The Knock Out rose family (sometimes also called Knockout roses, although the trademarked name uses two words) is one of the toughest around, with easy care requirements and high disease resistance. These qualities make it a favorite of many home gardeners who want to have lovely roses without the intense maintenance routines that many other roses are notorious for.
Roses have long had a (relatively well-deserved) reputation as being high-maintenance flowers. The work paid off, of course, when your rose bushes bloomed and you could smell that lovely rose fragrance. However, that high maintenance also made roses not so welcome in many gardens that weren’t cared for by professional gardeners. The Knock Out line was created specifically to let people have roses that were much easier to maintain.
As simple as their care may be, however, Knock Out roses do require a minimum level of effort. Proper planting, watering, and monitoring for diseases will make these roses flourish in most yards. If you can dig a hole and pinch off a leaf, you can care for Knock Out roses.
If you’ve never grown roses because you thought they were “advanced level gardening,” then keep reading to learn more about Knock Out roses. You may decide that roses are for your garden, after all!
The Story Behind the Knock Out Line
Knock Out roses were created in 1989 by Will Radler (his name is variously listed as Will or Bill, depending on the source), a rosarian in Milwaukee. A rosarian is someone who breeds rose cultivars. He was just a teen at the time and wanted to make rose care easier for the average gardener. Over the next decade, he continued to refine the rose line, and in 1997, the first Knock Out rose was named a winning selection by the All America Rose Selections organization. Soon after that, in 2000, the Knock Out rose became available commercially.
Over the years, more Knock Out rose varieties have been created. These roses are now available with single or double blooms, in several different colors. New selections continue to be introduced. The only real restrictions on growing these roses are that your garden generally has to be in USDA plant hardiness zone 5 or warmer and you have to provide basic plant care.
Knock Out Rose Characteristics
The typical Knock Out rose bush grows to about 3 feet tall by 3 feet wide — occasionally it can grow to 4 feet. Varieties include a mini rose version, double blooms, single blooms, and at least seven different color options.
The flowers appear in loose clusters with fairly open blooms, and the plants, as compact as they are, can be used for hedges and borders in addition to being in the garden spotlight themselves. They are fantastic additions to gardens in hotter areas as they’re heat-tolerant.
After the blossoms fade, bright rose hips appear for visual interest in the fall.
A Note About Disease and Pests
One of the Knock Out line’s defining characteristics is how resistant it is to the usual rose diseases. It’s not a disease-proof line; you still have to monitor for issues like powdery mildew and rose rosette. Keeping your roses healthy is the best defense against diseases.
This article will let you know how to identify pests and signs of them attacking your roses, as well as the steps for removing them.
Another Knock Out Benefit: It’s Self-Cleaning
Knock Out roses have a unique feature: They’re “self-cleaning.” No deadheading is required, unless you don’t like seeing rose hips. In that case, just pinch off spent blooms. Petals fall away once they wither, so the only post-bloom work you need to do is tidying up beds and removing fallen flowers.
Yearly pruning is necessary to keep the plants compact. For most Knock Out roses, pruning the canes back once in late winter or early spring to 1 foot high – prune when new growth appears – helps the plant maintain its shape. In colder zones with severe winters, prune canes back to the ground about 3 inches high just before winter. For petite or mini Knock Out roses, prune back to 4-6 inches high in the late winter/early spring.
While pruning, check the remaining canes for damage, such as from winter frost. Trim away those damaged canes.
How Long Do Knockout Roses Live?
Like other rose bushes, Knock Out roses are perennials. The bushes will bloom year after year as long as they receive good care. The flowers may last only a few days, but they bloom again and again during the season — you can have anywhere from five to seven blooming cycles. If you plant more than one Knock Out rose bush, you can see a lot of flowers daily in your yard.
As for the life of the bush itself, the average rose lives for about 15 years.
When and How to Plant Knockout Roses
Find a sunny spot since Knock Out roses need six to eight hours of sun per day. Dig a hole slightly wider and deeper than the container the roses came in.
