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6 Best KnockOut-rose Fertilizer: Review and Buying Guide

Knock Out roses are recognized for their ease of care, long blooming season with repeat blossoming, and enhanced disease resistance compared to typical tea roses. Make sure to fertilize regularly. If you want to see glossy foliage and vivid blossoms on your Knockout-Roses, you should fertilize them regularly.

It is important to remember that too much nitrogen will result in excessive foliage and fewer flowers. Choose a location where your Knock Out roses will receive 6 to 8 hours of direct sunlight every day. They can take little shade, but they thrive in full sun.

When young, Knockout-Roses might be sensitive to fertilizers. They may flourish in a broad range of environments, from zones 7 to 11, from spring until frost. But determining the optimum fertilizer for Knockout-Roses and which nutrients should be included in those fertilizers is critical.

So, let’s start with the question: What nutrients should be included in fertilizer, and what should be kept in mind when purchasing?

A lack of phosphorus may result in leaf loss, weak flower stalks, and closed buds. Phosphorus supports healthy root development and enormous flower output, whereas nitrogen promotes robust and healthy leaf growth.

Because the ability of a rose to create blossoms is held in its leaves, nitrogen promotes healthy foliage, which increases the number of blooms.

Potassium, also known as potash, helps Knockout-Roses that have been injured by insects, illnesses, or harsh weather conditions recover.

Potassium shortage can produce leaf margin browning, fragile flower stems, and undeveloped buds.

Macronutrients such as magnesium, calcium, boron, zinc, sulfur, copper, manganese, and iron are also required for roses to grow.

However, all elements must be in balance; thus, look at fertilizers’ NPK ratio, which shows the proportion of volume supplied to nitrogen, phosphorus, and potassium. For Knockout-Roses, an N-P-K ratio of 1-1-1 is recommended.

Now, my friend, we are just getting started. We will show you some of the best and suitable fertilizers to help your geranium get more healthy. 

6 Best Fertilizer for Knockout-Roses

We have listed the top best products that are available on the market. You can easily choose the best product from the list of fertilizers at a glance.

 So go through the list, and you’ll find the information in detail in this article.

Best fertilizer for knockout roses

FertilizersSpecificationCheck Price On
Miracle-Gro Rose Plant Food Rose Fertilizer
  • Instantly feeds to grow bigger, more beautiful roses versus unfed plants
  • Feed every 1-2 weeks
  • Endorsed by the American Rose Society
  • Use with Miracle-Gro Garden Feeder or any watering can
  • Guaranteed not to burn when used as directed
Jobe’s 09423 Organics Flower & Rose Granular Fertilizer
  • Product Dimensions: 6 x 2 x 9 inches
  • Item Weight: 4 Pounds
  • Target Species: Helps resist disease, insects, and drought during the 
  • growing season
  • Item model number: 9426
  • Applying requirement: Apply at planting and every 6 weeks
BioAdvanced 701260B 32Oz All in 1 Rose Care
  • Item Weight 2 Pounds
  • Liquid Volume 32 Fluid Ounces
  • PLANT FOOD: Promotes strong roots and beautiful blooms
  • INSECT KILLER: Kills Japanese Beetles, Aphids, Leafhoppers, and other listed pests
  • DISEASE CONTROL: Fungicide controls Black Spot, Powdery Mildew, Rust, Southern Blight, and more
  • RAINPROOF PROTECTION: Systemic rainproof protection lasts up to 6 weeks
  • RESTRICTIONS: Not for sale in NY, CT, MD, VT
Osmocote Smart-Release Plant Food
  • Product Dimensions: 4.2 x 7 x 13.5 inches
  • Item Weight: 8.1 Pounds
  • Target Species: All plant varieties
  • Manufacturer: Scotts Miracle-Gro
  • Item model number: 274850
  • Included nutrients: 11 essential nutrients
  • Feeding Time: For up to 6 months
Scotts Rose & Bloom Continuous Release Plant Food
  • Product Dimensions: 3 x 5.5 x 9.5 inches
  • Item Weight: 3.1 pounds
  • Manufacturer: Scotts - Mixing Warehouse Items
  • Item model number: 200950
  • Feeding requirement: Feeds up to 2 months
Down to Earth Organic Rose & Flower Fertilizer
  • Package Dimensions: 11.02 x 8.19 x 3.58 inches
  • Item Weight: 5.37 pounds
  • Manufacturer: Down To Earth All Natural Fertilizers
  • Coverage area: 100 square feet
  • Common Ingredients: Fish Bone Meal, Langbeinite, Blood Meal, Alfalfa Meal, Seabird Guano, Rock Phosphate, Humates, and Kelp Meal

