6 Best Fertilizer For Knockout Roses 2022 [Top Picks & Guide]

Knockout roses aren’t hungry feeders. Yes! You read that right, and it is true. But this doesn’t mean they don’t need fertilizer. They also need fertilizer to thrive and produce healthy long-lasting blooms like all other flowering plants.

But the question:

Are all the fertilizer best for knockout roses? Obviously not. That’s why I am writing this article to introduce you to the top fertilizer for knockout roses.

Let’s stop wasting your valuable time, and see what is the best fertilizer for knockout roses today-

In a hurry? Here is the quick recommendation for your knockout rose bush that you may buy right now-

Best Fertilizer for Knockout Roses- Comparisons

1.Jobe's Organics 9425W Knock-Out Rose Organic Fertilizer3-4-3
Miracle-Gro Water Soluble Rose Plant Food18-24-16
Osmocote 274850 Smart-Release Plant Food15-9-12
Bayer Advanced 701110A Rose Care Granules6-9-6
Espoma RT4 Rose-Tone Plant Food4-3-2
Burpee Organic Rose and Bloom Granular Plant Food4-6-4

Best Fertilizer for Knockout Roses- Reviews

1.Jobe’s Organics  Knock-Out Rose Granular Fertilizer

Jobe's Organics 9425W Knock-Out Rose Organic Granular FertilizerIf you are looking for easy to apply, nature-friendly fertilizer for your knockout roses? Here is the Jobe’s Organics 9425W knockout fertilizer for you. It is the most recommended rose food that is specially formulated for knock out rose bush. 

It comes in granular form. According to the granular analysis, it contains 3% nitrogen,4% phosphate,3% potash, and some other macro and micronutrients.

Good news;

The nutrients are coated for both quick release and slow-release. Quick-release nutrients dissolve fast and feed your hungry plant instantly. In contrast, slow releases nutrients release slowly and feed your plant continuously when the plant wants. Sound impressive, right?

Moreover, All the nutrients are derived from some organic and natural compounds that are completely safe for your plants, pets, kids, and environment.

You will be happy to know;

It has no toxic and harmful chemical that is proved by OMRI. Let’s see where the nutrients are derived and how they help you knockout rose plant-

Feather meal is the source of nitrogen in this fertilizer, and more nitrogen is essential for the beginning stage of the knockout rose plant. Because it plays an important role in photosynthesis and you know more photosynthesis means more green leaves and healthier plants.

Bone meal is the source of phosphorus and calcium. These macronutrients help your plant to root development and promote blooms.

Sulfate slat of potash is the source of potassium and potassium is essential for vigorous plant growth and health.

Also, it contains organic proceed manure that provides some macro and micronutrients and improves the soil health.

The best part of this rose plan food is

It contains Bizome. Biozome is a blend of healthy bacteria, Mycorrhizal fungi, and Archaea that improves the long-term soil quality promotes new growth, and makes your knockout plant disease, insect, and drought-resistant. Also, it has humic acid as environmental stress reviver.

To feed your established knockout rose plant-

Measure 1 ½ cups of fertilizer per foot of rose bush spread. Sprinkle at the drip line and water the plants. Repeat the process after four to six weeks. It can also be used in soil preparation. Read the product label for other dosages.


2.Miracle-Gro Water Soluble Rose Bloom Plant Food

Miracle-Gro Water Soluble Rose Plant FoodMiracle-Gro is the brand that manufactures some miracle products for specific plants. They study the plant behavior and prepare a product that composition is perfect for the plant.

Today, Miracle-Gro is providing a fertilizer that is best for every type of rose bushes including knockout rose.

Let’s see-

What nutrients does this fertilizer contain and why is it best for knockout roses?

The NPK ratio of this fertilizer is 18-24-16. According to the NPK number, it contains 18% nitrogen and 16% potassium that accelerate the new growth, lush foliage, and take care of the overall health of the knockout rose. The higher ratio of Nitrogen protects your knockout roses from yellowing leaves and other nitrogen deficiencies.

And it also contains a high amount of phosphorus and some other micronutrients that help you to get what you expect from your roses. The beautiful, healthy, continuous, and long-lasting blooms.

It is water-soluble fertilizer that can feed your rose plant instantly. Moreover, it may apply to other flowering plants.

Mix 1 tablespoon per gallon of water and feed your roses to get healthy plants and increases the bloom cycle.Repeat the application after 1-2 weeks.


3.Osmocote Smart-Release Plant Food

Osmocote 274850 Smart-Release Plant Food Plus Outdoor & IndoorIf you want a slow-release fertilizer for your knockout roses, Osmocote 274850 will be the perfect pick for you.

It contains 11 essential nutrients. All the nutrients release only the plants need. So, no need to worry about regular feeding. This fertilizer will take care of your roses up to 6 months after applying once. Sounds impressive! Right?

