How to Grow Double Knock Out Roses

Double Knock Out rose image by H.B. Dean


The Double Knock Out rose is a popular choice for beginning and veteran gardeners alike. The double version of the original Knock Out grows 3 to 4 feet tall and 3 to 4 feet wide. The double flowers--available in pink, red, coral and yellow--bloom from spring until the first frost. Once established in the garden, the Double Knock Out rose is disease-resistant, drought-tolerant and requires little maintenance.

Preparing and Planting

Step 1

Prepare the garden for Double Knock Out roses a month before planting. Like all roses, they need at least six hours of full sunlight daily. They thrive in rich, well-drained soil that has a pH of 5.8 to 6.8. Test the soil a month before planting and amend it with sulfur or lime if necessary. The University of California Extension has a chart explaining how to amend different types of soil.

Step 2

Plant the rose after all threat of frost has passed. Dig a hole 2 feet deep and 2 feet wide, placing the soil on a tarp or in a wheelbarrow. Estimate the amount of soil removed and add equal amounts of mulch, peat moss and potting soil to create a planting mix. Fill the hole half full with the planting mix, add water to the top of the hole and mix with a shovel. The water/planting mix should be thick like melted ice cream.

Step 3

Place the Double Knock Out rose in the middle of the water/planting mix. Hold it so the bud union--the swelling where the rose's roots and canes meet--is directly above the hole. Add more planting mix until the hole is filled and the mix is firm.

Step 4

Spread a 2-inch layer of mulch under the rose bush. Build a dam with the mulch around the rose, about 1 foot away on all sides. This will hold in the water while the rose is settling into the garden. Cover the bud union with mulch until new growth appears, then gradually remove it.

Rose Care

Step 1

Water the Double Knock Out rose about once a week, depending on rainfall. The rose needs an average of 1 inch of water per week. Do not spray the bush--direct the water toward the roots.

Step 2

Feed the plant with a complete rose food. The method and frequency of application depends on the type of rose food.

Step 3

Weed around the bush, using a tool to remove weeds by their roots. Lawn fabric placed under the mulch reduces the growth of weeds.

Step 4

Prune the Double Knock Out rose in the spring. Cut it about 1/3 to 1/2 of the bush's height. Knock Out roses are self-cleaning, so there is no need to deadhead.

Things You'll Need

  • Shovel
  • Soil testing kit
  • Sulfur or lime
  • Mulch
  • Peat moss
  • Potting soil
  • Time-released rose food
  • Herbicide (optional)
  • Weeding tool
  • Pruning shears (optional)
  • Gardening gloves
  • Lawn fabric (optional)


  • "The Complete Garden Flower Book:" Catie Ziller, Publisher; 2001

Who Can Help

  • University of California Extension: "Changing pH in Soil"
  • Conard-Pyle: The Knock Out Family of Roses
Keywords: growing roses, Double Knock Out, rose

About this Author

After attending Hardin Simmons University, Kay Dean finished her formal education with the Institute of Children's Literature. Since 1995, Dean has written for such publications as "PB&J," Disney’s "Family Fun," "ParentLife," "Living With Teenagers" and Thomas Nelson’s NY Times bestselling "Resolve." An avid gardener for 25 years, her experience includes organic food gardening, ornamental plants, shrubs and trees, with a special love for roses.

Photo by: H.B. Dean