The best fertilizer for double knockout roses should have a balanced NPK ratio, such as 10-10-10 or 20-20-20. In terms of forms and types, there are many options to choose from, including granular, liquid, and slow-release fertilizers, and they should all be able to fertilize white, all summer long red, yellow and pink Knock-out roses

Double knock-out roses are popular for gardeners due to their beautiful flowers and relatively low maintenance. To keep these plants healthy and ensure they produce plenty of blooms, it’s important to fertilize them regularly.

The best time to fertilize double knock-out roses is typically in the early spring, just as the plants start to grow, and then again in the summer during the active growing season.

It’s also a good idea to give the Knock-out Roses plants an additional boost with a fertilizer high in potassium in the fall to help them prepare for winter.

Let’s dive in!

Reviews: 5 Best Fertilizer For Double Knock-out Roses Of 2023 Reviewed

1. Jobe’s 09426 Granular And Jobe’s Organics 09026 Double Knock-out Roses 4lbs Complete Fertilizer Kit.

A pair of 4lb 09026 and 09426 from jobes was our editor’s pick of the best organic yet granular fertilizer for knock-out roses for sale on the market. It is also an all-purpose, if not a general purpose knock out roses fertilizer as it is safe to use on all types of annual and perennial flowers. Additionally, because it is an organic, granular fertilizer from Jobe’s 09426, it will not burn or damage delicate Double Knock-out Roses shoots, leaves and roots. Despite coming in a 5.5 lb. size package can professionally Feed up to 2,200 sq. ft. of knock-out roses in your garden area

Another advantage of using 09426 or the 09026 from Jobe’s fertilizer is that it is specifically formulated to promote abundant blooming in double knock-out roses and other flowering plants as it is a rich source of potassium.

Conversely, the potassium present in the Jobe’s Granular fertilizer overall ingredient ratio provides the perfect balance of nutrients to support strong, healthy growth and encourage the production of vibrant, colorful blooms by double knock-out roses.

Furthermore, despite only weighing 5.5 lb., it can ensure that your Double Knock-out Roses and other plants receive the nourishment they need without any negative side effects for over 7-14 days of fertilization schedule.

View on Amazon

2.Miracle-Gro Knockout Roses Bloom Booster 5.5 Lb. Water Soluble Fertilizer

Can you use Miracle-Gro on knock-out roses?100% Yes, you can use Miracle-Gro on knock-out roses. Due to this reason, we found the best water-soluble fertilizer for knock-out roses, as Miracle-Gro is a well-known fertilizer that can be used on various other flowering plants, including roses. In terms of its nutrient content, Miracle-Gro Water Soluble is also an NPK). Knock-out roses FERTILIZER brand and a Bloom Booster Flower Food contain a balanced mix of nutrients, including nitrogen, phosphorus, and potassium (NPK).

Conversely, Miracle-Gro is also a budget yet Water Soluble FERTILIZER knock-out roses fertilizer which, other than being a Bloom Booster Flower Food, is a popular choice for gardeners who want to promote healthy growth and vibrant blooms in their knock-out roses plants.

This fertilizer is specifically formulated to provide knock-out roses with the nutrients they need to produce big, beautiful blooms. It can be used on various flowering plants, as it does not stain or burn either roots or shoots of knock-out roses.

Lastly, unlike other fertilizer brands in our review Miracle-Gro knock-out roses fertilizer works with soil nutrients and pH levels as it is an all-purpose knock-out rose organic fertilizer.

View on Amazon

3.Espoma Rose-Tone 4 Lb Abundant Blooms Double Knock-out Roses 4-3-2 Organic Fertilizer Kit.

The third post on our review is Organic Rose-Tone from Espoma, the best NPK Organic Fertilizer for double-knock-out roses. It is a highly effective product for promoting the vegetative growth and blooming of all double knock-out roses and other flowering plants. Following that up, Espoma Rose-Tone, an organic fertilizer, contains a balanced blend of essential nutrients, including a 4-3-2 ratio of nitrogen, phosphorus, and potassium, vital for double knock-out rose’s healthy plant growth.

One of the standout features of this fertilizer is that it is made entirely from natural and organic materials, hence pet and kids-friendly.Moreover, by being an organic fertilizer for double knock-out roses, Espoma Rose-Tone does not deplete the ozone layer by releasing hydrocarbons into the ecosystem.

In retrospect, by having 4-3-2 as the n.p.k fertilizer ratio, Espoma Rose-Tone has a gentle fertilizer formula that makes it safe to use on all types of plants, including double knock-out roses, without the risk of harming the soil or the environment.

In terms of application, Espoma Organic Rose-Tone is easy to use and apply to your plants. Furthermore, despite coming in a 4 lb. bag, this budget fertilizer option for double knock-out roses is enough to cover approximately 100 square feet every 4-6 weeks throughout the knock-out roses blooming or growing season for best results.

View on Amazon

4.J R Peters Inc 51024 Jacks Classic 10-30-20 double knock-out Roses Blossom Booster Fertilizer kit

Taking the fourth spot, find Jacks Classic from J R Peters Inc as the best fertilizer for indoor and outdoor double Knock-out roses in spring, as it has 10-30-20 as the n.p.k fertilizer ratio. Furthermore, we found it to be the most appropriate granular fertilizer to use When fertilizing Knock-out roses in spring as it has 10-30-20 on the product name, which refers to the fertilizer’s nutrient ratio, with 10% nitrogen, 30% phosphorus, and 20% potassium.

Due to this reason, Jacks Classic is also our best Best fertilizer for Knock-out roses in spring. That works with ® Rose ‘Radrazz’, a defined bright flower with deep red blooms in summer through spring seasons respectively.

