Best Fertilizers For Knockout Roses 2022: Reviews & Buyer’s Guide

1. Schultz 2. Scotts 3. Bayer Advanced
Schultz Best Fertilizer For Knockout Rose Scotts Bayer Advanced

The rose is the most popular flower in the world. Roses were also a symbol of beauty, love, friendship, greatness, prestige, health, character, mission, faith and belonging to power. Fertilization is one of the most significant parts of the rose growing process. So be choosy when you opt for the best fertilizer for knockout roses for your gardening needs.

Untreated oilseed roses become smaller, yielding lower yield and quality. They are more susceptible to disease, pests, and frostbite. To properly fertilize, one must know the basic rules of roses nutrition.

There is a very important balance between nitrogen, potassium, phosphorus and calcium fertilization in university fertilization. What is the best fertilizer for knockout roses? How to choose it?


Roses Nutrition/Fertilizer Needs

Roses are sensitive to salinization (with sodium and chlorine). It causes limited growth and the edges of the roses’ leaves turn brown and dry, just to increase the need for rose nutrients and come to the aid of the best fertilizers for knockout roses. In case of nitrogen deficiency, plants have reduced growth. First, the old leaves turn pale green, the new leaves become small and the internodes shorten. The bark often turns red.

1. Nitrogen

Ammonium nitrogen fertilization undergoes university displacement, which must be a balanced nitrogen fertilizer with nitrates and ammonium forms. Ammonium fertilization reduces the carbohydrate reserves in the plant.

In the case of nitrogen deficiency, plants need a reduced plant. The old leaves turn pale green. The small ones, which are closer to the bark turn themselves and the bark red.

2. Phosphorus

Phosphorus deficiency reduces the woodiness of the branches and the lack of rich colors. Restricting to the roots, the leaves become small. The leaves turn dark green to gray-green, firm, cartilaginous and shaped upwards. A sufficient number of conductive vessels turn purple. If you’re not doing it, unless measures are taken, the old leaves turn yellow and fall off prematurely.

3. Potassium

The yellowing of the leaves is maximum due to a deficiency of potassium and/or iron. Over time, the edges of the leaves turn yellow and the inhabitants remain green. The young leaves turn reddish-purple. Most of these elements are missing from roses planted and growing in sandy and peaty postage. A better part of their leaves become necrotic and fall off.

4. Magnesium

With magnesium deficiency on older leaves, but not the oldest leaves, chlorosis appears, the nerves and adjacent tissues remain green, the pattern begins to resemble a Christmas tree. The interspace areas of the leaf first turn yellow, then brown. The list’s interregional spaces turn yellow after brown.

5. Calcium

When calcium deficiency occurs, chlorosis appears on young leaves. The old leaves turn gray-green and their ends run down. Calcium is an indispensable nutrient for university. calcium is important for healthy tissues and functioning membranes. This chemical element is critical for good root growth.

Calcium is used for the study and physiological stability of plant tissue, forming healthy cell walls and is vital for integrating the cell membrane. Calcium makes universities more resilient to stress.

6. Boron

Nutrition with calcium and boron is good for proper and fast development of the root system. Boron is important for the good absorption and movement of calcium. The blossoms of the roses are small and the edges of the petals are curled. Roses` leaves become small, deformed, hard, short and curve down. Leaves and blossoms break easily due to lack of elasticity. Eventually, the top buds die.

7. Iron

Roses are sensitive to iron deficiency. In the case of iron deficiency in the youth leaf, it is located between mercury chlorosis. Upon treatment with chlorosis, provoke the tissues, leave them green, with a more severe deficiency the whole leaves turn yellow. The pink color also changes.

8. Magnesium

In magnesium deficiency, the symptoms are similar, but chlorosis is on the young but not the youngest leaves. There is green on the leaves – yellow chlorosis with green conducting vessels and their adjacent tissues, later becoming necrosis.

Basic Fertilization Periods In Roses

For proper care of our roses, we not only have to be aware of the rules but also follow our intuition. Monitor the development of your plants and apply fertilizers only following their life cycle. During the first year in accordance with the rules for planting roses, roses should not be nourished. Then (fall or spring of next year), follow the pattern of fertilization according to the stages of development of the roses. And most importantly, use only the best fertilizers for knockout roses.