1. Miracle-Gro Rose Plant Food Rose FertilizerBest fertilizer for knockout roses

This is our best recommendation for rose fertilizers. It is a water-soluble fertilizer that increases nutrient absorption in rose plants. It is simple to apply, not just because it is pretty helpful to this delicate plant.

It will be beneficial to you. This fertilizer is combined with water, making it more straightforward for plants to absorb nutrients. We can confidently state that this is the finest fertilizer for knock-out roses and other varieties of roses.

This Miracle-Gro may be used both in the ground and within the container. Miracle-Gro states that its rose food is safe for other flowering plants, and they recommend an 18-24-16 mix for healthy roses. You won’t have to be concerned about where you plant your roses.

This is recommended for usage throughout the growing season and should be fed to your plants every one to two weeks. It is a well-known brand for feeding roses. It is also high in magnesium, which is a necessary plant mineral for proper seed germination and the development of buds. This 18-24-16 fertilizer will provide you with rapid results, robust growth, and beautiful foliage in return.

Main Features

  • Instantly feeds to grow bigger, more beautiful roses versus unfed plants
  • Feed every 1-2 weeks
  • Endorsed by the American Rose Society
  • Use with Miracle-Gro Garden Feeder or any watering can
  • Guaranteed not to burn when used as directed

The things that might be bothering you: You may need to spend more on this if it is blooming season.


2. Jobe’s 09423 Organics Flower & Rose Granular FertilizerJobe’s 09423 Organics Flower & Rose Granular Fertilizer

Jobe’s Organics Flower is also rated by the USDA on OMRI for organic gardening as one of the most reputable names in organic fertilizer.

Jobe’s Organics has grafted this granular fertilizer to make it even easier to use. This powdered fertilizer is also engineered to release gradually, lowering the risk of fertilizer burn.

Jobe’s Biozome is a beautiful feature of this product. This aids in the breakdown of material, allowing your flowers to appear better faster. Assume, however, that you use a certified organic product, such as Jobe’s Organic. In that scenario, you may be sure that no hazardous chemicals were utilized to produce your garden.

Biozome, which contains Archaea, raises the product’s N-P-K level to 3-5-3. This promotes the fast decomposition of organic materials and minerals in the soil, allowing roots to absorb more easily.

The nitrogen concentration is 3 percent, the phosphorus amount is 5%, and the potassium content is 3%. As a result, it is utilized as a multifunctional fertilizer. The fertilizer is most effective when applied at the planting time and then every six weeks after that.

This fertilizer can help keep your soil healthy by preventing it from pests and diseases. It also has a chemical that protects your flowers from disease, insects, and even drought. As a consequence, your plants will be able to flourish even under drought-like conditions.

Main Features

  • With an NPK ratio of 3-5-3, it has a high phosphorus concentration.
  • Pets and children are welcome here.
  • OMRI has granted its seal of approval (Organic Materials Review Institute).
  • Biozome technology is included in this product.
  • Every pack includes a pre-measured spike to make measurement a breeze.
  • The granular formulation has a slow-release mechanism.
  • The fertilizer is not getting burnt.

The things that might bother you are that it attracts flying insects, so it’s best used outside gardening instead of indoors.


3. BioAdvanced 701260B 32Oz All in 1 Rose CareBioAdvanced 701260B 32Oz All in 1 Rose Care

Rose and floral spray concentration in one. Bayer Advanced All-In-One Rose and Flower Care – Concentrate protect roses, hibiscus, iris, and other flowers and shrubs for 6 weeks against serious issues. Aphids, Japanese beetles, leaf miners, whiteflies, and other pests are frequent insects that attack roses and flowers. Black spot, powdery mildew, and rust are all controlled by this product.

