The 5 Best Fertilizers for Beautiful Knockout Roses

With the arrival of spring, comes the need to sprinkle a good fertilizer on your beautiful roses. You might be confused about when and what type of fertilizer should you use for them. Application of the right fertilizer at the right time will give your knockout roses the perfect growth nutrients to make them beautiful and healthy. So keep reading this article to know more about the best fertilizer for knockout roses.


What Is the Need for Fertilizers for Knockout Roses?

Knockout Roses are easier to grow as compared to other traditional roses. They are also known as “self-cleaning roses” as they have increased disease resistance. The Knockout Roses are often called shrub or landscape roses. These roses are the perfect plants to grow as they bloom throughout the season.​

Knockout Roses can be given an additional boost in terms of proper fertilizers to produce strong, gigantic canes which come with alluring buds with beautiful flowers. A fertilizer may help in nourishing your rose bushes and creating more blooms. A fertilizer should be placed in and around a Knockout Rose bush, especially where the roots are found.

How to Choose The Right Fertilizer For Your Beautiful Knockout Roses?

Knockout Roses can bloom even without fertilizer, but when they are treated with a proper fertilizer they produce healthy and spectacular roses. When you feed the Knockout Roses with correct nutrients, you prevent them from a wide variety of diseases. With so many options available in the market, it becomes difficult to choose the correct fertilizer for your roses. Let’s find out more about the features you should look for in a fertilizer.

Jobe Organics 9425W Knock Out Rose Organic Fertilizer Brown 2


It is always better to use an organic fertilizer for maintaining your Knockout Roses beautifully. Fertilizers come in different proportions of important plant nutrients to take care of your Knockout Roses and to complete their other basic needs. An organic fertilizer is considered to be ideal as it improves the quality of the soil by releasing nitrogen slowly into the soil. It is important to always rotate the type of fertilizer that you are choosing for your shrub. If you do not wish to go for a fertilizer then you can also opt for an enriching compound filled product.

Knockout Roses are known to be heavy feeders. There are fifteen essential nutrients which are required by the Knockout Roses to bloom perfectly - Phosphorous, Potassium, Nitrogen, Sulphur, Zinc, Copper, Molybdenum, Nickel, Boron, Sodium, Magnesium, Chlorine, Manganese and Iron. You might notice a three-digit number on the packaging of the fertilizers you choose for your knockout roses. This is known as the NPK ratio, which explains the percentage of nitrogen, phosphorus and potassium in a fertilizer. You should always pay attention to the percentage of nitrogen in lawn fertilizer. Excess amount of nitrogen in a fertilizer can cause excessive vegetation around the bush. This might result in the concealment of the blooming process.

The Negative Impact of Fertilizers on Environment

Fertilizers provide all the important nutrients to roses, but have we ever considered how they are negatively affecting our surroundings. Nitrogen is converted into ammonium or nitrate by the microbes in the soil so that it can be used by the plants. This nitrate gets easily released into the environment, hence, causing soil acidification. The released nitrate can penetrate the groundwater used by humans for domestic purposes, further posing as a threat to their lives.​

Cadmium is known to be present in soil in minute amounts. If large amounts of cadmium are released into sandy soils, then it can turn out to be a severe problem for the growth of the grass. High intake of phosphorus in a fertilizer might result in the accumulation of algae in the nearest water bodies which results in the death of aquatic animals as they are robbed of all the oxygen content in the water bodies. The effect of non-organic fertilizers on humans as well as plant health is a controversial topic till now. It is believed that the NPK ratio in the fertilizer damage crops faster than those which are not receiving fertilizers.

Top 5 Best Selling Lawn Fertilizers

After my thorough research on the net, I found these 5 products to be quite useful for the beautiful budding of Knockout Roses.

1. Grow More 13012 Magnum Rose Food, 4.5-Pound

Grow More 13012 Magnum Rose Food 4.5 Pound


Grow More is a brand developed by Dr. Tommy Cairns of the American Rose Society. This product is a water-soluble, easy to use concentrate.


  • Grow More is a formulation specially produced for all types of roses.
  • Highly concentrated product which contains 8% total Nitrogen, 10% available Phosphate, and 8% Potassium.
  • It reaches the roses directly through the roots and leaves.
  • Provides Chelated Micronutrients to the roses which revives them & makes them disease-free.
  • Available in a 4.5 pound pack.


  • Contains a high amount of phosphorous, which might inhibit the plant’s ability to take up micro-nutrients like iron & zinc.