1. First Nourishing Of Roses (April)

After pruning the roses in spring in the bud swelling phase – mid-April, or if spring is cold, at the end. This is a period of intense growth and the roses need nitrogen, so they are most commonly fertilized with nitrogen fertilizers or complex minerals with high nitrogen content.

It is this ingredient that is fundamental to the best fertilizer for knockout roses. Before fertilizer is introduced, it is recommended that the soil be watered with warm water to allow the roots to start working.

Application of mineral fertilizers: 25-30 g / sq.m. ammonium nitrate (in this form nitrogen is absorbed faster) or 30-40 grams of universal trace element fertilizer. In liquid form – 1 tablespoon of the above-mentioned fertilizers per 10 liters of water at a flow rate of 3-4 liters per rose bush.

2. Second Rose Feeding (May)

The Start of shoot growth – in the first ten days – mid-May. By this time the shoots are beginning to grow actively and the roses need nitrogen. Fertilizers imported in April can easily be washed away by spring rains or poorly absorbed in cold soil.

If you prefer fertilizing with mineral fertilizers – 10-15 g / sq. m. ammonium nitrate, 25-30 g / sq. m. m superphosphate, 10-15 g / sq. m. m potassium torus.

3. Third Nourishment Of The Roses (Late May-early June)

This is approximately the period of budding in roses. In this phenophase, they are fed with calcium nitrate (this fertilizer helps to form a green mass and prevents disease) – 1/2 tablespoons per liter per bush.

Application of mineral fertilizers during this phenophase: 15-20 g / sq. m. ammonium nitrate, 30-40 g / sq. m. m superphosphate, 10-15 g / sq. m. m potassium sulfate, potassium nitrate. Potassium is the element responsible for the formation of beautiful colors. Therefore, it is necessary among the ingredients of the best fertilizer for knockout roses.

4. Fourth Feeding (July)

This is the time usually after the first flowering of roses (during flowering, the roses do not feed). Roses are fed with complex fertilizers or trace elements (with sufficient potassium and phosphorus).
Application of mineral fertilizers for roses: 40-50 g / sq. m superphosphate, 15-20 g / sq. m. m. potassium salt.

5. Last, Fifth Nourishment

Roses should be fertilized again in August, in order to have beautiful and rich colors. This is the period after the second flowering. Nitrogen from late July is not used to prevent the formation of rose shoots that will not ripen until winter.

The mineral fertilizers imported this month for roses are 30-40 g / sq. m potassium fertilizer with magnesium, 40-50 g / sq. m superphosphate, 15-20 g / sq. m. m. potassium salt.

Methods For Fertilizing Knockout Roses

There are different methods for applying fertilizers to roses. The best fertilizers for knockout roses are applicable by any of these methods.

1. Gradual fertilization

Make a shallow annular groove 15 cm from the stem, being careful not to damage the roots. Fill the furrow with soil-mixed fertilizer and sprinkle it with soil. Experienced gardeners say that with this application, the fertilizer will gradually dissolve during watering or rain and the plant will receive all the necessary substances slowly over time.
It is important to remember that fertilizers should not be applied to moist soil, this can cause the roots to burn.

2. Foliar Fertilization

Foliar fertilization is a great opportunity for roses, so the plant quickly receives the necessary substances, absorbs them through the leaves, until the composition of the soil changes. In this way, organic fertilizers are also imported. Late (at dusk) evening watering and spraying are not recommended for roses, as moisture that does not evaporate can cause fungal diseases.

3. Mineral Fertilization

If you have young plants planted, it is good to fertilize them with organic fertilizers in the spring, but if older roses are predominant, fertilize with ammonium nitrate. Fertilization with ammonium nitrate can start as soon as the snow melts.

To ensure abundant flowering of roses, it is best to use some of the best fertilizers for knockout roses with potassium-phosphorus compounds in May. Fertilization is desirable to be repeated in June. In July, if possible, add 500 g of chicken manure to the solution.

How To Choose The Best Fertilizer For Knockout Roses?