The major components are potassium phosphate, ammonium sulfate, urea, copper sulfate, iron, manganese, and zinc sulfate. It’s adaptable enough to work with both indoor and outdoor plants.

This fertilizer provides more fertilizer in a shorter period and encourages quicker plant development than other fertilizers. However, keep in mind that you must feed your plants every one to two weeks during the growing season. You’ll get quick results, robust growth, and luscious foliage in return.

Main Features

  • Item Weight 2 Pounds
  • Liquid Volume 32 Fluid Ounces
  • PLANT FOOD: Promotes strong roots and beautiful blooms
  • INSECT KILLER: Kills Japanese Beetles, Aphids, Leafhoppers, and other listed pests
  • DISEASE CONTROL: Fungicide controls Black Spot, Powdery Mildew, Rust, Southern Blight, and more
  • RAINPROOF PROTECTION: Systemic rainproof protection lasts up to 6 weeks
  • RESTRICTIONS: Not for sale in NY, CT, MD, VT

The things that might be bothering you: Overwatering or underwatering with this fertilizer can cause damage to the roots.


4. Osmocote Smart-Release Plant FoodOsmocote Smart-Release Plant Food

Osmocote Smart-Release Plant Food Plus is suitable for use on a wide variety of plants, including flowers, fruits, vegetables, trees, and shrubs. Because it grows well in a range of settings, it may be utilized both indoors and outdoors. When applied according to the directions, this product assures that your plants will not be burned.

This fertilizer contains magnesium at 1.3 percent, sulfur at 6.0 percent, boric acid at 0.02 percent, copper at 0.5 percent, iron at 0.46 percent, manganese at 0.6 percent, molybdenum at 0.02 percent, and zinc at 0.5 percent, all of which are essential elements for blooming plants.

Aside from that, the fertilizer’s no-burn composition allows you to use the solution for summer-grown plants without issue. This product is intended to nourish and enhance the root and promote healthy growth above the soil.

Finally, because of the slow-release nature of the powdered plant food, you only need to use it once every six months. One application of this plant food may last up to six months, making it excellent for forgetful gardeners.

This fertilizer application procedure is straightforward. You may either sprinkle the granules on top of the soil and then water them in, or use a watering can combine 1 scoop of granules with 2 gallons of water.

Main Features

  • The fertilizer can be mixed in a watering can or applied directly to the soil.
  • Slow-release granules with a resin coating and a semi-permeable porosity.
  • Designed to work with any plant kind, in any environment.
  • Plants can be fed for up to 6 months with just one application.
  • Potted plants can be used both indoors and outdoors using this container.
  • It has a 15-9-12 mineral blend in it, as well as 11 other necessary nutrients.
  • No-burn promise when used according to the instructions.

The things that might be bothering you: The only thing to remember is that after the nutrients are supplied to the plants, the pellets containing the nutrients will not dissolve.


5. Scotts Rose & Bloom Continuous Release Plant FoodScotts Rose & Bloom Continuous Release Plant Food

This Scotts Rose & Bloom fertilizer will provide an extra boost to your Knockout-Roses during the growth season. This fertilizer works by gradually giving nutrients to your Knockout-Roses. Over two months, this fertilizer will provide them with the nourishment they require to grow.

It’s easy to use; simply pour some on top of the ground. Assume you have other flowering plants in your annual or perennial garden. In such an instance, you may disperse the fertilizer over the area by pouring it into the top 1-3 inches of soil or mulch, whichever you choose.

Because the recipe is so safe, you may have total confidence in the firm. The fertilizer contains phosphorus, which assists in the production of high-quality blooms by keeping the plants well-fed.

You’ll enjoy its versatility if your yard contains a wide range of plants, not only Knockout-Roses. In addition, if you don’t want to spend a lot of money on various types of rose fertilizer.

The most significant part is that it may be taken directly from the bag by pouring it in, but remember to read the directions on the back. Loosely mix the mixture into the soil, on the other hand, is more suitable and will provide more significant results. On the other side, you only need one cup for every 30 square feet of area, making it quite economical.

