February 2018

How to prune Knock Outs and other tips on care of ‘everyday’ roses

Flower Carpet Coral rose. Photo courtesy Flower Carpet Roses

There still seems to be a lot of confusion about how to care for some of the newer roses in our landscapes.

Knock Out, Drift, Flower Carpet, Oso Easy, Storybook, Simplicity and several in the Easy Elegance series are shrub roses. Sometimes called landscape or ground cover roses, these are generally low maintenance plants, which are disease and insect resistant. The most questions are about pruning these roses.

“My Knock Out bushes have become quite large since planting about six years ago. How low should I trim them back? When is the right time to do this?,” writes reader G.R.

J.O. writes “I have two rose bushes which I have let get too tall and leggy.”

Most of the shrub roses can be cut back about as far as you would like. That can be one-third, one-half or down to about 10 or 12 inches from the ground. Pruning can be done to shape up the plant or to reduce its size. Always use sharp pruning tools.

“I suggest you prune when the forsythia start to bloom, which is usually around March or April,” writes Paul Zimmerman in Everyday Roses: How to Grow Knock Out and Other Easy-Care Garden Roses, published in February (Taunton Press, $22.95, paperback).

Start with removing any dead wood or crossed branches. Always cut back to healthy growth. Leaving spindly branches at the top means the flowering will not be a great, wrote Zimmerman, coordinator of the Biltmore International Rose Trials and an American Rose Society Certified Consulting Rosarian.

Zimmerman recommends applying an organic, time-release fertilizer in spring and late summer. Although roses do not need a lot of water, they do need a good deep soaking every week to 10 days. In my experience, irregular watering will disrupt the flowering process for a few weeks. Shrub roses generally flower for six weeks, rest for a couple of weeks, then start blooming again.


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