducing pH in aquariums, which I figured would help with the blueberries.

Fertilizer: Since, as far as I'm aware, the 5-1-1 mix doesn't have many nutrients, I plan on mixing in some Down to Earth Acid Mix (https://www.downtoearthfertilizer.com/products/blended_fertilizer/acid-mix-4-3-6/) with the soil. This contains calcium and magnesium, so I take it I wouldn't have to supplement with gypsum and epsom salt.

I've also seen many people here recommend ammonium sulfate to speed up growth in young plants, so I would do as fruitnut suggests and water them weekly with a tbsp of AS in 2 gallons of water.

Specific Questions:

1. Would this potting mix be usable for a few years, or will it degrade and need to be replaced every year?

2. Are all nutrient needs met with this plan? Aside from nitrogen, I would be relying on the DTE Acid Mix above for most of my nutrients. As it's an organic fertilizer, which I've read breaks down inconsistently in containers, would I be better off with a synthetic controlled release fertilizer? If so, what brand/type should I use?

3. I've heard that fabric pots act differently because the moisture can be wicked into the ground, so they do not have drainage problems. Given that, would the 5-1-1 mix be a bad choice, and should I go with something more peat-heavy instead?

Thank you for reading this long post, and for any tips/advice you may have. I'm very new to this forum and have been trying to process a lot of information in the past two days, so it would be great to have some feedback.

Comments (17)

  • 7 years ago
    last modified: 7 years ago

    I've been growing blueberries in fabric pots using a peat/compost/pine fine mix going on 3 years. I've used pH adjusted water and Vigoro azalea fertilizer twice annually but will be adding in AS dissolved in water this year. While I can't tell you how long 5-1-1 would last in a fabric pot, my mix appears to still be holding up fine. Blueberries have pretty fragile roots so I would imagine the root trauma of repotting annually could be detrimental.

    Just realized North Mississippi where I live and NYC are both in 7A, I would have never guessed.

  • 7 years ago

    Thanks for the info! Yeah, it doesn't make much sense to me because on average, NYC is so much colder than other areas listed as 7A. I imagine it's because the USDA zone map only considers average minimum temperatures, which leaves out a lot of other relevant information, like how long winter lasts here.

  • 7 years ago

    Good luck on your project, I can't help on the container stuff, I grow my blueberries in ground in Louisiana, though I am growing Pink Lemonade, and find it an interesting alternative to standard blueberries. Mine were planted in ground as bare roots about 26-27 months ago, and a couple of them are already over 4 ft tall.

  • 7 years ago

    I've grown blueberries in pots for years with great results. Sounds like you have a good plan.

    -Yes, your mix will be good for a few years, and you will be potting up before the mix wears out.

    -Sounds like your mix is healthy, but you still need fertilizer with the ammonium sulfate. I use MG Shake and Feed at the beginning of the season. It's a great CRF for containers. Osmocote is another one. I also use a weak/diluted MG liquid with my waterings during the season. Your plants will grow fast.

    -The 511 is a great choice. It will break down and become more water retentive over time. Blueberries don't really like wet feet anyway. Lightly moist is perfect. I ended up with my blueberry plants in food grade 55 gal drums cut in half. Fabric pots might dry a little quicker than a solid pot, but it's not a problem. Just check moisture levels daily, and don't let them get crispy.

  • 7 years ago

    NYC is zone 7B. Never used a fabric pot. But I have eleven blueberry plants in my garden here in Brooklyn NY 7B in ground and in containers for many years here - solid bearers - bugs ignore them - birds too - absolutely no work - just a little pruning. Various varieties like my favorite chandler. I would NOT use a 5-1-1 and use a high peat mix with some perlite and whatever you have handy in a container definitely with mulch on top. Blueberries do like wet feet, the old saying goes you can't overwater a blueberry.......they dont need too much sun either, they're naturally an understory plant. Dont know about fabric pots but I left ones I was giving away after dividing a bush type in one gallon nursery pots all winter and they did fine in garden soil exposed to the cold in a tiny container. I usually add hollytone acid fertilizer and a touch of sulphur twice a year - avoid ammonia its toxic.......

