How to Trim Knockout Roses
- 1). Use a pair of sharp pruning shears to trim the Knockout rose trees in the summer to keep their shape. Cut back the outward growth one-third. Even out the side limbs. If some branches are growing faster than others, trim those back.
- 2). During the pruning season of spring, it's safe to cut the Knockout rose tree down to 12-inches tall. The Knockouts are okay if left alone--their growth will not over dominate--but if your yard size is limited, cut them back.
- 3). Remove faded and dying blooms, with a pair of garden snips, to encourage new growth. Although, the Knockout rose trees are considered self cleaning and do not require dead-heading.
- 4). Do not trim your Knockout roses in the fall to prevent damaging the plant and hindering new growth. Always trim the trees before new growth emerges but after winter frost.
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