If available in your location, an acid planting mix (sometimes called rhododendron, azalea and camellia soil) would shortcut the entire operation. These tend to be heavily bark based, which is an excellent starting point. I grow a lot of acid lovers in containers and that is a soil mix I use frequently as the base for my media.

Otherwise, I'd suggest the 5-1-1 recipe - 5 part bark fines, 1 part peat or coir and 1 part perlite or pumice. Go very lightly on any lime additions (but I do recommend some......you want the pH to be right around 6.0 or slightly lower). This will provide a durable, long lasting mix that provides both the fast drainage and aeration necessary as well as adequate moisture retention.

I'd also check the pH of your irrigation water. It may also need acidification to keep the blueberries happy long term.

gardengal, thank you for the recommendations. I did try to find the acid plant potting mix but there seems to be none in my area. I looked at two big box stores, my local agricultural store and called three different garden centers all in within a 20 mile drive but nothing. Pine bark fines are also hard to come by. There's plenty of pine mulch and pine nuggets. Can one of those substitute the pine bark fines?

What if I use espoma soil acidifier to some regular potting mix along with peat? I know the soil acidifier takes time to work but if I go with 50% peat, hopefully that will provide the plant with enough acid this season.

Good call on the pH of my tap water. I'm sure that could bring the soil mix closer to neutral over time.

Ken,

I'm in southern NH, border of zone 5b & 6.

The 18inch container is a self watering container with a 1 gallon reservoir at the bottom. I have other 40 gallon grow bags that I grow tomatoes and eggplant in so I have a good idea about the water requirements although I'll have to adjust to the blueberries water needs. I've read that frequent, shallow watering is better for blueberries in containers.

I would be cautious about adding much peat to the mix. Because of its fine texture/very small particle size and its ability to absorb and hold water, you run the risk of compromising good drainage and aeration and a subsequent elevation of the perched water table. This can lead to root issues and plant decline. If anything, I'd focus on adding more bark fines rather than any peat. Sometimes these are sold under a label of "soil conditioner" but you need a size that is pretty small......about 3/8 of an inch. And frequent shallow watering is not recommended for any container plantings. When you do water, water fully so that it drains freely from the base of the pot. Frequent light watering is usually recommended by those using an inferior media to avoid the mix becoming waterlogged.

I can't find any bark fines in this area. I was actually out at three different places this morning and called two more and no bark fines. After reading your post, I called back to ask about soil conditioner and explained that I'm looking for bark fines that might also be labeled as soil conditioner and three places said they had soil conditioner but recommended peat moss, compost, manure or saw dust. One place said they carried bark fines but they didn't sell. One guy recommended buying some of their pine bark nuggets (which I already have) and mow over it with my lawn mower to break it up.

I also called my agricultural extension office, they said 50% peat and 50% potting mix should be great because the potting mix has perlite and chunks of bark that will provide enough drainage. They stressed using acid loving plant fertilizer starting next spring. They also suggested NOT pinching off blooms. She said I'd just be wasting perfectly good future blueberries. Plants are probably 1-2 years old already and will grow a strong root structure this year and you'll get plenty of blueberries next year. This goes against other information I've read online. Looks like there's different ways of doing things.

Thanks for the info!

"they said 50% peat and 50% potting mix should be great because the potting mix has perlite and chunks of bark that will provide enough drainage"

Sorry, but this is just not true........unless the bark, perlite and peat are in the proportions I referred to with the 5-1-1 mix. It may work for a single season but at the end of that season the 50% peat (added to whatever peat exists in the potting mix) will have collapsed and compressed down into a soggy muck.

Unfortunately, you have been talking with folks that know very little about successful container gardening.

Right, as I said in my original post:

"There's seems to be a lot of conflicting advice online and even amongst agricultural extension offices at universities around the country. Some recommend a 50% peat/50% potting soil, some recommend 100% peat, some recommend 1/3 potting soil for acid loving plants like azaleas, 1/3 peat, 1/3 pine bark, some recommend 2/3 peat, 1/3 shredded bark and another recommends any good quality potting soil with a soil acidifier and an acidic fertilizer mixed in at time of planting. Some people have success with the high peat growing media and other say it killed their plants due to the peat compacting and suffocating the roots. Some people say don't use a potting mix for various reasons."

It sounds like you're in the lower peat camp. But I've read about people who grow successfully in 100% peat. As long as you consistently provide nutrients they will thrive. Someone on this forum apparently grows blueberries in containers with 50% peat, 50% potting soil for 10 years successfully. I also read a study, I believe from University of Florida, who concluded that high amounts of perlite can be detrimental to blueberry growth. Other say 50% peat, 50% coir and your blueberries will be in good shape.

Now I'm trying to decide, pinch off blooms or let them become blueberries. And, should I fertilize at time of planting or wait until next spring because there's plenty of fertilizer in the nursery soil for this year. There's a good case to be made on both sides I guess.

Unfortunately I can't find bark fines anywhere and I have to plant these blueberries in something. Maybe I'll get lucky. When I first started container gardening, I used the same potting soil for tomatoes three years straight with zero problems other than some early blight. They were planted in some standard potting mix. I found out later that the "rule of thumb" is to not use the same potting mix for tomatoes. I just added fertilizer and water. I get 20-30lbs of tomatoes off those plants which I'm happy with. If I can 2-3 pints of blueberries per plant I won't complain at all.

If you put the effort into it, you can grow blueberries "successfully" in just plain old sand! But there is a difference between what some consider successful....just keeping the plant alive or providing the growing conditions for it to thrive.

