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!
My BlackBerry bush is about 3 years old. This is the first year I’ve gotten a bumper crop of blackberries I can’t count how many quarts but there’s sour but not real sour. With a little sugar they are edible. There must be something you can put on the soil to make the berry sweet but what is it??? I’m in Michigan
This may sound weird but have you checked your brix levels lately? Brix is the amount of sugars in the fruit. To increase brix levels, I always come back to increasing the soil microbes, which in turn process nutrients, allowing plants to take up the minerals that make fruit sweeter. Compost, compost tea, worm castings. That should help increase brix levels.
I moved to a home outside of Cleveland, and the blackberry bushes were recently planted. They produced a lot of bitter berries. My chickens won’t eat them either. I’m going to try the compost manure suggested, and maybe next year they will sweeten enough to eat.
My second year thornless blackberries are prolific, large and very juicy but still 85% are sour. Not sure why. Well drained, organically grown and fortified with compost and chicken manure at beginning of season and fed twice during growth.
HI Karen, give these solutions listed in the blog post and the comments a try. Keep us posted on how things go.
Just moved to Vernon BC Canada, And my blackberries are also sour. I am also looking for an answer how to make them sweeter. Maybe they are naturally sour just like sour cherries.
Still looking for a solution myself. Third year plants in container. Berries on second year growth. Trimmed first year out last winter. Berries are large, black and soft – juice to the touch. Many falling off the vines now. They are sweeter if picked just after they begin to loose their gloss. But probably 3 in 4 berries picked are sour or slightly sour. So much so I can’t use them for baking or salads. I am interested in knowing if anyone used the soil amendments mentioned and if that sweetened the berries. Mine are also thornless. Are least our scrubjays don’t seem to mind the sourness. They are out there eating them daily 🙂 🙁 Thanks everyone who contributes to this issue. Sacramento, Ca.
My plants are just in there second year of being planted here and they had some berries last year and very nice looking big fruit, but they were extremely sour? HELP PLEASE BEAUTIFUL EXTRA LARGE FULLY FILLED OUT BUT EXTREMELY SOUR BERRIES! HELP THRY WOULD MAKE YOU PUCKER UP LIKE EATING A LEMON!! Help please!!
We have the same problem, our plants are in their 3rd growing season and the fruit is as sour as the Mother In law, no amount of Chocolate will sweeten her up, and I suspect the same but fertilizer with the Blackberries, an old Gardener friend has suggested to throw them out and start over again with an older variety, he suggests that some of these newer models have been played around with too much???
Cheers.
Alan..
Interesting thought. I don’t know enough about breeding blackberries to know whether they occasionally go rogue or not. It’s possible with pretty much every other species, so I wouldn’t be surprised. 3 years is enough time to test out a variety. If it’s not working, I’d agree with your old gardener friend and replace them.
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.
That was not the case with mine, I felt like they ripened pretty much as fast as any that I have seen. They were very large berries and fully developed and juicy. I was so excited to see the size of the berries and just how nice they were to be on a going plant for me. This was their second year planted here. I read somewhere that it was not uncommon for them to be sour their first season to bear, also that lime might possible help to sweeten them up. I have no idea how much lime I would need, this is all new for me. I normally stick to flowers! Thanks for the input.
Here is another angle to take – your brix (sugars) level may be low in your soil. Humic acids can be applied to increase soil brix levels. Many fruits become sweeter when brix levels are increased. Humic acids are readily available in liquid form, and you can find arctic humus in bags online. See if that helps.
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!