The soil at the bottom of the hole should be loose — use your shovel to break up the layer of soil. Remove the roses carefully from the container when planting them and loosen the root ball gently. You want to help the roots to start extending and growing but you don’t want to damage them.
Plant the rose so that the bud union is slightly below the soil line. Once the hole is filled in and the plant settles, this will be 1-2 inches below the soil surface. To know what the bud union looks like, watch this video for a quick explanation.
Water deeply and spread mulch after planting. Water every other day until you see new growth starting and then switch to weekly watering.
Plant Knock Out roses in late winter or early spring, after frosts are done.
If you need to transplant your Knockout roses, it’s is simple, but requires the right timing. Wait until early spring (before the growing really starts) and carefully dig up and move the rose bush. If the rose wilts, it’s likely transplant shock — water well and monitor it. It should recover in a few days.
Do You Need to Fertilize Knock Out Roses?
You don’t need to fertilize these roses, which is another reason they’re so easy to grow. If you want to fertilize them, or they’re planted in poor soil, wait until the second year the roses are in your garden. Use a fertilizer formulated for roses and follow the directions carefully.
There are some rose fertilizing Do’s and Don’ts to be aware of:
- Fertilize only after the first cycle of blooms is finished, which will be sometime in spring.
- Be aware that you must water the soil first. If you don’t, the fertilizer could actually burn the plant, potentially killing it.
- Avoid fertilizing the plant in late summer to prevent new growth that will be damaged by frost in the fall.
Varieties of Knock Out Roses
The family of Knock Out roses continues to grow as breeders create new varieties. The original Knock Out rose, ‘Radrazz’, offers hot pink to cherry red double blooms. This is the rose that started it all, and it remains a winner for those who want low-maintenance flowers.
The following are varieties of Knock Out roses to look for:
Double Knock Out, or ‘Radtko’, is a cherry red, full blossom that is one of the varieties that looks more like a traditional rose. It has a sweet fragrance and can be grown up to zone 11.
Pink Knock Out, or ‘Radcon’, is – as you can guess from the name – a lovely pink color. These have open double blossoms.
Pink Double Knock Out, or ‘Radtkopink’, has pink, fluffy blossoms that are very, very drought-tolerant. This is a great flower for drier areas.
Blushing Knock Out, or ‘Radyod’, has many light pink blooms. The petal colors themselves vary a bit, with lighter and darker patches that are still subtle.
Rainbow Knock Out (‘Radcor’) is a real knockout itself. Coral pink petals turn golden yellow as they head toward the very center of each flower.
Sunny Knock Out (‘Radsunny’) is a yellow variety that has yellow centers and creamy outer edges. It has a citrusy fragrance.
Coral Knock Out (‘Radral’) is an orange flower that has a more intense orange color in hotter climates. It’s also one of the taller varieties, with bushes reaching up to 4 1/2 feet.
Peachy Knock Out (‘Radgor’) has light pink petals with yellow centers. The colors will be brighter in cooler seasons.
White Knock Out (‘Radwhite’) has simple white blossoms. The flowers are bright and cheery.
Petite Knock Out (‘Meibenbino’) is a miniature plant that grows to 18 inches tall. You can train this into a tree shape if you want.
Where To Buy Knock Out Roses
Knock Out roses can be purchased at local nurseries or garden centers (including ones at big box home improvement stores). You can also buy them from online retailers, such as Nature Hills Nursery.
Wrapping Up Knock Out Roses
If you’ve never grown roses before, Knock Out roses are a great place to start. Low-maintenance, fairly resistant to disease, and blooms that just keep coming and coming — what’s not to love about these roses? Once you get the hang of growing a couple of these, you might just find your collection of roses taking up more space in your garden each year!
Are there Knock Out roses putting on a show in your garden each spring and summer? If so, we’d love to hear about your experiences in the comments section below! To read about other kinds of roses, click here for our roses blog posts.