Best Slow Release Fertilizer for Flowers and Shrubs

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In today’s post, I’m sharing my pick of the very best slow release fertilizer for flowers together with three other great options for shrubs and perennials. So, if you’re looking for the best slow release fertilizer you can buy, then you’ll love this article.

My research method involves personal experience with every product that I recommend or recommended by a tribe of the people I trust. Based on these criteria, I have ranked the best fertilizer options for everyday gardeners and plant enthusiasts.

I have focused largely on slow release fertilizers that are best suited to those who like to nourish their soil with vital micronutrients while taking care of the environment.

So, what are the main factors to consider when deciding the best slow-release fertilizer for you?

You should look at the formulation which includes NPK ratio and any additives used to enhance the fertilizer’s effectiveness such as micronutrients, kelp, or earthworm castings. You’ll also need to look at the mechanism of dissipation which is the degradation of the fertilizer granules in the environment.

Most gardeners use the terms slow release fertilizer interchangeably with controlled-release fertilizer. These are quite different products. While the slow-release fertilizer disintegrates completely into the soil with time, smart or controlled release fertilizers such as Osmocote contain plastic shells (resin) coated with the fertilizer which don’t degrade. This is likely to pose a threat to the environment in the long run.

Certain aspects might also be decisive depending on your plant’s stage of growth. 

For instance, if you don’t time your fertilizer application based on your plant's growth stage, you risk exposing them to burning. However, you don’t have to worry about this with slow release fertilizers.

You’ll also want to look at the prevailing temperature conditions and moisture availability. These two conditions often speed up microbial activity which means slow-release fertilizers can occasionally be released very quickly.

If this is the case, you need to select a fertilizer that will feed your plants for longer in most cases up to 3 months. It’s worth noting that not all slow release fertilizers take that long. Some will go for only 3 weeks.

Whatever your budget, expectations, or approach, this guide on the best slow release fertilizer for flowers, trees, and shrubs will feature the perfect option for you.

My outright pick at the moment is the Miracle-Gro shake 'N feed. A slow-release fertilizer that contains vital micronutrients plus added natural ingredients to nourish above and below the soil. The perfect choice for both avid and new gardeners, easy to use with visible results.

That’s not to say it’s the perfect fertilizer for you. Schultz Rose & Flower Slow-Release Plant Food, for instance, is a strong choice for rose shrubs and other acid-loving annuals.

While in my view Miracle-Gro Shake ‘N Feed is the best slow release fertilizer for flowers, trees, and shrubs, the list below covers other great alternatives that provide excellent value for money as well – so you can be sure you’ll find exactly the right continuous release fertilizer for you.


Best Slow Release Fertilizer for Flowers at a Glance

1. Miracle-Gro Shake 'N Feed Flowering Trees and Shrubs Plant Food (Best Overall)

2. Schultz Rose & Flower Slow-Release Plant Food (Runners Up)

3. Scotts Evergreen Flowering Tree & Shrub Plant Food (Best by Price)

4. Schultz Slow-Release Bloom Fertilizer


Best Slow Release Fertilizer for Flowers and Shrubs

1. Miracle-Gro Shake 'N Feed Flowering Trees and Shrubs Plant Food (Best Overall)

Miracle-Gro Shake 'N Feed Flowering Trees and Shrubs Plant Food has an NPK ratio of 12-4-8 and contains vital micronutrients. Besides, there are other natural ingredients included to help in nourishing the soil while improving the efficacy of the fertilizer.

The ingredients formulated include; kelp, earthworm castings, feather meal, bone meal. Although some people have reservations about bone meal because of the smell, the mixing has been done in ideal proportions so that they adequately feed microbes in the soil.

The symbiotic relationship between the organic matter, the microbes, and the fertilizer plays an important role in root development and nutrient uptake. You’ll be able to observe visible results in a matter of few weeks.

Miracle-Grow Shake ‘N feed is specifically designed for flowing trees, shrubs, and other acid-loving plants to maintain deep, lush green foliage and colorful blooms throughout the season. The application is easy and effortless and you can use this fertilizer in containers and outdoor thereby feeding your plants for up to three months.

You can be sure that your plants will love this fertilizer and, you will too.

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2. Schultz Rose & Flower Slow-Release Plant Food (Runners Up)

The one thing I love about Schultz Rose & Flower Slow-Release Plant Food is the fact that you won’t have to mix anything. The fertilizer is ready to use and you can just get on with the application. Besides, this slow-release fertilizer constitutes micronutrients which are essential to give your roses, perennials, and annuals fuller and healthy foliage.

Once you apply this fertilizer, it will feed your plants for up to 3 months after which it will integrate fully in the soil or potting mix. Therefore, you don’t have to worry about any form of pollution to the environment. Schultz plant food contains an NPK ratio of 15-5-15.

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3. Scotts Evergreen Flowering Tree & Shrub Plant Food (Best by Price)

With an NPK ratio of 11-7-7, Scotts Evergreen Flowering Tree & Shrub Plant Food will encourage vigorous root growth and lush foliage in trees and shrubs such as evergreens, dogwoods, hydrangeas, magnolias, and many other acid-loving trees and shrubs like azaleas, camellias, and rhododendrons.

It’s easy to apply this fertilizer. To this, spread by hand or mechanical spreader over the surface of the soil around trees and shrubs. This method is quick, easy, inexpensive, and recent studies have shown it’s as effective in supplying nutrients to plant roots as other techniques.

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4. Schultz Slow-Release Bloom Fertilizer

Schultz Slow-Release Bloom Fertilizer is the last on this list but one of the best slow release fertilizer for flowers and other perennials. It’s also very easy to use since no mixing is required on your part. With an NPK ratio of 12-24-12, it’s heavy on phosphorous which is essential in flowering and fruit formation.

Keep in mind that the duration of nutrient release of this type of continuous release fertilizers mainly depends on soil microbial activity that is driven by soil moisture and temperature. This means you don’t have to worry about the fertilizer burning your plants.

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Conclusion

You’ve just read the best slow release fertilizer for flowers, shrubs, trees, perennials, and other acid-loving plants. So, which one should you buy?

Here’s our verdict:

Miracle-Gro Shake 'N Feed Flowering Trees and Shrubs Plant Food (Best Overall)

Schultz Rose & Flower Slow-Release Plant Food (Runners Up)

To summarize, the application of slow-release forms of nitrogen provides the most efficient use of this nutrient because root growth and nutrient absorption can occur anytime soil temperatures are above 40° F.

Also, crop nutrient requirements follow a dynamic pattern - they begin low in the early growth stage, increase sharply in the middle stage, and decrease in the late stage. Slow-release fertilizers follow a similar pattern.

Besides, slow-release nitrogen fertilizers are preferred over quick-release water-soluble fertilizers because they provide nitrogen more slowly resulting in more uniform growth. They also have a lower potential impact on the environment.

Pro Tip: Always remember that proper nutrient management should include the "Four R's" of fertilizer use: apply the right nutrient, at the right rate, at the right time, and in the right place for the selected crop and you’ll get the best plant growth ever.

As always let’s know your thoughts in the comments.