One of the things what we struggled with this year is knowing when our blackberries were at their optimum for picking.If you are thinking about planting blackberries, my best advice is to plant the Ouachita variety because you can tell when its berries are ripe because they swell to enormous size that are differentiated from the smaller, unripe berries.
If you are picking other types of berries, it is a bit more challenging.
Obviously, if the berry is red, it's not ripe!
Kim Pierce of the Dallas Morning News wrote a piece on June 4, 2010 that I thought was helpful and gave a few more hints. Here is an excerpt:
"If you're picking blackberries, Cowdrey says, they're ripe when they lose their shine. The color turns dull, and they fall off in your hand. 'If you have to tug at it,' he says, 'it's not really ripe.'"
I think the "tug" advice is dead on.
As to telling when a blackberry is "dull", it takes a lot of practice to tell when a blackberry has lost its shine and is dull. But, once you know what you are looking for, it can be a pretty good indicator.
The taste test is also helpful. In other words, taste a nearby berry to see if the others are also ripe. However, one caveat, this is not foolproof because the berries ripen at different times. Consequently, the one you taste may be ripe, but others nearby may still need a few more days to reach perfection.
Not to worry, Kim Pierce's article notes that you can always add a bit of sugar to your berries to add sweetness.