Knockout roses, also known as Rosa ‘Knock Out’, are a popular and low-maintenance variety of roses that produce vibrant and long-lasting blooms.
These roses are known for their disease-resistant qualities, making them an ideal choice for gardeners who want beautiful roses without the hassle of constant maintenance.
Knockout roses come in a variety of colors, ranging from bright pink and red to soft yellows and whites. They can be grown in containers or as a part of a garden bed, making them a versatile choice for any landscape.
Choosing the correct fertilizer is crucial to the health and longevity of knockout roses. These roses require fertilizers that are rich in nutrients such as nitrogen, phosphorus, and potassium.
A slow-release fertilizer is often recommended, as it provides a steady supply of nutrients to the plants over time.
It’s important to follow the instructions on the fertilizer packaging carefully and not to over-fertilize, as this can lead to weak stems and damage to the roots.
Regular fertilization can help promote healthy growth, strong stems, and vibrant blooms, ensuring that your knockout roses remain a beautiful and long-lasting addition to your garden.
For that reason, in this post we are going to discuss what to look for in the best knockout rose fertilizer.
Table of Contents
What is the best fertilizer for knockout roses?
Here is a quick preview of our top 5 picks
- Miracle-Gro Rose Plant Food
- Bayer Advanced All In One Rose & Flower Care
- Espoma Rose Tone
- Dr. Earth Total Advantage Rose & Flower Concentrate Fertilizer
- Jobe’s Organics Granular Plant Food
How to choose the right fertilizer for knockout roses?
Knockout roses are a trademarked variety of shrub rose that was introduced in the year 2000.
They are incredibly easy to grow and have quickly become one of the most popular rose varieties grown in North America. They are heat tolerant and cold hardy, disease-resistant, and “self-cleaning”.
This means that they push the old blooms out of the way when a new bud is formed, eliminating the need to deadhead spent flowers. The development of self-cleaning roses considerably reduced the amount of maintenance needed to be done by the homeowner to promote continuous blooming.
You may also enjoy reading: Should You Deadhead Knockout Roses?
Like most other flowering shrubs, knockout roses grow best when they are given the proper growing condition, including a regimen that provides proper fertilization.
In general, knockout roses are heavy feeders, requiring frequent feeding for optimum growth. “Heavy feeders” have a higher nutrient requirement than other plants usually due to fruit or blossom formation.
All plants have fifteen essential nutrients that are absolutely necessary for plant functions and growth: nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, sodium, boron, chlorine, manganese, iron, zinc, copper, molybdenum, and nickel.
Of the fifteen essential nutrients nitrogen, phosphorus and potassium are needed in the highest quantities.
Nitrogen will promote lush, green, vegetative growth; phosphorus strengthens the root systems and encourages beautiful blooms; potassium encourages vigorous growth and helps roses protect themselves from pest damage, drought, and cold.
To encourage strong, healthy knockout rose bushes teeming with blooms a well-balanced fertilizer (containing nitrogen, phosphorus, and potassium) should be applied to replenish nutrients in the soil.
The choice of an organic or inorganic/synthetic fertilizer lies in the hands of the gardener and their growing philosophy. The market is saturated with a variety of fertilizer options available for roses: organic, synthetic, granular, liquid, water-soluble, slow-release.
Regardless of the type of fertilizer purchased, it should be applied initially when there is 4-6” of new growth on the plants. For granular fertilizers, plant food should then be applied at the recommended rate every 4-6 weeks during the growing season after the initial application.
Liquid fertilizers are meant to be applied more frequently and are delivered at the time of watering.
No matter the type, remember fertilizers are essentially salts and need to be watered well into the soil to prevent damage to the roses’ roots.
The Best Fertilizer For Knockout Roses
Miracle-Gro Rose Plant Food
- Nutrient Ratio: 18-24-6
- Endorsed by the American Rose Society
Miracle-Gro Rose Plant Food – An industry leader in conventional fertilizer products, Miracle Gro’s Rose Plant Food is a water-soluble fertilizer formulated specifically for rose bushes.
This rose food promotes beautiful blooms and lush foliage by immediately providing nutrients to the plants after application. With a nutrient ratio of 18-24-6 to encourage blossom development, dilute 1 tablespoon of the granules per 1 gallon of warm water to feed outdoor plants.
