A gardener wrote in recently:
“I have thornless blackberries bushes, but every year the berries are sour. What can i do to sweeten them up?”
I don’t have personal experience with thornless berries, but in my research I found two common answers to this question.
1) The berry bushes may be old and apparently there’s nothing to be done about it. Time to get new berries.
2) It’s important to wait to harvest the berries until they are no longer shiny. They will have passed from the dark black, shiny stage into a duller black stage and should come right off the vine easily. They will be much softer at this stage as well.
The second answer was most common in my search. As far as soil goes, here is an excerpt from Paul Vossen on Growing Blackberries in California:
“Blackberries do best in well-drained sandy or loamy soils with a pH between 5.5 and 6.5. A good supply of organic matter in the soil improves aeration and drainage and increases water-holding capacity. You may apply organic matter during the summer or fall before you plant. … If you use manure, compost or another source of organic fertilizer, apply it in the late fall or early winter. Apply approximately 50 pounds …per 100 feet of row. If the plant lacks vigor, apply an additional 1 pound of ammonium nitrate per 100 feet of row at bloom or midsummer, just prior to an irrigation. ”
Regarding irrigation, he says:
“Blackberries require approximately 1 to 2 inches of water per week from mid-May through October. It is best to keep the plants moist at all times without soaking and rotting the roots. Blackberries do better if the entire row is kept moist.”
Hopefully this information will help you with your blackberry problems. Keep us posted on your next harvest.
Thanks for writing in!
Does anyone out there have another suggestion for this issue? Let us know!
According to our extension service, sour blackberries are caused when there is a slow ripening season. This is caused by dry or colder than usual weather.
Ah, yes! Thank you Sherry for the bonus info.
Much to my misfortune, we do not yet have blackberries in our garden. Someday when we have the rest of the landscaping figured out, I’ll find a place to tuck them in. Sorry to hear your berries are sour. Did you try the solutions mentioned in the blog post?
I will try what you’ve said
Thankyou.
I would like to know how Christy’s berries did this season (2009). Our thornless berries are beautiful – big, full, and dark but sour as a lemon! Did you find a remedy? Thanks!