And you know-

Plants need more fertilizer in the active growing season. Because of this, you have to apply fertilizer more rapidly. But this fertilizer is specially formulated for solving this problem. It can release faster in the growing season.

Let’s see what the ratio of three essential nutrients is-

According to the NPK number, It contains 15% nitrogen,9% phosphorus, and 12% potassium. Besides, it also contains 1.9% calcium,1.4% magnesium,4% sulfur, and in small amounts of boron, copper, iron, manganese, molybdenum, and zinc.

All the nutrients are essential in the growing and flowering stage of knock out roses.

Sprinkle the 20 grams fertilizer granule for 2 square feet, mix with the top inch of soil, and water the plant. Or mix  20 grams of granule into 1-gallon water and pour the solution on the rose plant.


4.Bayer Advanced  All in One Rose and Flower Care Granules

Bayer Advanced 701110A All in One Rose and Flower Care GranulesBayer Advanced 70110A is the most popular fertilizer for knockout roses. Let’s see the features of its popularity.

You may know from the name-

It is an all in one rose fertilizer. That means it acts as a fertilizer, insecticide, and fungicide for your knock-out roses. Isn’t it cool?

As a fertilizer, it has the 6-9-6 NPK number that promotes the new growth of root, shoot, and blooms and also has 2% sulfur for chlorophyll formation.

As an insecticide, It contains imidacloprid that acts as an insect neurotoxin. It can kill most of the rose insects including aphids, beetle, bugs, caterpillars, thrips, whiteflies, and so on(see the affected insect list on the product label)

And as a fungicide, it contains tebuconazole as an active ingredient. It can control the common fungal disease of knockout roses such as black spot, powdery mildew, rust, and southern blight.

Do you find the best liquid fertilizer for roses? Good news; it is also available in liquid form.

If you need fertilizer to get the healthy, disease and insect-free knockout rose bushes and blooms, pick this fertilizer and apply it on plants by following the instructions.

Sprinkle 1 cupful granules (2 oz per quart water for liquid forms) on a rose bush, scratch the top inch soil, and water the rose bushes.


5.Espoma RT4 Rose-Tone Plant Food

Espoma RT4 4-Pound Rose-Tone 4-3-2 Plant FoodEspoma RT4 is a bio formulated fertilizer that especially manufactured for roses and flowers. The NPK number of this fertilizer is  4-3-2. Besides NPK, It has also 12 other nutrients including calcium and magnesium. 

The good news for knockout rose lovers;

It contains 1.1% water-soluble nitrogen and  2.6% water-insoluble nitrogen.How will it help your plants? The water-soluble nitrogen instantly feeds your plant after applying but the insoluble nitrogen releases slowly and feeds your plant continuously for a long time.

Isn’t it convincing for buying this fertilizer? But- wait, it has another feature that you may like.

All the nutrients of this fertilizer are derived from organic materials such as feather meal, poultry meal, bone meal, alfalfa meal, and so on. It also contains some beneficial soil microbes that increase the microbial activity of the soil.

Let’s be honest-

It has a smell like organic manure that you may not like.

To get healthy plants with long-lasting blooms-

At the drip line apply 1-1/4 cup around each of the knockout rose plants, scratch into the surface soil, and water the plant.


6.Burpee Organic Rose and Bloom Granular Plant Food

Burpee Organic Rose and Bloom Granular Plant FoodBurpee Rose and Bloom Granular Food is another best organic fertilizer for knock out roses that has 4% nitrogen,6% phosphorus, and 4% potassium. The perfect NPK ratio will help you to get healthy knock out roses with extra bigger blooms.

It also contains immediately and slow-release nutrients that can feed your plants continuously up to 3 months as well as instant feeding.

Big news:

This is the OMRI listed organic fertilizer. The OMRI certified that it has no chemical substances and the active nutrients are derived naturally.

Sprinkle 1 cup per knockout rose plants, scratch into the surface soil, water the plant, and get healthy plants with vibrant blooms.


How to Choose Fertilizer for Knockout Rose?

If you get a healthy knockout plant and bigger blooms, you should maintain a basic rule. 

You know:

Spring is the growing season of knock out roses, and they need more nitrogen this time. Because nitrogen helps the plant to make bushy with dark green leaves and sturdy stems. That’s why you need to apply more nitrogen-containing fertilizer in spring. (Our recommended: Osmocote 274850 Smart-Release Plant)

On the other hand, Summer to fall is the flowering period of knock out roses. They need extra phosphorus at this time. Phosphorus needs for vibrant and bigger blooms. So, apply more phosphorus-containing fertilizer in summer to fall. (Our recommended: Bayer Advanced 701110A)

When to Fertilize Knockout Roses?

kncokout roses blooms

When to Start Fertilizing Knockout Roses?

Start feeding your roses in spring. Remember you have to feed only the plants that have some true leaves. Never fertilize the roses when it has no leaves.

When to Stop Fertilizing Knockout Roses?

Stop feeding your shrub roses in late summer before the frost comes. It’s preparing time for dormancy and winter protection.

