Best Slow Release Fertilizer For Flowers of 2024: Top 6 Picks

By Harry RamosLast update: 2024-07-11

Normally, flowers require a certain amount of nutrients for perfect blooms, but busy people don't have time to take care of them regularly. Let the best slow release fertilizer for flowers help you.

Why should you choose slow fertilizer instead of others?

You should choose one of the slow fertilizers here if you don't have time to fertilize your flowers often because it will release its nutrients slowly. You don't have to reapply within 6 months, or even one year. Just apply one time and let everything for the fertilizer.

Here are the best slow release fertilizers for flowers you can buy in 2024:

  • Best For Root Growth (Granular Fertilizer): Osmocote
  • Best For Vibrant Orchids (Granular Fertilizer): The Grow Co
  • Best For Dahlias (Granular Fertilizer): Dr. Earth
  • Best For Indoor Flowers (Fertilizer Spikes): Miracle-Gro
  • Best For Hydrangeas (Fertilizer Spikes): Jobe’s
  • Best For Rose (Fertilizer Spikes): Jobe’s for Abundant Roses
6 Best Slow Release Fertilizers For Flowers
Best For Root Growth
Osmocote
  • Granular Fertilizer
Best For Vibrant Orchids
The Grow Co
  • Granular Fertilizer
Best For Dahlias
Dr. Earth
  • Granular Fertilizer
Best For Indoor Flowers
Miracle-Gro
  • Fertilizer Spikes
Best For Hydrangeas
Jobe’s
  • Fertilizer Spikes
Best For Rose
Jobe’s for Abundant Roses
  • Fertilizer Spikes

Best For Root Growth: Osmocote

Pros
  • Convenient and easy to use
  • Long-lasting
Cons
  • Expensive

You are here to find a slow release fertilizer for flowers, so you might care about the percentage of phosphorus. The Osmocote Granular Fertilizer is great with P = 14. Besides, this product's nutrient ratio is 14-14-14 (N-P-K), so other nutrients are also high. K is high for a healthy root growth that is a great start for a complete development of your flowers.

Osmocote Specifications

Size

8 lb

Fertilizer Analysis

14-14-14

Highlight Features

Applicator included

Verdict

The Osmocote Granular Fertilizer is good for a complete development of your flowers because it can provide your plants with all nutrients in the same ratio.

Best For Vibrant Orchids: The Grow Co

The Grow Co
The Grow Co
Pros
  • Easy to use
  • Straightforward to follow the instruction
Cons
  • Hard to read the direction on the label - brown words

Unlike other kinds of flowers needing a percentage of phosphorus for blooming, orchids require a nitrate rich formula to produce bigger flowers. With the nutrient ratio of 3-1-3 (N-P-K), The Grow Co Granular Fertilizer can meet this requirement.

Magnesium plays an important role in orchid nutrition, so this fertilizer also has 12 Mg to produce chlorophyll for photosynthesis.

The Grow Co Specifications

Size

5 ounces

Fertilizer Analysis

13-4-14

Highlight Features

A balanced mix of macro and micronutrients

Verdict

The Grow Co Granular Fertilizer is designed for a complete development of vibrant orchids.

Best For Dahlias: Dr. Earth

Pros
  • Easy to use
  • Safe and efficient
Cons
  • Expensive

Like other flower fertilizers, this Dr. Earth Granular Fertilizer has a high ratio of phosphorus to promote blooming, so it works well for all flowers, including dahlias.

According to customers, this product resulted in a wonderful outcome when applying it on their dahlias. So, you can believe in their actual experience.

Dr. Earth Specifications

Size

4 lb

Fertilizer Analysis

3-9-4

Highlight Features

100% organic and natural ingredients

no GMOs, chicken manure or sewage sludge

Verdict

The Dr. Earth Granular Fertilizer can promote any kind of flower, especially dahlias to bloom effectively.

Best For Indoor Flowers: Miracle-Gro

Miracle-Gro
Miracle-Gro
Pros
  • Convenient to use
  • Easy to understand the direction
  • Safe
Cons
  • Hard to separate

Before buying fertilizers for your indoor flowers, remember that all indoor plants are grown in potting mix that has available many nutrients, so you shouldn't choose a fertilizer with a high ratio of nutrients for them.

Thanks to low NPK numbers, the Miracle-Gro Fertilizer Spikes are a more suitable solution because they are just packed with essential micronutrients for the growth of indoor flowers. Phosphorus is 12 that is higher than the ratio of N and K, so it can promote the growth of your indoor flowers.

Miracle-Gro Specifications

Size

24 spikes/ 1 pack

Fertilizer Analysis

6-12-6

Highlight Features

Filled with the micronutrients

Feed continuously for up to 2 months

Verdict

The Miracle-Gro Fertilizer Spikes can provide your indoor flowers with enough nutrients without overwhelming.