2. Ross Rose & Flowering Shrubs Fertilizer Refills for Ross Root Feeder, 15-25-10 (Ideal for Watering During Droughts), 54 Refills

Ross Rose Flowering Shrubs Fertilizer Refills for Ross Root Feeder 15 25 10


Ross Root Feeder feeds the plants directly at the roots. This product is specially manufactured to provide a balance of nutrition for the roses. It is ideal to use for all kinds of roses and flowering shrubs.


  • A premium product made for fast, easy and mess-free fertilization.
  • Enters deeply into the roots of the plants and encourages deep root development.
  • This product is ideal for watering plants during droughts.
  • It is available in many different packaging.


  • Contains a high amount of nitrogen which might damage the grass in the long run.
  • Contains a high amount of potassium which might restrict the absorption of other nutrients.
  • Contains a high amount of phosphorous, which might inhibit the plant’s ability to take up micro-nutrients like iron & zinc.

3. Urban Farm Fertilizers Rose Garden Professional Rose Fertilizer. 1 Gallon. Makes 256 gals.

Urban Farm Fertilizers Rose Garden Professional Rose Fertilizer. 1 Gallon. Makes 256 gals.


Urban farm fertilizer is a professional, easy to use product which is specially formulated for roses. This product is perfect to be used in sprayers, drip-systems, hand-watering systems.


  • This is a liquid fertilizer with an NPK ratio of 5-5-3.
  • It is a super-concentrated product which is diluted with water in the ratio of 256:1.
  • The ingredients used in this product are of organic quality - mycorrhizae, humic acid, kelp, enzymes and minerals.
  • Formulated with 4% calcium as well.
  • Available in different packagings - 64 Gallons, 128 Gallons and 256 Gallons


  • If not used properly liquid fertilizer might result in the pollution of nearby water bodies.

4. Jobe's Organics 9425W Knock-Out Rose Organic Fertilizer, Brown

Jobe Organics 9425W Knock Out Rose Organic Fertilizer Brown


This product is an organic blend of three microorganisms - bacteria, mycorrhizal, and fungi. A unique species of Archaea are also used in this formulation to enhance nutrient absorption.


  • Can be applied to any type of roses - knockout roses, bare root roses or the traditional tea roses.
  • Comes in a granulated form with a slow-release timing so that it doesn’t harm the plants.
  • Specially formulated based on an exclusive Biome formula.
  • Easy to apply and easy to use with all the instructions mentioned on the package.
  • Available in different packagings - 4lbs, 6lbs and 16lbs. A 16 pound bag can last up to 6 weeks.


  • Not easily available in all parts of the USA.

5. Miracle-Gro Water Soluble Rose Plant Food, 1.5 lb.

Miracle Gro Water Soluble Rose Plant Food 1.5 lb.


Miracle-Gro rose plant food is one of the industry’s strongest leaders in the category of conventional fertilizer products.


  • This is a water-soluble concentrate which is specially formulated for roses.
  • The nutrient NPK ratio of this product is 18-24-6 developed for providing lustful roses.
  • For best results, you can use the product with Miracle-Gro Garden Feeder.
  • Easy to use instructions are mentioned at the back of the product labels.


  • You have to feed the plants every 1-2 weeks.
  • The content of nitrogen is too high in the product which might result in burn out of the plants.
  • The content of phosphorous is also high which might inhibit the plant’s ability to take up micro-nutrients like iron & zinc.


Out of the five products that I have discussed in this post, I feel most strongly about Jobe's Organics 9425W Knock-Out Rose Organic Fertilizer, Brown. This fertilizer is in the granular form so you don’t have to worry about reapplication of the product again and again. It can be reapplied every 6 weeks. It gives you the option to comes in different packaging of 4,6 and 16lbs. It is an organic granular fertilizer which is formulated with Biozome which makes it an environment-friendly option for the gardeners. Biozome is a combination of three microorganisms - bacteria, Mycorrhizal fungi and an extremely aggressive microorganism Archaea which can quickly break out into basic nutrients. 

This unique blend of formulation helps the gardeners to improve the long-term soil quality of the soil. The granulated fertilizer promotes the growth of the roses and also keeps them away from insects and diseases. The product is easy to use product with all the instructions mentioned on the packaging. There are no harsh chemicals in this product which could burn out the plants. Moreover, it is safe to use around children and pets. Every rose shrub might have a different requirement so it is better to research different fertilizers before choosing one for your Knockout Roses.

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