How often Fertilize Knock Out Roses?

Many gardeners’ gurus recommend fertilizing the knockout rose once every 2-3 weeks. It should be followed. But the schedule must be varied. Some fertilizers can release nutrients slowly and some instantly.

So you should apply fertilizer more frequently for instant releasing water-soluble fertilizer. On the other hand, there is no need to apply fertilizer frequently if you apply slow-release fertilizer at once. The best idea to read the manufacturer’s instructions to avoid over-fertilizing.

What Is The Best Time to Fertilize?

Your plant can be damaged if you don’t apply fertilizer at the right time of the day. Because applying fertilizer in full sun can burn the plant leaves. That’s why fertilize your knock out roses when the weather is calm and the sun will get tired.

According to the experts, Early morning and early evening may be the best time to apply fertilizer on knock out roses. You can also change the application type. Just consider that the weather isn’t too hot.

How Do You Fertilize Knockout Roses?

You know how much and how often you have to apply fertilizer on knockout roses. Now it’s time to fertilize the plant. There are no hard and fast rules for feeding the plant. But for being safe, you should follow some basic rules.

For outdoor roses-

At the drip line dig a hole about 10-12 inches across the plant. Fill the hole with the fertilizer granules, mix with the soil, and water the plant.

For potted roses-

Sprinkle the fertilizer on the edge of the pot, work on the top 1-2 inches of soil, and water the plant.


Don’t apply fertilizer at the same place and avoid the base of the plants. Add water before and after fertilizing on the knockout roses. Because applying fertilizer under stress conditions is harmful to plants. So, Make sure the soil of the plant remains moist.

Frequently Asked Questions

#Are coffee grounds good for knockout roses?

Coffee grounds are good for roses in the growing stage. Coffee grounds provide nitrogen to the plants. And you know, nitrogen is the essential plant nutrient that makes the plant healthy and bushy.

But the bad news; too much nitrogen promotes only vegetation without flowering.

#Are eggshells good for knockout roses?

Eggshells are the natural source of calcium and you know calcium is one of the required nutrients for plants. So, you can feed 1-2 tablespoons of ground eggshells to your roses.

#Is Epsom salt good for knockout roses?

Yes, Chemically Epsom salt also called Magnesium sulfate. And it can provide magnesium to your plant that is an essential plant nutrient. You can mix 1 tablespoon of Epsom salt into a gallon of water and pour the solution on the plant once per month.

#How do I make my knock out roses bloom more?

Everyone loves to get the roses with more and bigger blooms. You will be happy to know, you can easily increase the bloom cycle if you want. Here are the steps you should follow to get more bloom cycle-

Proper Watering

Apply 1 inch of water per week. Apply more if the weather is too hot. Don’t forget about the harmful effect of overwatering. Good drainage potting mix can help you reduce the chance of overwatering damage.

So, make sure the rose plants have good drainage facilities and grow in a good type of potting mix.

Regular Feeding

Feeding is necessary to make more blooms. Choose the best knockout rose fertilizer and feed your plant by following the instructions.

Remove Insects

The insect can spread many plant diseases and stunt plant growth. That’s why it is also necessary to get rid of insects. Organic neem oil or insecticidal soap may help you to keep the insect away from your knockout rose plants.

Also, don’t forget to prune your roses and deadhead regularly if you want more and longer-lasting blooms.

#Why did my knockout roses stop blooming?

It may happen for different reasons. Insects infestation, lack of watering, and feeding may be the main reasons.

But the most possible reason will be feeding incorrect fertilizer to the knock out roses. If you feed more phosphorus in spring, plants don’t develop roots and foliage. Because spring is the growing season, they need nitrogen more than phosphorus.

On the other hand, If you continue to feed more nitrogen in summer and fall, plants become bushy, and won’t produce flowers.

So feed more nitrogen in spring and more phosphorus in summer to fall. Hope your knock out roses start smiling with lots of blooms.

#What are the varieties of the knockout rose to grow more with less fertilizer?

There are different types of knockout roses. Almost every variety needs less fertilizer than regular roses, tea roses, and star roses. It is the main difference between knockout roses and regular roses.

Here is a list of some of the most growing varieties of knock out roses-

  1. Pink Rose.
  2. Rainbow Rose.
  3. Double Roses.
  4. Blushing Rose.
  5. Sunny Rose.

You can find the varieties and cultural resources in the American Rose Society. You can get help from the Rose Society to promote and culture your roses.


Knock out roses perform well in a wide range of soil types with a minimum amount of soil nutrients. So, never apply to overfertilize your roses. Always read the directions dosage that manufacturers provide before applying fertilizer.

I hope you have got the best fertilizer for knockout rose bushes. If you get the fertilizer, don’t thank me NOW. Feed your roses and improve the irrigation system.

If you get healthy bushes with bigger blooms and a rapid bloom cycle. Let me know. That will be the significance of my writing.

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