I was told to feed twice in the spring with a weak fertilizer. Cottonseed meal is supposed to work really well if you want to use a more natural fertilizer.
I have 16 blue berries in 1/2 wine barrels. This is their second year and they are doing great. Drainage and soil Ph is a problem for me as well as oakroot fungus. So growing blueberries in pots works for me the best.
I copied this from a guide to growing blueberries in containers:
Potting mix:
1/3 Pathway bark (1/4 inch)
1/3 Peat Moss (coarse, if you can find it)
1/3 Leaf Mold or Forest Humus based potting soil.
Mix together and add 2 tablespoons of Soil Sulfur.
This will get your container Blueberry off to a great start. Then, in then spring, use a fertilizer high in nitrogen (sulfate or urea) and minor nutrients. The Nitrogen must not be from Nitrate!
This can be deadly to blueberries (don't find out the hard way!).
http://www.davewilson.com/homegrown/promotion/blueberries.html
I just picked up 4 new blueberries to add to my collection.
Chandler
Darrow
Blueray
Pink lemonade- New with pink berries.
Here is a picture showing some of my blueberries in 1/2 wine barrels (on the right of the picture). They are loaded with berries this spring.