Miracle-Gro Rose Plant Food is endorsed by the American Rose Society and guaranteed not to burn rose bushes when used per the label instructions.
Bayer Advanced All-In-One Rose & Flower Care
- Insect and Disease control up to 6 weeks
- Easy to apply
- Nutrient ratio 6-9-6
Bayer Advanced All-In-One Rose & Flower Care – An all-in-one product with proven results, the Bayer Advanced Rose & Flower Care delivers plant essential nutrients to roses while simultaneously providing insect and disease control for up to 6 weeks after application.
The easy to apply fertilizer granules should be sprinkled around the base of the shrub at a dosage recommended on the label, and then well watered into the soil to move nutrients to the root zone for plant uptake.
A nutrient ratio of 6-9-6 in Bayer Advanced all in One Rose & Flower Care provides a nearly balanced amount of nitrogen, phosphorus, and potassium for strong, healthy plant growth.
Espoma Rose Tone
- All Natural Organic option
- 15 essential nutrients
Espoma Rose Tone is a fantastic all-natural and organic fertilizer option. This makes it a great option when searching for the best plant food for knockout roses.
Espoma Rose-tone provides gardeners with a long-lasting, premium plant food specially formulated for roses.
It contains all of the essential plant nutrients needed for plant functions and growth and is also enhanced with living microbes to increase soil quality. Espoma Rose Tone contains no sludges or other toxic ingredients making it environmentally safe.
For individual rose plants, sprinkle 1 ¼ cup around the base of each plant and work slightly into the soil. For rose beds, apply at a rate of 6 pounds per 100 square feet.
Water well after application to move nutrients to the roots of the rose bushes.
Dr. Earth Total Advantage Rose & Flower Concentrate Plant Food
- Designed to promote larger and more abundant rose blooms
Dr. Earth Total Advantage Rose & Flower Concentrate Fertilizer – Formulated with proprietary PreBiotic® and ProMoisture Hydrate®, Dr. Earth Total Advantage Rose & Flower Concentrate is formulated to feed plants naturally and promote larger, more abundant blooms.
The patented PreBiotic® consists of soluble sugars to provide food to existing soil microbes while ProMoisture Hydrate® assists in the hydration of soil biotics, keeping them alive and hydrated in extreme heat or cold.
For optimum results, dilute 4 tablespoons of Total Advantage Rose & Flower Concentrate per gallon of warm water and apply to rose bushes at the rate on the label instructions.
Jobe’s Organics Granular Plant Food
- Nutrient ratio 3-5-3
Lastly, let’s talk about Jobe’s Organics Rose and Flower Plant Food.
This is an organic plant food that is OMRI-certified. It has an all-around good nutrient ratio of 3-5-4.
Additionally, it contains biozome which can do a number of different things for your plant. For example, it works great to protect your flowers from disease as well as other insects. It also can help to increase the quality of your soil and increase root mass.
Lastly, it is granular fertilizer. In fact, it comes in a pre-measured spike. This type is sometimes preferred over a liquid fertilizer as fewer mistakes can be made. However, with that being said, there is a water-soluble option available as well.
When Is The Best Time To Feed My Knockout Rose Bush?
Now that we have narrowed down the type of plant food to use, let’s briefly talk about when to feed them.
The good thing to know about knockout roses is that they are very difficult to overfeed, making them very easy to maintain.
Many people like to start by feeding them with a slow-release fertilizer in early March. That way when they are ready for food in April the nutrients will already be in the soil ready to be absorbed.
If you don’t plan on using a slow-release option and want to use a water-soluble fertilizer such as Miracle Grow. It is important to wait until the plant has gone through its first bloom cycle. After this, you can follow the instructions on the label of your preferred plant food.
Lastly, Knockout roses tend to slow down, in early August. For that reason, discontinue using any plant food as they prepare for the fall season.
In conclusion, knockout roses are an excellent choice for gardeners looking for a low-maintenance yet beautiful variety of roses.
These roses require proper care and maintenance, including choosing the correct fertilizer for their unique nutrient requirements.
By selecting a slow-release fertilizer that is rich in the necessary nutrients and applying it correctly, you can ensure your knockout roses thrive and produce vibrant and long-lasting blooms.
With the right care, your knockout roses will be a source of beauty and enjoyment in your garden for years to come.
What type of fertilizer do you use for knockout roses? Please share with us your thoughts on what is the best fertilizer for knockout roses in the comment section below.