How to Fertilize Knockout Roses


The Knock Out family of shrub roses were bred by the Conrad Pyle Co. to be disease resistant, low maintenance and tolerant of weather extremes most rose plants would not be. They do, however, still benefit from regular applications of rose fertilizer to boost the health of the plants, compensate for deficiencies in the planting soil and boost bloom capacity.

Step 1

Clear the soil below your Knock Out rose shrubs of any fallen leaves, petals, cane cuttings, weeds and debris so that you have a clean soil surface, free from disease breeding materials, to apply the fertilizer over.

Step 2

Choose a good quality slow release synthetic fertilizer or an organic rose fertilizer with a guaranteed analysis of 5-10-5, 4-8-4, or 4-12-4 or a similar ratio of macro-nutrients. Look for fish emulsion, blood meal, bone meal and greensand in organic formulations.

Step 3

Scatter the label recommended dose of organic or slow release rose fertilizer around the entire root zone staring a few inches out from the mail trunk and extending to past the drip line of the shrub. Nestle the fertilizer into the top inch or two of soil but do not dig it in as you may disturb the more shallow roots. Repeat applications throughout the year from spring through early fall as recommended for your product and climate.

Step 4

Boost the soil acidity around your Knock Out roses to withing their preferred range of 5.5 and 6.5, if needed. Make a single annual application of ground limestone in the spring or summer. Apply two Tablespoons of the soil amendment for each shrub, each year. Cast the amendment around the root zone of the rose keeping clear of the trunk and extending to the drip line. Nestle the lime into the top inch or two of soil and water in well until the soil is drenched several inches down.

Things You'll Need

  • Slow release synthetic or organic rose fertilizer
  • Ground lime soil amendment/fertilizer
  • Garden gloves
  • Water


  • Conrad Pyle Co.: Knock Out Roses
  • University of Missouri: Rose Care After Planting
Keywords: Knockout Rose shrubs, fertilizing shrub roses, organic rose food

About this Author

An omni-curious communications professional, Dena Kane has more than 17 years of experience writing and editing content for online publications, corporate communications, business clients, industry journals, as well as film and broadcast media. Kane studied political science at the University of California, San Diego.