  • 7 years ago

    a 10 gallon pot is ridiculously oversized too.........for a one year cutting

  • 7 years ago

    Please do more research on blueberries. They do not like over-wet soil. The birds where we lived had a field day with our blueberries, and we had to make coverings out of cheap wedding tule, that worked well.

  • 7 years ago

    The birds and squirrels don't bother mine for some reason, definitely a goto crop here in 7B NYC..... and I don't have to use coverings.....I wont be researching what I have already grown for 20 years. a 5-1-1 mix in a 10 gallon pot for a one year old cutting makes no sense to me.

  • 7 years ago

    Blueberries can take a lot more soil moisture than one would think. They often grow in bogs in the wild and a local longtime blueberry farm (now on the historical register) where I worked summer during high school is actually planted on a bog. And still very productive after nearly 100 years!!

  • 7 years ago
    last modified: 7 years ago

    I was suggesting the OP do more research, one thread on one forum isn't enough. Growingfruits.org is excellent. Everything I ever read about blueberries, and from my own experience, over-wet is no good....damp is good....dry is no good unless plants are dormant, and even then, keep slightly damp. The key with blueberries is to not let them dry out when growing, that doesn't mean over water. Well drained soil is also good. I never heard of a blueberry bog. Whoever has no bird problems with blueberries is fortunate indeed, and I agree that a 10 gallon container to start out is way to big. Start small with the pots, and pot up when necessary.

  • 7 years ago

    It would be hard to over water in a fabric pot, my blueberries in fabric pots weep moisture all the way around when I water them. I have had drought damage when I failed to water them for about 2 weeks in the summer last year but they dropped their damaged leaves and rebounded quickly. Bird are also a problem here, I had to build a net house for my plants or the blue jays would have taken every one of them.

  • 7 years ago

    Good point about the fabric pots being hard to over water.....that goes double if the mix drains well.

  • 7 years ago

    Thanks for all your comments. Based on what you've said, I decided to get 5 gallon fabric pots for the smaller blueberries and add Osmocote Plus to the potting mix.

    Adam, could you tell me what size fabric pots you use, and what size you recommend for one-year plants? I'm concerned that 1) a smaller fabric pot would dry out much more easily, especially with a fast-draining mix like 5-1-1, and 2) that repotting from a fabric pot would be extremely stressful to the plants because the roots are tangled up in the fabric.

  • 7 years ago

    I've been successfully growing blueberries in pots for nearly 10 years; I use anything from cat litter buckets to double walled pots (my preference). My soil mix is roughly 75% peat mixed with about 25% chopped leaves, and I top dress them with more leaves every fall when I mound leaves around the pots for winter. I rarely fertilize them and get plenty of berries.

    I made a netting house out of an old gazebo that I rescued and premium bird netting (not the cheap bird netting, birds get tangled in that and die I discovered). This keeps both birds, raccoons and possums out of the fruit.

  • 7 years ago


    20 gallon vivosun fabric pots off amazon. I know 20 gallon is ridiculous overkill but I didn't want to have to water daily or repot in a year or 2. These are going on 3 years now and have yet to have a bag handle or seam fail (not sure why but it won't let me upload the picture in the correct orientation)

  • 7 years ago

    That's a nice looking plant! I definitely understand your reasons for planting in a large pot. Aside from cost, is there any reason not to do it? I know too much water retention can occur with oversized containers, but it shouldn't be a problem with the 5-1-1 mix.

  • 7 years ago

    They get pretty heavy and cost a little more but the space taken up by the plant is as wide or wider than the pot so size isn't really a concern. Another positive is I've never had a 20 gallon blow over in high wind but have had a 7 gallon blow over.

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