what is best fertilizer to use on blackberries
Fertilize blackberry bushes in the early spring just as they begin to put forth new growth. Use 1 pound of 20-20-20 granular fertilizer for every 25 feet of row, broadcasting it evenly around the base of your shrubs. If you use 10-10-10 fertilizer, apply 2 pounds for every 25 feet of row. Feed blackberry bushes again when they are blooming in midsummer. Do this only if your bushes are not thriving. Apply 1/4 pound of a 34-0-0 fertilizer, also called ammonium nitrate, for every 25 feet of row.