I would NEVER recommend growing anything in straight peat......unless it was more sphagnum moss. And most especially in a container where fast drainage and good aeration are essential. High percentage peat mixes are the anathema of that.

Have you ever done much container gardening? I'd suggest you read some of the highly informative threads here about quality media choices and the need for frequent and proper fertilization. It is far better and much more detailed info than you will find on any extension service website or publication.

StartHERE. And follow up with this:fertilizing containerized plants

I've had ~10-12 blueberries in pots for many years because they just won't do well in my soil, even if amended - some of them more than 10, I would say - and I always plant them in peat mixed with some homemade leaf mold - maybe 75/25 (+/-) - and some handfuls of sand as well. They seem to like wider than deep containers - like used tree pots. They get topped off with more peat/leaves every couple of years, and I toss some generic fertilizer on once a year or so. I had some "blueberry specific" fertilizer at one time but didn't really notice an advantage to it.

They are not on a patio, but in a corner of my yard and rarely need watering - only if we have a long dry spell like we did last summer, when everything needed water.

I heap leaves or straw around the pots for winter protection.

Based on previous comments, perhaps blueberries are rather more forgiving of soil mix than we think - just so long as their medium is acidic enough for them?

gardengal-

Yes, I suppose we all have a different definition of success. Like I said, I'd be perfectly happy getting 2-3 pints of blueberries per plant. Others might expect 10lbs.

I'm only about 5-6 years into gardening in containers so I don't have as much experience as you and others here. I grow tomatoes, eggplant, winter squash, salad greens, kale, cabbage, radishes, fennel, Swiss chard in containers. I mostly use self watering containers and put a strip of fertilizer in at time of planting. I grow potatoes and cabbage in grow bags (smart pots) I've done pretty good overall. Last year I got 25lbs of tomatoes on a Cherokee purple plant but only 12lbs on a Jetstar plant. I was happy with both because that's plenty of tomatoes for two people. I've certainly had a few failures along the way. Like learning about squash vine borers the hard way.

This is my first time planting berries or anything that prefers acidic growing conditions. For some reason this seems to be a bit more complicated than other things I've tried to grow. I usually don't have a problem with soil.

Appreciate the input and links.

raee-

Thank you for the input! I have 20 inch pots so hopefully that's enough room for the roots to spread out.

Do you think the 50% peat, 50% potting mix will be suitable and acidic enough for blueberries? Also, do you fertilize in the spring? What are your thoughts on pinching off all the blooms for this year?

Do you think the 50% peat, 50% potting mix will be suitable and acidic enough for blueberries?

I really can't say! I only know my own experience. I think I started with the mostly peat after my first few attempts to grow in my regular potting mix + miracid failed (I probably didn't keep up with the miracid enough). Then I think that I read somewhere about using mostly peat. So all I know is that mostly peat with some decomposed leaves works for me! Oh, maybe I toss in a trowel full or two of compost/soil mix from the surface of the garden too (that's another no-no I guess, but I thought to add the good microorganisms from the soil/compost. And worms).

I am also inconsistent with fertilizing - not necessarily in spring; It tends to rain heavily here in March - April, and this year still in May, so I think the fert would just be mostly washed out. I tend to fertilize when rain isn't so heavy/frequent but before our dry spells in late July-August. One rule I do follow is to not fertilize after August, don't want to spark new growth that won't survive winter.

If you are using soil that has fertilizer mixed in, you shouldn't add any more at planting. I personally would not buy the potting mix with fertilizer - my impression is that they are meant to encourage lots of bloom in annuals more that good solid growth for perennials. So if no fert in the soil mix already, you can add slow release fertilizer (I use Osmocote as directed on the label).

If the plants you received have well developed, not pot bound, root balls I wouldn't worry overmuch about removing any blossoms, if they should produce any after being transplanted. But I wouldn't expect much berrying. Removing the blossoms does encourage energy to go to the root development, so that is a good thing.

raee-

Thank you for the information. I was in Maine a couple days ago for my job and I stopped by a popular garden center close to where I was. I was specifically looking for the elusive "bark fines" or Azalea soil mix. Someone asked if I needed help and I told her what I was looking for. She asked me what I was planting and she brought me over to a woman watering some fruit trees. Turns out she used to be co-owner of a blueberry farm in Maine for 25 years. She has since retired and works at the garden center a couple days a week. She still grows blueberries at home in the ground and containers. She said the high peat potting mix will be fine because the root system of blueberries is shallow. They will not grow deep into the container where the peat could potentially be compacted over time. She said a wider container is better than deeper. She said the bigger concern is planting in something that's too sandy or in something that doesn't retain enough water. The roots won't spread out away from their original soil you bought them in and won't grow big. The plant will grow very slowly or not at all. She said keep a 2-3 inch layer of mulch and stay on top of watering. No fertilizer the first year but next year fertilize once in the spring with 21-0-0.

And she also said unless you're a commercial blueberry farmer and planting high bush blueberries and need 8lbs of blueberries per plant, there's no need to pinch off blooms at time of planting. I'll get a small crop this year but more next year as the plant matures and roots fill in the container (but also depending on environmental conditions, watering etc...). She said if growth of the plant is slow, it probably has to do with not breaking up the root ball enough at time of planting and/or having soil that doesn't retain enough moisture.

I know you're probably aware of a lot of this information already but I thought I'd write this out in case other people search for similar information about growing blueberries in containers.