You may be picking too soon - the berries I picked off my rabbiteye bushes 2-3 weeks ago were pretty tart - but they usually sweeten up if you leave 'em sitting out at room temperature for a few days. I've picked a 2-3 gallons in the past two days - most of these berries probably have been fully 'blue' for a week, some are actually starting to shrivel(we've had daytime temps into the 90s and no rain), but most are quite sweet.

You don't mention which variety you grow. I recommend to all who are inclined to plant blueberries to try some of the berries off that variety before you purchase and plant it. I grow appox. 20 different varieties and like apples they taste different from one another. Some varieties are tart but produce wonderfully, others are sweet and flavorful but produce poorly.

It occurs to me that a second problem is listed in your saying "planted a few months ago". It could very well be that you have more berries on the bush than it can support. Another good reason to remove blooms the first few years is that the roots can't support a whole lot of fruit anyway.

gmason has the most likely cause, over setting. This is especially bad on young plants because it stunts the growth. Next year make sure there are a lot more leaves than fruit. You don't need to remove all the fruit next yr, just make sure there aren't too many. My potted bushes tend to over produce even though I prune heavily after harvest and lightly in the spring.

This yr I had the best bb I've ever eaten by leaving Southmoon on the bush at least 6 wks after they turned blue. Very sweet with a unique tangy flavor.

The Fruitnut

I don't know what variety of blueberry the plant is. It is over flowing with berries though. 80% berries and 20% leaves. Should I cut the bush to the ground at the end of the season or should I do some trimming now? What's my best course of action?

No. Leave the foliage alone. What you want to remove is the fruit/blooms. As Fruitnut says you need to let the plant grow for a few years. Even then some varieties will overset fruit like fruit trees do and will be helped by some selective thinning.

lumpy:

Pruning is an option on mature plants. By pruning a big plant you are trying to make it more vegetative and less fruitful. On a young plant pruning is a poor option. You need to retain all the leaves and remove most of the fruit so as to reverse that ratio. Sorry I gave you the impression that pruning is a good option for you.

Of all the fruit I've grown, blueberries are the most prone to overbear as a young plant. Many fruit overbear as a mature plant. But bb are the winner as a small plant.

The Fruitnut

I'm surprised at the time some of you leave the berries on the bush after they turn blue. I will try that next year to see if the flavor improves. Thanks for the comment.

As regards pruning, my dad planted my bushes years ago and over time they have gotten wild and large, to the point they are difficult to harvest. Some are so old they have begun to die off. Can I/should I prune them back to a managable height and size? If I do so, what should be removed: Old branches, young branches, volunteers?

Thanks

Here is a guide.

Here is a link that might be useful: Oregon state blueberry