When planted right and in the right spot, Knock Out Roses are the easiest and lowest maintenance roses you'll ever grow. They can be grown in garden beds or containers.

Here's a breakdown of what you need to know to grow them like the pros...



Cultural Preferences



Soil Preferences

Knock Out Roses grow well in a range of soil types, but grow best in a moist but well-drained soil of average fertility. Constantly soggy or wet soil can be problematic. So make sure to plant in a well-drained site. 


How To Test Soil Drainage  

If you are uncertain about soil drainage in the area you intend to plant your roses, it's well worth taking the time to test the drainage before planting. 

To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions. A slower rate indicates poor draining soil and is a caution you need to improve drainage or look for plants that are more tolerant of wet or boggy conditions.


Soil pH

Knock Out Roses grow best in a moderately acid to neutral soil ranging from 6.0 to 7.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0. 


Testing Soil pH  

Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing shrub roses, it's a good idea to test the soil pH in the planting area. 

You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil SulfurAluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.





Light Preferences

Knock Out Roses thrive in full sun or part shade. To avoid onset of powdery mildew on leaves, as with all other roses, morning sun is necessary to dry the morning dew from their leaves. Filtered afternoon sun or dappled shade is fine. The densest growth and best flowering occurs with at least 5 hours of direct sun from spring through early fall, when plants are actively growing. 




How To Plant A Knock Out Rose

Scroll down for container planting instructions

TIP: Water the root ball deeply before removing the plant from its container.


Step 1

Start by digging your planting hole at least two to three times as wide and as deep or not much deeper than the root ball of your plant. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.


Step 2

Depending on the type, fertility and porosity of the soil in the planting area you might consider amending the native soil. When planting in dense clay or poor soils it is beneficial to thoroughly mix in some composted organic matter, bagged top soil, and/or a good planting mix at a 50/50 ratio with the soil removed from the planting hole. When planting in very sandy, quick-draining soil consider mixing in some top soil, peat moss or compost to help retain moisture. When planting in average to loamy, moist but well-drained soil there is no need for adding a soil amendment.


Step 3

To remove your rose from the container it was growing in first squeeze the sides of the container to loosen the root ball. Then, wearing thick gloves or wrapping the base of the plant with a thick towel or other material, firmly grasp the base of the plant and very gently try to lift and remove the root ball from its container. Be very careful not to damage your rose when removing it from the container. If the root ball is stuck in the container it's best to use a snipping tool or utility knife to cut the container away. After having removed the plant from the container, carefully loosen some feeder roots around the surface of the root ball. 


Step 4

Set your rose in the planting hole so that the top edge of the root ball is at or slightly above ground level to allow for settling. If the soil is somewhat slow to drain, plant with the root ball 2 or more inches above ground level. It may be necessary to place some of your backfill soil mixture in the bottom of the hole to achieve proper planting height.

NOTE: If the soil in the planting area is poorly drained (constantly soggy or wet) improve drainage or select a different plant species more tolerant of wet soils.  




Step 5

After setting your rose in the planting hole, use one hand to hold the plant straight while using your other hand to begin backfilling the soil mixture around the root ball, tamping as you go to remove air pockets. If the soil is dry, when you have filled the hole to the halfway point you can soak the soil. Then continue backfilling to the top edge of the root ball. If you are planting with the root ball above ground level, taper your soil mixture gradually to the ground level, essentially creating a raised mound. To avoid suffocating your rose, avoid placing any soil on top of the root ball.


Step 6 (Optional)

When planting a shrub rose in a location that is far from a water source, and in well-drained soil, you can use remaining soil mixture to build a 2 to 3-inch high water retaining berm (catch basin / doughnut) around the outside perimeter of the planting hole. This basin will help to collect water from rainfall and irrigation often reducing the need for hand-watering. The berm can be removed after a year when the plant has established itself.


Step 7 

Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, to stimulate early root formation and stronger root development you can also water you newly planted shrub with a solution of Root Stimulator, which reduces transplant shock and promotes greener, more vigorous plants.


Step 8

Apply a 1 to 2" layer of  shredded wood mulch or bark, or a 3- 4" layer of pine straw, around your newly planted rose. Avoid the use of freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of the rose as this could cause the bark to rot. There are several benefits to mulching around your newly planted rose. Mulch applied correctly will help retain the moisture and prevent weeds that would compete with your rose for water. 




