Don't try to keep the plant in that small of a container. Buy a half whiskey barrel planter, fill it with 1/2 non-peat based potting soil (not the type with built-in fertilizer) and 1/2 peat moss (or choose one of the various recipes on the web), plant the blueberry, and put at least 3" of mulch on top.

Mine have been in 15 gal pots for about 5 yrs. These are about 15-18 inch pots. They have done great. I've had huge crops. I've had to prune and thin to limit the crop to 5-8 lbs per plant. The plants just keep getting bigger and are now about 4ft tall by 4ft wide. Since they are doing so well I have no plans to repot.

Yes, you could repot in the same pot. If you aren't getting good crops, a bigger pot won't solve that. A repotting might if the soil is the problem.

Are you getting good growth? How big are your plants?

The Fruitnut

DJofnelson, I would really rather not buy more pots at this point, and also, half whiskey barrels are very difficult to find, not to mention expensive, but thanks for your suggestions.
Fruitnut, good to hear my pots are big enough. I have some 22" pots, but they have roses in them. I am getting a lot more berries that I have in the last 3 years, but they are pretty small, and certainly NOT 8 lbs per plant! Geez, I wish...!. I have two different cultivars, both dwarf, one is smaller at 1-1/2 ft tall; the other a bit bigger, maybe 2 ft tall. They seem very healthy, and are even flowering again (or are they supposed to flower/fruit continuously until fall?). I check the ph of the soil a couple of times a year, and it's consistently between 5-5.5. I use a meter that I paid $60 for, so I'm hoping it's accurate (one of my late-night on-line catalogue binges!).
If, in your opinion, you don't think I need to repot, then that's great, I'll just top-dress with peat and compost/worm castings in the spring, and sulphur in the fall, which is what I've been doing. I guess I just figured after all this time it might need a little something more:)
Judith

Judith: My feeling is that if your plants are healthy and growing adequately, then they don't need repotting. Sounds to me that your plants are just naturally smaller and less productive than mine. If you try more cultivars, you don't need dwarfs to be successful with potted culture. It is easy to prune any cultivar for pots.

The Fruitnut

Judith, I realized after posting that 20" was a much bigger pot than I'd originally thought. Fruitnut knows a lot more about potted culture than I do, so I'd certainly take his advice. Also, I agree that the 1/2 barrels are expensive (I found mine at a local yardsale). You can also use large wooden boxes/crates with drilled holes. If you can find something larger in the next few years, I'd assume you would get larger crops and you would certainly lessen the chances of the pots going dry and keep the roots cooler.

Thanks Fruitnut. I will leave them be. Of course, now that you've given me the go-ahead to pot up more blueberries (since size doesn't matter) I am doomed:)
Thanks, Dj - I would LOVE to get my hands on a few half-barrels, for both my roses and my berries. I'll have to start frequenting all the garage sales around here..
Judith

Judith. You could look around in different places in the fall. You get good deals then. I had the opportunity to buy all I wanted from Home D.a couple of years ago in the fall. But I was feeling cheap that day and only bought four. they were 14.00 each. I have ten mostly high bush in 15 gallon containers. they are growing very well in the fast 5.1.1 mix I learned to make over in the container forum. Tapla "AL" knows his stuff. good luck. filix.

Hi everyone,
JUDITH,you should read up on bonsai, root pruning potted plants, as well as root bound plants this winter. You con use 5 gallon buckets for small plants, they are deeper then most pots. You also can use 55 gallon drum, cut in half, vertically or horizontally. I am not disagreeing with Fruitnut. I just think only you can see your plants day in day out. Knowing whats happening will help you response quicker. I repot my plants every year to keep the root ball from choking it self. this will not happen to every plant.

Thanks Felix, I will take a look around for some fall sales; you never know, I may be lucky. And yes, I have read a little about Al's container mix. I don't seem to be able to find all the ingredients though. I will keep looking.

Hi Jolj, I think I will leave them for the time being as they look healthy. But in the future, if production drops, or they just don't look happy, I will consider repotting.
Judith