Secondary question ... is there a certain soil people get for container blueberries? I dont normally need to do much of anything to my natural soil, but that's in a garden setting with northern high bush varieties. Will that work well mixed with aged compost? Or do I want something more like potting soil?

I thought I had responded to this before but guess not :-) Sunshine Blue will grow happily in a 10-15G container but you can go a bit larger if you like. And if you are growing it in a container you must use a container or potting soil - no garden soil, no compost. Look for something recommended for acid loving plants, often sold as rhododendron, azalea and camellia (RAC) potting soil.

Thanks! We'll pot them up in some 16" pots ... should be about 10 gallons.

We use Miracle-Gro potting mix for our fruits, vegetables, and herbs. They don't have an acid version and recommend using the all-purpose soil for blueberries on their website, so it seems like that would be a viable option. Has anyone grown blueberries in Miracle-Gro? Would you recommend adding any mix-ins or just using as is? I do have some Holly Tone, or equivalent, in the closet that I could add down the road.

All of my potted hardy blueberries have done will in a mix of peat (85% probably), some leaf mold and touch of garden soil. They live outside.

I have found the 5 gallon cat litter buckets, with drainage holes drilled, to work very well for plants (such as a fig) that have to be carted in and out of the basement.

I've always been told to fit the pot to just one size larger than the root ball, and upsize as the plant grows (to avoid more moisture surrounding the root ball than the plant can deal with, I think) - but Gardengal would know more than I about it.

Well, I would never recommend Miracle Gro potting soil for any containerized plant. It really is a very inferior product and these forums are filled with those who have had issues with it. (And I would caution against believing 99% of what they say on their website!!) You may get away with it for a single season annual crop but for a more or less permanent planting like any shrub - the blueberries - or trees, you will not get the growth and performance from the plants you should expect. It is too fine a particle size, retains too much moisture and will collapse and compress, resulting in a high PWT that will affect root development.

By the same token, garden soil and OM like compost or leaf mold are not advised for containers either. For an acid loving plant like blueberries to grow well in a container, you need an acidic soil mix. Many companies make something that fits that description that would be far better than anything MG produces. Or you can make up your own potting mix. Something like the 5-1-1 described in detail on the Container Gardening forum but without the addition of lime to neutralize pH would work.

Holly Tone will work well for inground blueberries but not for those being grown in a container. There are very valid reasons for this but involve a discussion that is beyond the scope of the OP's question.

So 16" pots came in and are enormous! The online picture/description was a bit confusing because it seemed to be trying to describe multiple sizes. (We were expecting shorter than they are wide, and these guys are deep.) Well, there's no way we'd be able to move those bad boys in and out for winter when full of soil, so they will be getting herbs or annuals if we use them, but since the back garden is only half finished for plants anyways, that might work well.

We've ordered new pots that should be more rationally sized for moving around ... hopefully; the new ones will also be self watering.

Looking for acidic potting soil, I come across things like this:

https://www.kellogggarden.com/products/gborganics/gb-organics-acid-planting-mix/

But it lists a pH of 6.0-7.3 ... that's a) barely acidic, and more neutral than what most places recommend for blueberries (closer to 5.0) b) not really any better than normal potting soil.

This one doesn't describe itself as for acid lovers, but it lists a pH of 6.2, which is as acidic or better than the one above:

https://coastofmaine.com/product/barharbor/

Could I mix it with something like peat moss to bring down pH and have that work well? With pHs around 4 for sphagnum and 6.2 for the Coast of Maine soil, mixing half and half would give me about the 5 pH recommended for blueberries, but would that be a good consistency for growth or would I want to add something like bark mulch, too?

If not something like HollyTone, do you recommend a different fertilizer? Or is it unnecessary in general ... I'll admit my bushes in the ground don't get anything other than some watering when it's hot and dry.

Thanks! That also explains why the ones in the groubd do so well without modification. I didn't think our soil was that acidic.

This thread is awesome! I got myself a 2 feet Duke blueberry about a month plus ago. It has some green and woody canes so maybe 1.5 to 2 years old. Not too sure. But I'm a newbie to gardening so I just planted it in a potting mix suggested by the garden centre. https://www.seasoil.com/container-complete-sea-soil.html The potting mix is primarily composed of composted fish waste and forest fines, and has a pH of 5.5.

It retains water too well IMHO so I added in some perlite after I took my young tree out again to loosen up the root ball a little after transplanting. I was afraid that I might have killed it but it survived my rough handling. I tested the soil pH today because I'm using tap water that has a pH of 7.5. The soil pH today was about 6.0. I'm using the Miracle Gro fertilizer for Azaleas, Camellias and Rhododendrons (just once). It says to fertilize every 7 to 14 days though. Isn't this too often?

Also, how do I know I need to repot it to a bigger pot in future...? Right now it's in a 14 inch pot, so maybe 7 gallons or so.

"Isn't this too often?"

Nope! Because plants grown in containers need such frequent watering, any nutrients that are present are quickly leached out. And standard potting soil has no nutrient load of its own. So frequent fertilization - generally in a dilute form - is necessary. "Weakly, weekly" - no more than half or quarter strength applied on a weekly basis or with every other watering.

With that sort of bagged potting soil (really more of a soil amendment than a proper potting mix), it should be replaced annually. It is not textural or durable enough to not collapse and compress after a single growing season. So you can judge at that time how much larger a container you need to move up to.

Just an FYI but few permanent container plantings in my garden are in anything smaller than a 20G container, but it depends on the plant :-)

Thank you gardengal! My Duke is still young, only 2 feet or so. The potting mix I use is highly water retentive... so I'm not very happy with it. It compacts quite a bit. I think I will repot next year spring because I've already taken my Duke out 3 times.

What kinda potting soil would you recommend for blueberry trees? Or can I mix in promix hp ( https://www.canadiantire.ca/en/pdp/pro-mix-mycorrhizae-growing-medium-60-lb-0594892p.html ) and more perlite into the same potting mix (cos I still have a bag left) to achieve more porosity and stability in my growing medium?

Bark fines - if you can find them - better than perlite. And add in a signification percentage.....50% or more of the total volume.

The thing is, it's very hard to find uncomposted/composted bark fines here in Vancouver. And I see a lot of Vancouverites asking around on other forums as well..

Look for products labeled "soil conditioner'. Nine times out of ten, it will be comprised primary of bark fines.

Thank you :)