I would be very careful fertilizing after August. I fertilized a small fig first of September and it never stopped growing. A late November frost knocked all the leaves off. It put out new growth and got hit with frost again, did this 2 more times and then died. You don't want to push a lot of new growth going into the winter. I don't know if fertilizer would stress it in the heat.

Did your primocanes come out thinner and weaker than last year's florocanes?

Yeah, I wouldn't put fertilizer on this late in the season. It may just push growth that wouldn't harden off properly. Best way to improve growth is to fertilize with ammonium sulfate in the spring, and remove all flowers for that year. It's amazing how much blueberries grow without flowers.

Capoman you must have blueberries on the brain.

SgtKarl

Fertilize your blackberry plants today cooler temp coming down and so is growth coming back. Remember Blackberry plant fall in class as Heavy Feeder you grow larger root system if any fertilizer left in soil over winter spring brake out have larger flowers and larger leave this make more sugar and sweeter berry. Spring at 5% bloom is next fertilization that 4 days after you see first bloom on all plants then again at 100% bloom this make berries bigger and give great start on new canes after harvest another application I just gave 4 applications in year for Blackberries this take care heavy feeding of plants. I put out chicken mature 3 tons to acre in December and 4 application during year 10-10-10 on sandy land.