After careful planting, cultivation and harvesting, it is unfortunate to bite in to a juicy blackberry and discover a bitter or sour taste. There are several reasons this can happen -- old bushes, early picking or inadequate watering. Learn how to prevent this and even what to do if you have a basket full of sour blackberries.
Even when your berries are dark in color, they may not yet be ripe for picking. If your berries still look shiny, wait until they are dull and a little softer before picking. This will ensure the berries will be at their peak of sweetness.
If you don't know the age of your blackberry bushes -- if they were just in your yard when you moved -- it may be that they are past their prime. At this point, there is nothing to do to change it, it is time for new bushes. Bushes will often produce for 15 to 20 years.
Blackberry bushes need a deep and consistent watering to produce the best fruit. They need about 1 to 2 inches of water a week between May and October. If you are under-watering (or even over-watering) your plants, it could lead to sour or bitter fruit production.
What to Do?
If you have a basket full of berries that turn out to be sour, don't despair. Eating them out of hand might not be an option, but you can use them to make jam or even pies or cobblers with enough added sugar and salt, which helps take away the bitter taste.