Blackberries tend to be on the tart side. Most of your customers will know that - maybe just verbally tell the people who have never eaten them before that they are tart.

What kind are they? I find the wild ones to be tarter than the domesticated - at least the ones I buy in stores. My Triple Crowns (planted this year) have just 3 berries on them and they're still green so I haven't tasted them yet.

Berries will be somewhat different each year depending upon how much rain and heat that you get. I believe blackberries are tarter than 'tame' raspberries.

Wild berries are usually more 'intense' or concentrated taste than the tame or domesticated berries, but the wild ones will survive better than the tame ones.

Marla

The wild blackberries are definitely a lot tarter than the wild raspberries (in fact, I believe the wild raspberries are sweeter than the domesticated, but they're softer too so harder to get to market).