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Double Knockout Roses

The popularity of roses in household gardens started to wane in the late ’90s. Roses were considered finicky and highly susceptible to disease. Then Double Knockout roses were introduced and they’ve been some of America’s favorite roses ever since.

The Double Knock Out Rose is also known by the name Rosa Radtko in the rose community. The Knockout rose family is great for new and well-established gardeners.

We will discuss everything you need to know about growing and decorating with Double Knock Out roses.

Closeup of a single dark pink rose bloom.

History of The Double Knock Out Roses

The Knockout rose is the first variety of a species of rose created by rose specialist William Radler and introduced to the world in 1989.

Radler’s goal was to create a rose that could last. Radler noticed a decrease in the popularity of the rose plant. He created the Knockout rose with one goal in mind — disease resistance. Radler put the Knockout rose to the test by introducing many rose diseases to the plants to make sure they could thrive. This allows growers of all skill levels to enjoy roses in their gardens again.

The Knockout rose was created by mixing the Floribunda with the Razzle and Carefree Beauty — it produced a single tier of petals. The plant blooms with 5 petals per flower. The Double Knockout is a variation of the original Knockout rose. The Double Knockout is beloved by many for the fuller flowers it produces. The Double Knockout rose has two tiers of petals creating a fuller look to the bloom.

A pink Double Knockout rose shrub.

Characteristics of The Double Knockout Rose

The Double Knockout is a woody shrub that grows between 2 and 4 feet tall and 3 to 4 feet wide. The shrub has a continuous bloom and will flower for most of the year. It is the thorniest rose shrub available — use gloves when working with the plant.

The unique characteristics of the Double Knockout rose are its bright cherry red color, continuous full blooms, and the deep purplish-green foliage it grows. The Double Knockout is not well known for being a strongly scented flower. Some people say there is no scent while others say the scent is more of a delicately sweet and fruity scent.

Double Knockout Roses are considered disease resistant, drought-resistant, and pest resistant.

Closeup of single dark pink rose bloom.

Double Knockout Roses in your Garden

Caring for a Double Knockout Rose shrub is easier than any other type of rose in the rose family. There are still some important care tips to keep in mind when caring for Double Knockout Roses.

Watering Your Double Knockout Roses

Water is the most important in the first year of growth. Water the shrub 2 to 3 times a week making sure the top inch of soil is soaked. You will need to water more during the summer.

Sun

Double Knockout Roses prefer full sun for at least 6 hours a day. While they can grow in shade, you’ll see fewer blooms.

Closeup of red Double Knockout rose bloom.

Soil

All varieties of the Knockout rose family prefers well-draining soil. Use a mulch or bark mix at the base of the shrub to help keep the soil moist underneath.

Pruning Double Knockout Roses

You do not need to prune Double Knockout roses. The flowers will naturally die and fall off on their own leaving space for new flowers to bloom.

If you are a fan of keeping your garden looking fresh and beautiful you can prune off the dead or dying blooms for your own satisfaction. It won’t hurt the shrub. You can also prune dead or dying branches to increase the thickness of your shrub greenery.

Pruning Tips

  • Use pruning shears
  • Prune less not more
  • Prune dead or crossing branches to keep the shrub looking full
  • If you’re going to prune a branch don’t leave a stub, cut the whole branch as the plant doesn’t grow back from the stub

If you are trimming for fresh-cut flowers you should cut the stem to the base of where it comes out of the cross branch. Leaving the nubs or half branches will decrease blooms. Trimming off intersections can improve the blooms on your shrub.

Closeup of pink Double Knockout rose blooms.

Planting Instructions

There are two ways to plant Knockout Roses. You can start them from seeds or purchase plants in nursery pots.

