Larger the better. Blueberries can develop pretty extensive root systems. Plus, I hate having to repot. Mine are very large terra-cotta (both the real thing and plastic versions) that are about 2 to 2 1/2' feet tall. Not sure the gal amount - probably about 25 gals?? I never transplant them until I think the soil is exhausted. And that would take several years. I try to never use black plastic pots, as I think it heats up the roots way too much here in my part of S. Calif. And, all my blueberries get afternoon shade as well and love that. Once you have the soil prepared, just remember never to let them get dry. That will spell sure demise for young blueberries.

Patty S.

Here is a link that might be useful: Dave Wilson Nursery: Growing Blueberries in Containers

I grow mine in 10 and 15 gallon black smart pots. Those are the felted fabric pots. I was afraid that the soil would heat up too much but they did much better in the heat than the plastic pots. I use 1/3 coir, 1/3 peat, 1/6 perlite and 1/6 sand for potting with a handful of kelp meal. I try to water with pH adjusted water. I move my pH 8.5 water to around 6 to 5 with pH down.

My buddy inherited some that were planted in large plastic garbage cans. They are huge and old and quite productive.
Following that lead, I dug up and put my 2 plants in the largest plastic pot I had, which has got to be 30 or 40 gallons. Got that pot at a rummage sale. It is a huge pot but not as big as a garbage can. We're in the Bay Area.

Mine were productive in 10s for 3 years. I put them in the ground this year. They are tougher plants than I thought they would be. You can also bury the pot in the ground to keep the roots cooler and more moist.