When Should I Prune My Knockout® Roses?


“I live in South Louisiana.  When should I prune my Knockout roses?” Question from Deborah of Saint Amant, Louisiana

Answer: Many growers advocate you that prune shrub roses in late winter or spring before they have leafed out, but some rosarians disagree (see our Black Gold video on pruning hybrid tea roses below.). Either way, I like to prune mine at this time because it’s easier to make cuts on bare branches, and there’s less trouble with pests and diseases. But, Knockouts are everblooming and fast-growing, so you can be pretty carefree about when you prune them, especially down South. (Click here to read more about rose pruning.) Just be sure you use sterile pruning shears or loppers. To keep shears clean and reduce the chance of potentially moving pests or diseases from plant to plant, I dip mine in a 10% bleach solution between roses.

Happy rose pruning!

Jessie Keith

Black GoldHhorticulturist

Is It Too Late to Prune My Roses?

“I live in Kitsap County, Washington (state); is it too late to prune my roses?” Question from Jennifer of Silverdale, Washington

Answer: It’s not too late! Many gardeners advocate pruning roses when they are dormant, usually in late winter, but you can prune them at any time. Whether you have a shrub rose, climber, or hybrid tea, you can make strategic cuts throughout the growing season.

I recommend using very sharp bypass secateurs (pruners) or loppers. The best cross at the cutting junction like scissors. Just be sure to clean your pruning tools between roses to avoid spreading any potential diseases from rose to rose. I recommend cleaning them in a 10% bleach solution with a drop of washing liquid.

Please watch the video below created by Mike Darcy of Portland, Oregon. It highlights rose pruning in your area.

Happy gardening!



How Do I Make My Rose Fuller?

“I had a question about roses. I have a rose bush that blooms by itself every year. I was wondering if there is a way to make it more full or expand it. Thanks!” Question from Lisa of New York, New York

Answer: The best way to encourage a bushier rose is by pruning. Cutting your rose back in later winter to spring will give your rose a fuller, bushier habit. To learn how to prune roses, see the video below.

You can also consider taking cuttings from your rose, if you really like it and want more starts. Overall, roses are very easy to propagate from cuttings, and it’s an easy way to get free roses. Propagating roses is a project best done in summer because roses that have recently bloomed root best. Here’s how:

Rooting Rose Cuttings

Using a sharp knife or pruners, cut stem tips of a rose that has recently bloomed. Cuts should be at a 45-degree angle and the cuttings should be 6 to 8 inches long and have at least three buds along the stem. Cut off the old rose at the top, and remove any leaves from the bottom 3 inches of the cutting. Place the cuttings in cool water.

Prepare a 6″ pot with a mix of one part vermiculite to one part perlite. Wet the mix down, and place a saucer below the pot to catch water. Remove the cuttings from the water and dip them in rooting hormone powder. Dibble out 3″ holes in the mix, and stick at least three cuttings in the pot, being sure to press the mix firmly around them. Keep the cuttings in bright, indirect light in a cool room. Water them just enough to keep the mix moist, not wet.

Rose cuttings can take one to two months to root, sometimes longer. Once they have begun to root, you can upgrade them into a small pot filled with Black Gold All Purpose Mix, and place them in the sun. When they grow further and leaf out well, plant them outdoors!

Happy Rose Growing!

Jessie Keith

Black Gold Horticulturist


Pruning Shrub Roses in Spring

Pruning shrub roses in spring…exactly what does it mean when a rose is called a ‘shrub rose’? In Taylor’s Dictionary for Gardeners a shrub is defined as “A woody plant that is shorter than a tree and usually has several stems that branch from the base”. This definition would certainly fit many rose types, like floribunda (shrub rose crosses between polyantha and hybrid teas roses.), grandiflora (shrub rose crosses between hybrid tea and floribunda roses), rugosa (Rosa rugosa), musk rose (Rosa moschata), or other species shrub roses.