It is undisputed that the fertilization of roses is extremely important for their good start. However, it also influences the supply of plants in the early stages of their development with optimal amounts of macronutrients. That is why we need to pay attention to the nutrients when looking for the best fertilizer for knockout roses.

1. The Term NPK

When we talk about the best fertilizers for knockout roses, we will often refer to the term NPK fertilizer. NPK is the abbreviation for Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen is required for the growth of roses. Phosphorus strengthens the roots and provides gorgeous flowers and leaves. Without potassium, the water supply to the plant is impaired.

The choice of compound fertilizers, which do not contain a high percentage of a total active substance, guarantees a higher percentage absorption and maximum efficiency of the selected product. The best fertilizers for knockout roses are a balanced formula for the percentage of nutrients. This helps them absorb faster from the soil absorption complex and, from there, help them absorb from the root system of the plants.

2. Type Of Fertilizer

The advantage of mineral fertilizer types is that you know the exact ratio of the substances they contain and you can get a very fast result. Before you start fertilizing with mineral fertilizers, you need to determine the type of soil in your garden to know which substances are rich or poor. Your next step is to find out what substances the soil and the plant need. Thus you will know how to choose the right fertilizer.

Organic fertilizers are generally all-natural fertilizers – manure, humus, compost, and there are industrial granular organic fertilizers. In addition to being a source of nutrients, they also improve soil structure. However, they also have drawbacks. They do not know what the ratio of the main nutrients is. They are also uncomfortable if your knockout roses are in a pot.

3. Nutrient Ratio

The three figures you find on the back of the fertilizer package indicate to you what the ratio of each of the main types of elements is. The first number always belongs to nitrogen (N), the second one is for phosphorus (P), and the third one is for potassium (K). For example, you can have 100 kg of fertilizer with a formula of 5-7-4. This means it contains 5 kg of nitrogen, 7 kg of phosphorus and 4 kg of potassium. The other 84 kilograms are other elements.

In most cases, the 5-5-5 versatile fertilizer will provide the nutrients all plants need for healthy growth. However, it is best to choose an individual formula for your roses. And the best fertilizers for knockout roses have already developed it.

Roses have a long life and can stay in one place for more than 20 years. They are not as demanding on the soil as their root is a wild rose. However, because of their continuous flowering, they require many nutrients that are necessary to build flowers. Therefore, abundant fertilization is the most important condition for their successful cultivation. Please take a moment to review our suggestions for the best fertilizers for knockout roses. This will help you choose the right one.

Top 10 Best Fertilizers For Knockout Roses 2022

1. Schultz Bloom Plus

Schultz Best Fertilizer For Knockout Rose

Schultz 1.5Lb Bloom is a special rose fertilizer that provides the optimal amount of nutrients for your rosary with just one fertilizer. It is a specialized fertilizer, well balanced with nitrogen and phosphorus and perfectly enriched with potassium and magnesium, which is suitable for all groups of roses.

This fertilizer helps to dramatically increase flowering, color quality – size, porosity, and aroma. The magnesium content of the soil depends on the color of the pink colors – their saturation and brightness. Fertilizing with Schultz will not only help create new flower buds but also help preserve colors longer after they have been cut. And this is what we are looking for from the best fertilizers for knockout roses?


  • Durable
  • Gives quick results
  • Easy to use
  • Does not require mixing


  • Suitable for outdoor roses only

2. Scotts Rose and Bloom


What everyone is looking for from the best fertilizers for knockout roses is complex and special care that guarantees good plant development and long flowering. Scotts action is quick as it is absorbed directly during rain or watering. Its granular formula guarantees its complete absorption in the soil.

Usage is extremely easy. Spread it evenly on well-loosened soil and pour in plenty. This compound fertilizer will ensure stable development, better durability and abundant flowering of roses.


  • Convenient to use
  • 2-month effect
  • Does not burn the plant
  • Specialized in the flowering of roses


  • Highly dependent on rainfall

3. Bayer Advanced Lawn Weed & Crabgrass Killer

Bayer Advanced

Mineral multi-component fertilizer is used for all types of roses. It fully covers plant nutrient requirements. The high nitrogen content in the form of amide extends the life of the liquid fertilizer. Appropriate proportions of potassium and phosphorus stimulate the formation of flower buds and prolong the flowering period of plants. And not only this. This choice of ours for the best fertilizer for knockout roses also serves to promote strong roots.

