The 'Double Knockout Rose' is drought and cold tolerant as well as disease and insect resistant. It can be grown in U.S. Department of Agriculture cold hardiness zones 4 through 9. The 'Double Knockout Rose' produces cherry red double flowers, meaning the roses have more than one row of petals on each flower. The plant grows to 4 feet tall and wide if not pruned. It can be pruned after each bloom period to maintain a compact shape, but it performs best if allowed to grow naturally. The 'Double Knockout Rose' bush was introduced by Conard-Pyle nursery.
Choose a location to plant your 'Double Knockout Rose' with at least six hours of sun each day, which is considered full sun. Although mildew and black spot resistant, the plant still needs good air circulation around the foliage to eliminate mildew problems. The area where the Double Knockout rose is planted should have good drainage.
Clear the planting area of weeds and loosen the soil to a depth of 1 foot, adding a few shovelfuls of compost where the bush will be planted. If you are planting more than one plant and want a continuous hedge, space plants 3 feet apart. Continue to add compost to the planting area and work the compost into the top 1 foot of soil.
Dig the hole for the 'Double Knockout Rose' deep enough so the bush is planted the same depth as it was planted in the container. The hole should be about twice as wide as the planting container to allow the roots to establish easily.
Remove the 'Double Knockout Rose' from its container and place in the prepared planting hole. When adding the dirt back into the planting hole add a generous amount of water so the soil forms a good seal around the roots, eliminating any air pockets.
Spread a 1-inch layer of mulch around the roots base of the plant. Do not fertilize for the first six weeks after planting so new roots can become established. After that, according to My Rose Guide, the 'Double Knockout Rose' use slow-release organic fertilizer that is slightly acidic once a year. Use all fertilizers as instructed on the fertilizer's label. Do not over fertilize or the bush will produce more leaves at the expense of blooms.