Can I Give Fertilizer to My Knockout Roses That Are Not Doing Well?

Site and Space

• Keep Knock Out roses in the outdoor garden down to U.S. Department of Agriculture hardiness zone 5. In colder zones, move them indoors in winter to protect them. Knock Out Roses need full sunshine, quick drainage, good air circulation and adequate space to grow and thrive. If your roses don't have these conditions, move them to appropriate sites and give them each at least 2 to 3 feet of space for growing.

Soil and Nutrition

• All rosebushes require rich, acidic and crumbly soil to thrive. If your Knock Out Roses sit in tight or poor soil, they'll grow sparse and refuse to bloom. Mix 3 inches of organic compost into the top 4 inches of soil around each bush, and repeat once a month. Compost gently increases long-term nutrition, loosens soil for growth and helps soil maintain moisture between waterings. It won't burn or damage rose roots and is safe for consistent and early use.

Fertilizer and Mulch

• Roses are heavy feeders and enjoy frequent feedings. Give your roses granular rose-specific fertilizer to help them recover, but do so carefully. Follow manufacturer recommendations in regard to quantity, and sprinkle the fertilizer in a 12-inch circle around the base of each bush. Don't get the fertilizer against the trunks, as it will burn them. Mix the fertilizer into the top 2 to 3 inches of soil, then water the soil to dissolve the fertilizer.

  Put 2 inches of organic mulch over the soil in your 12-inch circle after you've amended and fertilized. The mulch keeps the soil moist and warm for the roses, and discourages weed growth. It will also add nutrition to the soil as it breaks down.

Watering and Pruning

• Water Knock Out roses consistently to maintain soil moisture. If your watering schedule is inconsistent or light, switch to one or two waterings each week. Give the roses 2 inches of water at each watering to thoroughly soak the soil around the roots.

  Prune off diseased, dead or broken foliage. The damaged foliage saps the bush's energy and restricts new growth. Eliminate the foliage now to help the bush conserve its resources and promote healing.