Using it will be like a child’s play. Measure, mix and pour around the plant base. You can use it not only indoors but also for garden knockout roses. Its rain protection will last for six weeks.


  • Multiple nutrients
  • Insect control
  • Strengthens roots
  • Helps with diseases of the roses


  • Relatively high price

4. Urban Farm Rose Garden

Urban Farm

When it comes to the best fertilizers for knockout roses, they combine the benefits of organic and mineral fertilizers. This is exactly what Urban Farm does. It is a highly concentrated fertilizer produced based on organic matter. Such is mycorrhiza, humic acid, algae, enzymes and minerals in it. It is also handmade and properly blended.

Undoubtedly, one of the most important elements for roses is calcium. Urban Farm contains as much as 4% calcium, providing a healthy root system and a strong rose body. And it makes them resistant to stress.


  • Highly concentrated
  • Made from organic substances
  • A large amount of calcium
  • 100% water soluble


  • High price

5. Bonide Systemic Rose


A long-lasting compound fertilizer that deservedly ranks among the best fertilizers for knockout roses. The technological process used allows the preservation and integrity of all the properties necessary for the complete fertilization of roses. Imidacloprid has a high content of nitrogen, phosphorus, and potassium. The presence of fulvic and amino acids has a positive effect on the overall vegetative and generative development of roses.

A significant advantage of this fertilizer is the fact that it protects the roses against a variety of pests and diseases. Such as Caterpillars, Fungus gnats, Japanese beetle adults, Lace bugs and Leaf beetles. With Imidacloprid Insecticide, your roses will be fully protected and nourished.


  • Durability
  • Protection against diseases and harmful insects
  • Applied directly to the soil
  • Macro plus micronutrients content


  • Requires irrigation to be absorbed

6. Scotts Rose & Bloom


This long-acting rose fertilizer is recommended for all types of roses and flowering shrubs. Fertilizer granules release part of their nutrients immediately so that the plants are nourished from day one with all the essential essentials and microelements. It provides adequate nutrition with nitrogen and nutrients for 2 months.

The ease of use will fascinate you. Just sprinkle fertilizer on the soil without worrying that your roses will be burned. Scotts Rose’s safe formula will make sure that doesn’t happen.


  • Fast action
  • Content of all-important essentials and trace elements
  • Increases resistance to diseases and parasites.
  • Satisfies the special requirements of roses and flowering shrubs


  • Not suitable for all soil types

7. Bloom & Root Flower Formula

Bloom & Root

Concentrated fertilizer for all kinds of flowers. If you prefer to have one fertilizer suitable for fertilizing all the plants at home, then this is the universal fertilizer. Its formula can guarantee its complete absorption into the soil. It acts quickly, thanks to its direct absorption by plants during rain or watering.

Bloom & Root Natural contains a variety of organic ingredients, which puts it quite naturally among the best fertilizers for knockout roses. It is thanks to those fertilizers that plants will be nourished and flourishing.


  • Works all the way to the root of the plant
  • Contains organic ingredients
  • Fully absorbed in the soil
  • Suitable for fertilizing in spring and autumn


  • It is not specialized in fertilizing roses

8. Miracle-Gro Plant Food


This concentrated rose fertilizer that helps you nourish your roses not only in the garden but also in the plants you grow in pots on the balcony or at home. Provide the right amount of food for your decorative flowers by fertilizing them periodically with the Miracle-Gro Rose Plant. This will guarantee their quick and rich flowering.

By nourishing your plants with Miracle fertilizers, abundant flowering, beautiful, lasting and fragrant colors and improved resistance to changing climatic conditions are achieved. And that already deserves a place among the best fertilizers for knockout roses.