How To Plant A Knock Out Rose In A Container



Shrub roses growing in pots appreciate a moist but well-drained soil. Constantly soggy soil will often cause root rot or other harmful or deadly plant diseases. Therefore, when planting in a container or pot, use a container with a drainage hole and a high quality potting soil or professional potting mix, or a 50/50 combination thereof. To enhance drainage and also help to hold moisture evenly throughout the container, you can also add 10-20% perlite or pumice to soil mixture. 

Choose a container that is large enough to allow for 2 to 3 years of growth before shifting up to a larger size container. This might mean your planting pot would be 8 inches or more in rim diameter than the root ball of your plant. 

Container color will matter as well. Not only will you want to pick a color of container that goes well with the flower and foliage color of your Knock Out Rose, you'll also want to pick a container that matches the style of your home or other structures and other plants in the surrounding environment. 

Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.


Container Planting Instructions


Step 1

Before filling your container with soil, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil. If you place gravel in the bottom of the container lay the fabric over it.


Step 2

To remove your rose from the container it was growing in first squeeze the sides of the container to loosen the root ball. Since most shrub roses have some thorns, I'd recommend wearing thick gloves or wrapping the base of the plant with a thick towel or other material when handling the plant. Then firmly grasp the base of the plant and very gently lift and remove the root ball from its container. Be very careful not to damage the plant when removing it from the container. If the root ball is stuck in the container it's best to use a snipping tool or utility knife to cut the container away. After having removed the plant from the container, carefully loosen some feeder roots around the surface of the root ball. 


Step 3

Pour a small amount of your soil mixture in the bottom of the container. Set your rose in the container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1/2 to 1" below the rim of the container.



Step 4

Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball.


Step 5

Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering.


Step 6 (Optional)

Apply a 1/2" layer of wood chips or sphagnum moss to soil surface for decorative purpose and to help conserve moisture. You can also incorporate low growing, spreading plants in your container planting that will serve as a permanent soil cover.



How To Care For Knock Out Roses



How To Fertilize Knock Out Roses


In The Ground

Knock Out Roses are fast growers and heavy bloomers that will benefit from fertilization. I suggest feeding as directed on the product label with a rose food or an organic plant food. Cease fertilization 2 months prior to the average first-frost date in your area.


In Containers

Feed your Knock Out Roses growing in a containers as directed on the product label with a slow-release granular or water soluble fertilizer listed for use in containers. 


Soil pH

Knock Out Roses grow best in a mildly acid to neutral soil ranging from 6.0 to 7.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0. 


Testing Soil pH  

Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing roses, it's a good idea to test the soil pH in the planting area. 

You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil SulfurAluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.





How To Water A Knock Out Rose 

Knock Out Roses grow best in a moist but well-drained soil. Constantly soggy or wet soil can cause root rot or other harmful plant diseases. So be careful not to over-water! 

TIP:  When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliar diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist, not wet.

 
At Planting Time

Immediately after planting deep soak the soil in the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost to stimulate early root formation and stronger root development, consider watering your newly planted Knock Out Rose with a solution of Root Stimulator. Root Stimulator reduces transplant shock and promotes greener, more vigorous plants. 


During the First Active Growth Season

In average garden soil you should not have to water your newly planted Knock Out Roses every day. More often than not, this causes soggy soil conditions that can lead to root rot and other harmful plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil damp to moist. 

Keep in mind that deep soaking less frequently, allowing the soil to dry out somewhat before watering again, is much better than splashing just a little water on the plants every day. Roses planted during the winter dormant season, when they are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!


Thereafter

When established, Knock Out Roses are moderately drought tolerant. Only during periods of summer drought will they require supplemental irrigation. If you see new leaves wilting, or the tips of new stems bending over during dry weather, this could be a sign your roses could use a good deep soaking. Check soil moisture and provide water only if necessary.




How To Prune A Knock Out Rose

Knock Out Roses do not require pruning however respond well to and can benefit from it.


Annual Pruning

In late winter or very early spring, before new growth begins to emerge, I usually do a hard pruning on my Knock Out Roses Roses. At this time I use a sharp pair of bypass hand pruners  to cut the shrub back to about 18 inches above the ground. This ensures that the plant will have a good habit and healthy blooms throughout the season. 


Maintenance Pruning

During the blooming season, spent blooms can be removed to encourage more blooms. When removing a spent bloom I simply snip them off at the base of the stem. Alternatively, you can cut the stem back to the first 5-leaf stem below the spent bloom.

Note:  Cease pruning your Knock Out Roses two months prior to the average first-frost date in your area. 

 



Plant Long & Prosper!

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