Hi Pete, I have knockout roses that haven’t bloomed this year, they are two years old. I bought four more from your garden center this year, they bloomed initially in June then nothing. I fertilized when I planted them, then used Miracle Gro two weeks ago. Advice? Thanks!
Feed them in the spring with Flower-tone or Rose-tone as soon as the ground thaws. Once it warms up and they start to grow, feed them every two weeks with Jack’s Blossom Booster. Roses are heavy feeders. Miracle is too high in nitrogen and will promoted leaf growth at the expense of flowering. Miracle-Gro ain’t what it used to be before Scott’s took over. Blossom Booster has more phosphorus for more flowers. Never spray roses with water or food…water the soil below the plant to feed the roots while keeping the leaves and flowers dry, warm and growing as quickly as possible. Cut away spent flowers as soon as they finish…energy spent growing seeds will then be re-directed into growing more flowers. Stop feeding in mid September to let the rose wind down and go dormant without excess stimulation.