Best For Hydrangeas: Jobe’s

Pros
  • Straightforward to use - straightforward to push into the soil
  • Simple to apply
  • Fairy good instructions
Cons
  • Overpriced

The Jobe's fertilizer spikes are the best for hydrangeas because it contains nitrogen and phosphorus that are essential for a complete growth of hydrangeas. This product doesn't contain sulfur and ammonia that will damage hydrangea flowers. In sum, it is specially formulated with all essential nutrients for acid-loving plants like hydrangeas to reach healthy blooms and leaves.

Jobe’s Specifications

Size

10 spikes per 1 pack

Fertilizer Analysis

9-8-7

Highlight Features

Works well for all acid loving plants

No measuring, no mess, no smells and no overfeeding


Verdict

The Jobe’s Fertilizer Spikes are specially formulated for acid-loving plants like hydrangeas.

Best For Rose: Jobe’s for Abundant Roses

Pros
  • Effortless to use
  • Explicit instructions
  • Good price
Cons
  • Requires you to apply in the right time

Are you looking for a suitable fertilizer for your rose garden? We are not experts, so don't choose one at random. Instead, consider the Jobe’s Fertilizer Spikes that are specially formulated for roses.

It's very easy to apply, but this fertilizer can feed your plants for up to 8 weeks. Just remember to apply at the right time - early in spring and late summer for pretty blooms because this is a beginning for a new growth.

After applying, many customers said that their roses bloom more beautifully.

Jobe’s for Abundant Roses Specifications

Size

10 spikes / one pack

Fertilizer Analysis

12-16-12

Highlight Features

No measuring, no wasteful runoff, no mess, hazards and smells

Verdict

The Jobe’s Fertilizer Spikes for Abundant Roses provide your roses with the right nutrients at a proper ratio to bloom as beautifully as possible.

How To Choose The Best Slow Release Fertilizer For Flowers?

What Is The Best Fertilizer For Flowers?

Any fertilizer can supply plants with 3 elements:

  • Nitrogen (N) can promote the growth of lush foliage.
  • Phosphorus or Phosphate (P) promotes the formation of blooming and fruit
  • Potassium or Potash (K) develops healthy root systems.

You can easily check the nutrient ratio of NPK on the fertilizer packaging. For instance, a 10-10-10 fertilizer means that it contains 10% of nitrogen, 10% of phosphorus, and 10% of potassium.

For flowers, choose a fertilizer with a high percentage of phosphorus that plays an important role in blooming. Besides, potassium nutrient boosts a vigorous root system. This is a good start for healthy flowers.

Which Brands Make The Best Slow Release Fertilizer For Flowers?

Dr. Earth

Dr. Earth is famous for plant-friendly products thanks to the high-quality organic ingredients. Most of them work faster and exactly. If you need more reasons to invest in a Dr. Earth product, here are some:

Certification

All fertilizers of this brand are certified by different organizations such as the Organic Material Review Institute and National Organic Program.

High-quality ingredients

Their products' ingredients are organic, which are naturally rich in nutrients, so they contribute in creating healthy soil to grow healthy plants.

Besides, they also have beneficial microbes that can resist pests, frost, and diseases.

FAQs

How often should I apply slow-release fertilizer?

In general, the slow-release fertilizer works for months, so it’s okay to apply one per a growing season.

Should I fertilize when flowers are blooming?

No.

Should I fertilize flowers in extreme heat?

No.

How do I know if my flowers need fertilizer?

Any fertilizer provides your flowers with nitrogen, phosphorus, and potassium. Your flowers need fertilizer if they have the signs of lacking these things.

Yellow leaves are one sign of nitrogen deficiency.

If your plants turn into a dull and dark-green, even purple color, it is accumulating too much nitrates in the plant and lacking phosphorus.

In case you see small spots and large patches of discoloration on the leaves, they have a low content of potassium.

What happens if I put too much fertilizer on flowers?

If there is a crust of fertilizer on the soil surface, it means that your flowers are not absorbing minerals, resulting in a buildup on the surface of the soil.

When the lower leaves are yellowing and wilting, it is over-fertilized, over-watered, or lacks light.

Browning leaf tips and margins means your flowers do not absorb the water in the right way. The latter is the cause of over-fertilization.

The roots of your flowers are limp and browned or blackned, it is the sign of burning.

If your flowers fall too many leaves, you are watering your flowers improperly.

In case your flowers don’t blossom at the right time, there may be something wrong, for example, over-fertilizing.

Your flowers don’t grow or even develop slowly since they don’t have the right balance of nutrients to support the development and metabolism. These imbalance nutrients might come from 2 reasons: over-fertilizing or lacking important ingredients in fertilizer.

Conclusion

Why don't your flowers bloom beautifully although you applied the best slow release fertilizer for flowers? Perhaps this is one of the biggest mistakes when you use your fertilizer:

You skip the directions on the label. Remember that this place contains much important information to reach an effective outcome. For example, you can't get beautiful blooms if you apply fertilizers at the wrong time or application.


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