I grow almost everything in containers. The only blueberry I would grow in a 12 inch deep pot, like a 5 gallon bucket, is a wild blueberry or huckleberry. You can grow any variety of blueberry in a container, but a 'highbush' blueberry grows to 7 or 8 feet tall with a 4 to 6 foot spread. A 'lowbush' variety (my recommendation) is 2 to 4 feet tall with a 2 to 4 foot spread.
Although blueberries do have a very shallow root system, the roots spread outward way past the dripline of the plant at full width.
So, You really need a good wide pot (at least 20") for the roots, and you need a 2 foot depth for the height of the plant. (Think about even a 30" bush in a 12" deep pot and I think you'll see what I mean).
Lastly choose the right varieties for your climate/zone. And choose 3- one each of an early, midseason and late variety- spaced 3 to 4 feet apart. You need these because they need to cross polinate with each other.
You'll be in berries all season (after you wait for 2-3 years for the plants to get established).
Growing blueberries in large pots is a great idea though, it's easy to adjust and keep the soil as acid, (lowbush likes a ph of about 4.0 to 5.0) as it likes, without effecting your other soil as much.
It's also great to be able to cover the whole large pot with fencing or netting or rowcover etc, to protect from frost, birds etc.
When they start producing- you'll get 5 or 6 pints per plant.
The pots I use are from Lowes, Home Depot etc- they are off white (best for not frying the soil, about 20-24 " across, only about 20" deep, but are supported with welded wire fence round cages that I can cover when needed, and that add to the stability of the pot. By the way, the pots come with removeable saucers. I take them off and use them for birdbaths and micro mix growing of lettuce. I drill new holes, about 1/2" all the way around the bottom of the pots about an inch up from the ground. I cut circles of metal screen or landscape fabric to fit into the bottom and up the sides past the holes which keeps out the critters like sow bugs etc.and stops the soil from leaving the pot. I mix in Soilmoist (best price I've found is at LIroots.com), in all my pots. Not cheap, but lasts in the soil for years and years and really helps the pot watering scenario.
Lastly, put the pots in full sun, and make sure they get an inch of water a week, add an extra 1/2 inch a week when they start producing berries.
Don't be put off by the extra work to get going- blueberries are one of the most satisfying long term crops you can have in your garden.Good luck to you.
Rebecca
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