Blackberry flavor varies a little bit with the season. If we have cool, dry, sunny weather, you’re going to get really sweet blackberries. If we have cloudy, wet, rainy, hot weather, they’re going to be more tart. This spring has been beautiful but quite variable.

The flavor varies with the variety of the plant also. Some people say the thorny ones are the sweetest but I have got plenty of tart berries while giving blood at the berry patch.

Get your soil tested and make sure you don't have significant deficiencies or excesses. If you stay with an organic program, which should include lots of compost, your soil will come around.

If all else fails, try some stevia which is a natural sweetener from a plant.

Tony M