Main Features

  • Simple to mix with water. Easily absorbed.
  • After only a few weeks of use, instant feeding shows impressive outcomes.
  • It can be applied to a wide range of plants.
  • This is an entirely risk-free product.
  • Phosphorus is abundantly present.
  • It can be put in containers or on the ground.
  • Avoid setting fire to your plants.
  • It’s great for all kinds of plants, but especially for Knockout-Roses.

The things that might be bothering you: It has to be used every week. Therefore it’s not the best option if you don’t have the time to do so.


6. Down to Earth Organic Rose & Flower FertilizerDown to Earth Organic Rose & Flower Fertilizer

The Down to Earth organic rose, and flower fertilizer combination is the ideal choice for Knockout-Roses. Because it contains no hazardous chemicals, this chemical-free organic fertilizer is beneficial to the environment. Furthermore, the additional nutrients it offers will help your Knockout-Roses grow bigger and healthier.

The NPK ratio of the Rose & Flower mix is 4-8-4, making it the ideal fertilizer for creating stunning blooms with bright colors and pleasant fragrances. It is high in nutrients such as nitrogen, phosphorus, potassium, and traces of other minerals that stimulate fast plant development.

Phosphorus is essential for flowering plants. Because this flower fertilizer has a high amount of nutrition, you may expect more blooms due to applying it.

This fertilizer contains elements that are good for the soil, so it’s a win-win scenario. Fishbone meal, blood meal, langbeinite, rock meal owing to, kelp meal, and humates are among the components in the combination. These organic compounds will be absorbed into the soil and offer food for soil microorganisms to digest.

Because organic fertilizers are organic, they are safe to use around children and pets. However, unlike synthetic fertilizers, they will not harm or even kill your plants. This fertilizer is not sensitive to young plants, so you may use it without fear while planting fresh flowers.

Main Features

  • The extra phosphorus will produce vibrant flowers.
  • Recyclable cardboard box.
  • Organic fertilizer is recognized by the OMRI as a source of nutrients.
  • Flower fertilizer that can be applied at any time of year as a stand-alone product.
  • Fish meal, alfalfa meal, kelp, and blood meal are included in the recipe.
  • Fishbone meal and rock phosphate are among the organic ingredients found in this blend.
  • It’s also great for bulbs, other flowers, and even edibles like herbs and vegetables.

The things that might be bothering you: Because the ingredients will attract dogs, so it’s best to bury it about an inch deep.



  • Question: Are coffee grounds good for knockout roses?

Answer: Roses enjoy coffee grounds, but too much too soon will cause a terrible nitrogen burn and destroy your roses. Never put coffee grinds right close to a plant.

  • Question: What is the best mulch for knockout roses?

Answer:  Mulch Knock Out roses in the spring with pine straw or a similar substance, then replace the mulch in late summer or early fall. Roses benefit from two to three inches of mulch.

  • Question: How often should you put coffee grounds on roses?

Answer: Half a pound of old coffee grounds to 2 gallons of water per rose is a reasonable rule of thumb. When your roses begin to bloom in the spring, use coffee grinds to fertilize them. The nitrogen will provide them with an additional surge of energy. April and May are great months.

  • Question: What kind of fertilizer makes flowers bloom?

Answer: Use a fertilizer with a low nitrogen content, a high phosphorus content, and a small amount of potassium to increase floral bud formation. I recently bought a liquid fertilizer with nutrient analysis of 5-30-5, perfect for flower production.

  • Question: What should you not plant around roses?

Answer: The University of Missouri Extension advises against growing big shrubs and trees near roses because they will compete for resources with the roses. Large shrubs and trees can also obstruct sunlight and impede airflow around foliage, causing difficulties for rose plants.significant

Final Word

Most of the fertilizers on our list of the 6 Best rose fertilizers are organic. Most gardeners want a fertilizer containing all the specific nutrients needed by Knockout-Roses, which delivers on both measures.

Whether you’re a dedicated specialist rose grower or a sunny weather gardener looking for easy fertilize-and-forget rose food, our collection has something for you.

But before choosing, we advise getting your soil tested first before deciding on organic or synthetic fertilizer and what type of NPK mix you require. As a result, think about the N-P-K ratio of your trees’ nutritional needs.