Planting From a Seed (a Rose Hip)

  1. Plant during winter in an area with no frost, plant in spring if your area commonly gets frost
  2. Pick a nursery pot with good drainage
  3. Use commercial potting mix at a one-inch depth
  4. Place the seed in the center of the pot just under the top layer of soil
  5. Water the nursery pot fully
  6. Place the nursery pot outside in the direct sun

Your new plant should sprout in about 6 weeks. Once it has sprouted you can move your rose shrub into its new home when it reaches a few inches tall.

The great thing about Knockout Roses is that you will likely see blooms within the first year.

Planting from a bush

  1. Plant in early spring
  2. Pick a place with good air circulation, 6 hours of direct sun, and well-draining soil
  3. Dig a hole just deep enough for the root ball to be covered
  4. Check your soil pH it should be between 6 and 6.5
  5. Add lime if your soil pH is low and sulfur if your soil pH is high
  6. Loosen the roots on the root ball
  7. Place the plant in the hole and fill the hole with dirt
  8. Water your shrub deeply when it is fully planted
  9. Add mulch around the plant to keep moisture in and weeds out

Transplanting Double Knockout Roses

The best time to move your plant is in late winter if your area is not likely to frost, or early spring if you often get frost.

To transplant your Double Knockout Roses:

  1. Dig the new hole first make it double the height and width of the expected root ball
  2. Dig up the rose shrub using a sharp shovel, make sure to get as much root as possible by digging out wide
  3. Allow some dirt to fall from the roots but try to keep the roots intact with the dirt that comes with it
  4. Use a burlap sack to move your rose shrub if it is large
  5. Break up the root system when you are above the new hole
  6. Cover the newly placed root system with commercial-grade potting soil

You can now water and prune your newly planted shrub. Double-check that all dead pieces of your shrub are pruned once you have finished re-planting. This helps the plant focus on new growth and not trying to fix itself.

Water 2 to 3 times a week and watch it grow!

Varieties of The Double Knockout Roses

The Double Knockout Rose comes from the original rose variation called the Knockout rose. Double Knockouts are two-tier blooms in red or pink colors.

Closeup of single red rose bloom.

Double Knockout Roses in a Bouquet

Taking fresh cuts from your Double Knockout rose shrub will help improve its blooms. It is a woody shrub and as long as you take clippings without leaving numbs your plant will try and fill in the spots removed with more branches.

The Knockout family of roses is a shrub-based rose and because of this, they have a short vase life.

They are best used in small vases or mixed wildflower arrangements. The stem of the flower is short, and does not have the long sturdy stem of the common long-stemmed red roses used in floral arrangements.

Close of cluster of pink Double Knockout rose blooms.

Frequently Asked Questions About Double Knockout Roses

How Tall do Double Knockout Roses Get?

Double Knockout Roses can reach a height of 6 feet. Most Double Knockout shrubs average between 3 and 4 feet tall.

Do Double Knockout Roses Come Back Every Year?

Double Knockout Roses are perennials and will re-bloom each year.

How Often do Double Knockout Roses Bloom?

Double Knockout Roses bloom continuously. Your shrub will bloom 2-inch flowers every 5 to 6 weeks from spring to late fall.

Closeup of coral-colored rose buds.

Where To Buy Double Knockout Roses

Where To Buy Double Knockout Rose Bushes

You can purchase Double Knockout Rose shrubs from Nature Hills Nursery.

Seeds are harder to find, but pre-grown shrubs are available at most nurseries in North America.

The Beauty of Double Knockout Roses

Closeup  of single dark pink rose bloom.

Double Knockout Roses are easy to care for and great for every skill level. They add bright colors to any garden and bloom for a large part of the year. Showcasing their beautiful continuous flowers from Spring to late Fall.

Every garden can benefit from having a drought-resistant and disease-resistant plant that needs little in the way of maintenance. Just plant your Double Knockout Roses and watch them bloom!

Are you one of the many fans of Double Knockout roses? We’d love to hear tips or suggestions in the comments section below! For more rose reading, click here for our other roses blog posts.