Few blackberry canes
Several years ago I planted 5 thornless blackberry plants. Last year I noticed that I stopped getting new canes on 2 of them, so I have no blackberries from those 2 plants. This year there is only 1 cane from a third plant and still nothing from the 2. My other 2 plants have about 15 new canes each. I have bent 3 of those canes and planted the tips where I have no new growth. The ph on the two doing well is 6.5. Where there is no growth 5.5-6.0. I use 10-10-10 fertilizer and they are not mulched. Any suggestions?