Grow low-maintenance, disease-resistant double knockout roses in your yard or garden to add color and enhance the appearance of the landscape. These roses thrive in USDA hardiness zones 5 to 9 and have a prolonged bloom period that begins in June and extends all through the summer, up until the first hard frost. Double knockout rose bushes grow 3 to 4 feet wide and equally tall, with twice the number of petals as the knockout rose variety. Plant this cold-and-drought-tolerant rose variety in groups of three or four to form brightly colored small hedges.
Wear gloves and remove weeds, grass, stones, rocks and plant debris from the selected planting area. Collect in a tarp and dispose. Make sure the planting site has well-drained soil and receives four to six hours of direct sunlight everyday, along with some afternoon shade.
Insert a shovel into the soil to loosen it 10 to 12 inches deep. Add five to six fistfuls of soil amendments, such as organic compost or well-rotted manure to clay or sandy soils, and mix well to ensure they go deep.
Remove the double knockout rose from the nursery container, and view the size of the root-ball. Dig a hole as deep as the size of the root-ball but twice as wide. Plant other double knockout rose plants 3 to 4 feet apart to provide ample space to spread.
Separate container-bound roots gently before lowering the knockout rose transplant in the hole. Make sure it is at the same depth as it was in the container. Back fill with soil to cover the roots, and press down to remove pockets of air.
Pour water over the soil from a watering can. Spread an even layer of organic mulch over the soil to prevent weeds from growing there.
Water the double knockout roses frequently so the soil is moist at all times. Always water at soil level instead of overhead to prevent wetting the foliage, as it makes the plant susceptible to diseases such as powdery mildew.
Feed the plants an organic rose fertilizer every month. Follow manufacturers instructions for directions and precautions.