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How to Fertilize Knock Out Roses

By Jay Golberg ; Updated September 21, 2017

Knockout Roses are part of a family of rose bushes developed by Conard-Pyle nurseries. These tough rose bushes survive adverse climate conditions and resist disease and insects fatal to many other rose varieties. Because of their dependability, Knockout Roses are very popular plants for landscaping. Knockout Roses grow 3 to 5 feet tall and wide and can be used as a hedge or grown as a single specimen plant. They have a flush of blooms in the spring followed by sporadic blooms, then another flush of blooms in about six weeks. This pattern repeats itself until freezing temperatures in the fall. Wait to fertilize newly planted Knockout Roses, as these bushes are putting out tender new roots that are susceptible to damage from the nitrogen content of fertilizer.

Fertilize Knockout Roses after the plants are established and have produced one bloom cycle.

Water the plants well before fertilizing. Set a water hose with a trickle of water at the base of the plant for 30 minutes.

Remove or pull back any mulch around the base of the Knockout Rose bushes. Add a timed-release rose fertilizer around the base of the plant. Read the fertilizer container label and apply the fertilizer only as directed. Over-using fertilizer may damage the plant or cause the plant to produce more green growth than blooms. Never use any fertilizer on Knockout Roses that is not listed specifically for roses because it can damage the root system of the plant.

Replace or add a 1-inch layer of mulch around the base of the Knockout Rose bush to conserve moisture and control weeds.


Things You Will Need

  • Slow-release rose fertilizer
  • Mulch

About the Author


Jay Golberg is a certified Texas nursery professional and professional project manager. He has 30 years of business and farming experience and holds bachelor's degrees in English writing from St. Edward's University and finance from Lamar University.