Fertilizing Knockout Roses: How To Tips | Recommended Fertilizers

The patented Knock Out Rose is a family of compact rose bushes and a few tree variants best known for their low maintenance requirements and disease resistance. The red flower colored Knockout first hit the market in the year 2000.

Knock Out roses grow best in USDA hardiness zones 5 to 9. The common shrub version reaches a width of 3′ to 4′ feet.

Red Knock Out Roses in bloom
Flowering Red Knock Out Roses | BryanPollardPhotos-DepositPhotos

These plants grow in almost any location. Unlike normal roses, and they tend to thrive in poorer conditions than their kin.

Sometimes referred to as Knockout Rose, there are currently 11 official varieties in a variety of colors:

  • ‘Meibenbino’ – dwarf, bright red
  • ‘Radcon’ – bright pink
  • ‘Radcor’ – coral with yellow center
  • ‘Radgor’ – shell pink with yellow center
  • ‘Radral’ – brick orange fading to coral
  • ‘Radrazz’ – original red to pink variety
  • ‘Radsunny’ – yellow that fades to cream
  • ‘Radtko’ – red double-flowers
  • ‘Radtkopink’ – pink double-flowers
  • ‘Radwhite’ – white
  • ‘Radyod’ – light pink

These roses do not require fertilizing (except for tree varieties). But, fertilizing knockout roses will encourage healthy plants and more vibrant growth.

Related: When and How Long Knock Out Roses Bloom?

Best Rose Fertilizer For Knock Outs

As a general rule, a 6-12-6 NPK mix is ideal for any rose bush, but this ratio isn’t common on the market.

Thankfully, the Knock Out Rose does fine with a balanced formula and will tolerate a wider range of mixes.

For the best results, check your soil’s nutrient levels, either on the package or using a test kit.

Go with a commercial slow release fertilizer that best meets the deficiencies of your soil.

Here are three great commercial products that will all work well with your Knock Out Roses.

Burpee Organic Rose and Bloom Granular Plant Food

The Burpee organic fertilizer OMRI-approved (Organic Materials Review Institude). The food comes in a granular form providing rose plants with slow-releasing nutrients.

Its 4-6-4 NPK ratio is well-balanced and works well on any type of rose.

Jobe’s 9429W Knock-Out Rose Organic Granular Fertilizer

While not one of the bigger names, this fertilizer is also OMRI-approved. This fertilizer contains a 3-4-3 NPK ratio along with other important nutrients.

This fertilizer is formulated for Knock Out Roses. It also contains beneficial bacteria that aid in preventing infections and pest problems.

Miracle-Gro Water-Soluble Rose Plant Food

One of the most famous brands in house plant, vegetable garden, and rose care.

This newer liquid fertilizer formula has an 18-24-16 NPK ratio to encourage growth and longer-lasting blooms.

Only a small amount is needed (one tablespoon per gallon of water, to be precise). It is easy to apply as specified when watering your plant.

Details on: Organic Fertilizer for Roses

When Or How To Fertilize Knock Out Rose

As mentioned, Knock Out Roses generally don’t need fertilizer. But, there are times when you’ll want to feed them for better growth.

Under no circumstances should you fertilize your Knock Out Rose until after the first bloom cycle! This could severely damage the plant.

Fertilizing A Rose Knock Out Shrub Rose

Always water your rose before feeding, When plants have good soil moisture it reduces the possibility of chemical root burn.

Use one of the fertilizers mentioned above. Follow the instructions on its label.

As the growing season starts, fertilize only in the spring and early summer. Your Knock Out rose will be preparing for the winter in late summer. Feeding could result in vulnerable new growth.

More on Preparing Knockout Roses For Winter

Fertilizing a Tree Knock Out Rose

Unlike the shrub version, Knock Out Rose trees need plenty of organic nutrients to thrive.

You will want to mix rich organic materials, such as compost or manure and coffee grounds into the soil.

Add mulch every spring and fall, mixing in more organic material.

After the spring mulching, start pruning back any thin branches at the bottom. Trim back any larger healthy ones to allow better plant growth with its fresh meal.

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