Furthermore, you can also use fertilizer ® Rose ‘Radcon’, which is also known as Pink Knockout Rose, as the high nitrogen, phosphorus, and potassium are the main sponsors

Lastly, it is also multipurpose n.p.k fertilizer as you can also use it as a plant growth regulator, which can help promote bigger and more abundant double knock-out Roses blooms. It also has a high phosphorus content. As a result, it is a quality fertilizer brand for minimizing transplant shock in newly planted or transplanted double knock-out roses cutting or seedling.

View on Amazon

5.General Hydroponics Transplanting/ Starts 1-Gallon Double Knock-out Roses Seedlings Rapidstart Rooting Enhancer Complete Kit.

Next up is non-other than a 1 Gallon Rapidstart rooting enhancer from General Hydroponics as the best fertilizer alternative to using on Yellow Double Knock-out roses, sunny knock-out rose to coral knock-out roses to promote healthy yet beautiful bloom either in springs, indoors, in summer, in pots or even outdoors. Following that up by being pure and 100% natural vegan formulation, it helps produce chemical-free Double Knock Out roses bloom colors all season round without poising the environment.

Th organic nature of also is the treason as to why we found it to be the only fertilizer alternative e of petite knock-out rose care on our review today that is not only readily available but also decently priced as it only comes under $100 on amazon eBay, Walmart Pinterest, Reddit and home depot.

Furthermore, unlike other fertilizer brands in our review Double Knock Out roses roots stimulator from General Hydroponics is 100% Conceived from natural mineral and plant extracts. As a result, it improves soil structure

In retrospect by also an optimum double knock-out fertilizer alternative. Rapid start Rooting Enhancer also encourages the growth of beneficial microbial soil micro-organisms, which promote the formation of strong, reliable, disease free and pest-resistant roots system in both mature and newly planted double knock-out roses

View on Amazon

Best Fertilizer For Double Knockout Roses FAQs

When Should You Fertilize double knock-out Roses?

The best time to fertilize knock-out roses is in the early spring, just as the plants start to grow. This is the time when the plants are most in need of the nutrients provided by fertilizer, and applying it at this time can help give the plants a strong start and encourage healthy growth.

It’s also a good idea to apply a second application of fertilizer in the summer, during the active growing season, to provide the plants with a steady supply of nutrients as they continue to grow and produce flowers.

In the fall, you can give the plants an additional boost with a fertilizer high in potassium to help them prepare for winter.

How Do You Make A Double Knockout Rose Bushier?

Despite Double, knock-out roses being popular for gardeners, these plants can sometimes become leggy and lack the full, bushy shape that many gardeners desire.

To make a double knock-out rose bushier, you can try the following methods:

1. Prune the plant regularly to encourage new growth. Double knock-out roses are typically pruned in the early spring before new growth begins.
2. When pruning, remove any dead, damaged, or diseased branches and cut back the remaining branches by about a third to encourage new growth.
3. Provide the plant with adequate sunlight, water, and nutrients. Double knock-out roses need at least six hours of direct sunlight per day, and they should be watered regularly to keep the soil moist but not soggy. Fertilizing the plant with a well-balanced fertilizer can also help promote healthy growth and make the plant bushier.
4. Pinch the stems of the plant to encourage branching. When the plant is young, you can pinch the tips of the stems to encourage the plant to produce more branches. This will result in a fuller, bushier plant.
5. Use a support structure, such as a trellis or stake, to help the plant grow upright and prevent it from becoming too leggy. This will help the plant grow in a more compact, bushy shape.

Following these steps can help your double knock-out rose to grow into a fuller, bushier plant.

How Do You Keep Double Knockout Roses Blooming?

Like all plants, they need proper care and attention to keep them blooming throughout the growing season. To keep double knock-out roses blooming, you can try the following methods:

1. Prune the plant regularly to encourage new growth. Double knock-out roses are typically pruned in the early spring before new growth begins. When pruning, remove any dead, damaged, or diseased branches and cut back the remaining branches by about a third to encourage new growth. This will help the plant produce more flowers.
2. Provide the plant with adequate sunlight, water, and nutrients. Double knock-out roses need at least six hours of direct sunlight per day, and they should be watered regularly to keep the soil moist but not soggy. Fertilizing the plant with a well-balanced fertilizer that contains a mix of nitrogen, phosphorus, and potassium (NPK) can also help promote healthy growth and encourage the plant to produce more flowers.
3. Remove spent flowers to encourage the plant to produce more blooms. Double knock-out roses typically produce flowers in flushes, and deadheading (removing spent flowers) can encourage the plant to produce more blooms. This is especially important in the fall, as removing spent flowers can help the plant focus its energy on producing flowers for the next growing season.
4. Provide the plant with adequate moisture during the growing season. Double knock-out roses are drought-tolerant plants, but they will produce more flowers if they receive adequate moisture during the active growing season. Water the plants deeply and regularly, especially during dry spells, to keep the soil moist and promote healthy growth and abundant blooms.

By following these steps, you can help your double knock-out roses produce more and longer-lasting blooms.

Wrap Up

After researching and considering various options, our editors have determined that the best fertilizers for double knock-out roses are General Hydroponics Rapidstart Rooting Enhancer and Jobe’s 09426 Granular, And Jobe’s Organics 09026.

These fertilizers have been proven effective at promoting healthy growth and vibrant blooms in double-knock-out roses. Additionally, they are easy to apply and provide a balanced blend of essential nutrients to support overall plant health.

We highly recommend giving these fertilizers a try for your double knock-out roses.