Putting the word ‘shrub’ in front of the word rose has several different connotations. On the Royal Horticulture Society website, they describe shrub roses as flowering just once in the summer and requiring little formal pruning, which is not true for contemporary, ever-blooming shrub roses. As I continued reading their website, I realized they were using the term “shrub rose” to denote what we would call old garden and species roses, (hybrid musk, damask, moss rose, gallica, etc.).

Modern Shrub Roses

Pink Double Knock Out® is one of several roses in the series. (Image by Jessie Keith)

Most gardeners that I know would refer to a shrub rose as one that is bushy, has smaller flowers, masses of blooms, and requires very little maintenance. These are the roses that, here in Portland, we would see along the freeways with flowers that almost cover the shrub throughout the summer. These roses are also often used in commercial parking lots, and some homeowners use them as a mass planting in the front of their home in the space between the curb and the sidewalk.

One of the most popular of the shrub roses are those in the Knock Out® series, developed by Star Roses®. Introduced in 2000, the original Knock Out® is now the most widely sold rose in the United States. This ever-blooming shrub rose has rosy pink flowers, but new selections have been developed with flowers of pink, white, and yellow. It is a very vigorous shrub and is black spot resistant which has made it a favorite of Pacific Northwest gardeners. In my own garden, I have a grouping of Knock Out® roses and they provide a bright spot of color all summer and I have never seen a sign of black spot.

Peach Drift® is one of many shrub roses in the Meilland group of roses. (Images by Jessie Keith)

These are not the only shrub roses on the market, though. Many more, featuring more refined blooms are available through vendors, such as David Austin English Roses. Many of these choice shrub roses are award-winning and selected for disease resistance as well as their voluptuous blooms with great fragrance.

Another recommended group are the popular French Meilland® landscape roses, which are available as a groundcover, bush, or larger shrub roses and feature numerous flowers all season long. They are available in lots of colors and are also markedly disease resistant and low maintenance.

Pruning Shrub Roses

These hard-pruned Knock Out® shrub roses will look full and flowered by summer.

Before doing any rose pruning you’ll need sharp pruning shears or loppers and a pair of thick rose gloves with gauntlet cuffs that resist thorns. I also think it is a good idea to wear safety glasses. The months of February or March are ideal for pruning shrub roses. It is easier to make cuts when the foliage is absent and pests and diseases are yet to be a problem.

When pruning shrub roses, I go back to the Royal Horticulture Society and their web article about shrub-rose pruning where they suggest “little formal pruning.” This is largely because older shrub rose varieties bloom on old wood, but newer shrub roses bloom on new wood, and seasonal pruning can keep their height in check while helping them look tidier.

Thin out smaller branches to open up the bush to more light and air circulation.

When you think of pruning Knock Outs®, these are the freeway roses that maintenance crews prune with power hedge shears! While I would not suggest that sort of extreme pruning for a homeowner, this does give an indication of how receptive they are to rough pruning. Home gardeners will see desired results if they cut shrub roses back just below the final desired height and width; well-established roses will branch out far beyond the cuts you make. Then prune out any dead, diseased, or broken branches, and thin out smaller branches to open up the bush to more light and air circulation. large, old shrubs can be renewal pruned back to 18 inches if they grow far beyond their boundaries.

My Favorite Shrub Rose

Rosa glauca is a species shrub rose with blue-green leaves and single roses. (Image by Rich Baer)

One larger shrub rose that I particularly like, is a species rose called Rosa glauca. This tall-growing shrub reaches 7-8 feet tall in my garden. It is a once-blooming rose with single pink flowers followed by red hips, however, another feature of this rose is the bluish color of the leaves. This is a beautiful background plant; even without flowers, the foliage looks good all summer. Each year I prune my plant to about half its height in March.

Do not be bashful about pruning your shrub roses. They are quite resilient and any cutting mistakes you make in March will probably not be evident by June.

I hope you, the readers of this Black Gold article, also have had an opportunity to see my Black Gold video on pruning hybrid tea roses.

A well-pruned shrub rose looks better all through the season.