  • Approved by the American Rose Company
  • Easy to use
  • Safe formula
  • Contains all important nutrients


  • Requires frequent use

9. Fox Farm Organic Liquid Plant Flood

Fox Farm Organic

One of the essential characteristics of the best fertilizers for knockout roses is the organic base. Fox Farm has it. Its composition includes earthworm castings, bat guano, and Norwegian kelp. Rock phosphate is also added to them, which distributes energy evenly across the rose and thus stimulates its growth and flowering.

The concentration of liquid fertilizer for leafy ornamental plants is also higher in nitrogen, calcium, and magnesium. It is specially created to stimulate the formation of a flowering mass and keep it fresh and beautiful. Provides balanced nutrition to the flowers, makes their leaves shiny and healthy and gives them a long life.


  • Organic basis
  • Safe formula
  • Extends the life of roses
  • Enhances aroma


  • Relatively high price

10. General Hydroponics FloraBlend

General Hydroponics

Thanks to its organic basis, Flora Blend is another representative of the best fertilizers for knockout roses. It contains plant elements, seaweed, rock sand, and micronized leonardite. The formula is designed to take care of the proper root and foliage development of the main varieties of roses, as well as their abundant and prolonged flowering.

The complete set of trace elements prevents yellowing of the leaves caused by manganese and iron deficiency, to which this type of plant is particularly susceptible. Besides, this fertilizer produces fast results and has a long life.


  • Vegan product
  • Completely clean fertilizer
  • Organic basis
  • Very stable product with a long shelf life


  • Sometimes the packaging is defective

FAQs on Fertilizers For Knockout Roses

1. What Is The Best Fertilizer For Knockout Roses?

Fertilizers contain a variety of plant nutrients such as potassium, nitrogen, and phosphorus, which help roses grow faster and healthier. Because most soils do not provide such nutrients, fertilizing with the best fertilizer for knockout roses is a necessary part of growing them.

The basis of fertilizer composition is important. It would be good if it is organic. However, do not overlook the correct formula and ratio of NPK – nitrogen, phosphorus, and potassium. Choose a fertilizer that is easily digested by the soil and, accordingly, by your roses.

2. How Do I Make My Knockout Roses Bloom More?

Roses, especially re-flowering ones, need more nutrients. They require abundant nutrition with nitrogen, phosphorus, and potassium, as well as trace elements suitable for the most appropriate cultivation of roses. Choosing the best fertilizer for knockout roses that specializes in flowering will add to the long flowering and vitality of the roses.

3. What Causes Yellow Leaves On Knockout Roses?

When nitrogen is deficient, the leaves lose their green color. Red dots appear on them. The leaves become narrow and fall prematurely. First yellowing occurs on old leaves. Roses are particularly sensitive to nitrogen deficiency, such as roses in the spring, so you should feed them with ammonium nitrate or any complex nitrogen-containing preparation.

With excess nitrogen, the leaves turn dark green. The plants grow vigorously. The stems become soft and form little flowers that are easily affected by fungal diseases. Therefore, be careful when choosing a fertilizer. Only the best fertilizers for knockout roses contain the right nutrient ratio needed for the development of roses.

4. When Should I Fertilize My Knockout Roses?

Roses have characteristic periods during the growing season, during which each plant has certain nutritional requirements and needs different amounts of nutrients. Root and shoot growth is stimulated in the spring by pruning. During this time, the plant intensely absorbs nutrients, especially nitrogen.

In summer, complete fertilization with trace elements and organic fertilizers is required to form new shoots and to produce beautiful flowers. Autumn is for the accumulation of nutrients, for the maturation of the stem and the preparation of the plant for the winter requires phosphorus and potassium.

Best Fertilizers For Knockout Roses – Your pick?

Roses need more nutrients than all other plants. Therefore, the choice of a suitable fertilizer and its timely use are of particular importance.

Sometimes the root system of roses loses the ability to completely absorb nutrients from the soil. This occurs during periods of cold rain or after cold water. In such cases, foliar nourishment is resorted to: the plants are sprayed with solutions on the leaves early in the morning or in the evening so that the leaves have time to dry to avoid the development of fungal diseases.

Well-balanced and varied nutrition enables roses to express themselves in all their splendor: to give us a larger, brighter color that lingers longer on the bush or as a cut in a vase. This is reason enough for us to choose the best fertilizer for knockout roses – they deserve it.