Best Fertilizer For Flowers (How To Get Bigger Blooms!)

Looking for lots of big, beautiful flower blooms this summer? The right flower fertilizer can make all the difference. Learn about the best fertilizer for flowers + how to get hundreds of big, bold blooms all summer long right here!

orange marigold flowers that have been fertilized

Vibrant, colorful flowers are the highlight of the summer flower garden.  But throughout the growing season plants use up the available nutrients in the soil as they pump out their gorgeous blooms.

If you expect your flowering plants to keep producing, they need flower food!   Organic fertilizers are the best way to ensure your flower beds get the nutrients they need in order to pump out gorgeous flowers all summer long.  

Today we’ll be sharing all about the best flower fertilizers.  You’ll learn how and when to use them, as well as the benefits of doing so!  

dr earth flower girl in front of yellow zinnia flowers

Best Fertilizers For Flowers

The best fertilizer for flowers contains a high amount phosphorous, which promotes blooms. Flower fertilizer should also contain nitrogen and potassium to promote overall plant growth.

These are our top recommended fertilizers for flowers.  Read the entire article to understand how and when to fertilize, and why certain fertilizers work better for flowers!

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Miracle Gro Flower Food

Featuring an NPK ratio of 15-30-30, we have used Miracle Gro flower food for decades with amazing results.  This liquid plant food is easy to apply: simply mix with water and soak the soil around the base of the plant.  

Odorless and easy, you can use this flower fertilizer on your annuals and perennials up to every two weeks. Begin applying Miracle Gro about thirty days after planting. Miracle Gro is the perfect choice for pushing out lots of flower buds.

Jack’s Classic Blossom Booster

This professional flower fertilizer has been around for 80 years, and packs a powerful punch in the flower garden.  Featuring a 1-3-2 NPK ratio, Jack’s blossom booster promotes big colorful blooms and works well with annual flowers.  Apply this liquid fertilizer every two weeks for best results.  

Dr Earth Flower Girl

Dr. Earth Flower Girl contains a “superior blend of fish bone meal, alfalfa meal, feather meal, soft rock phosphate and mined potassium sulfate”.  This bloom fertilizer features a healthy NPK ration of 3-9-4, and is well known for promoting flower blooms on dahlias, zinnias and petunias!

This organic fertilizer does have a slight scent and should be kept away from animals.  It is easy to apply, just work it into the soil!

We also recommend Dr. Earth’s fertilizer for the vegetable garden

Scott’s Rose + Bloom Granular Fertilizer

Featuring slow-release granules that can last up to 2 months, Scott’s Rose + Bloom is perfect for the busy gardener.  

This effective fertilizer can be used for container gardens, flower beds and around rose bushes.

A time-release fertilizer like Scott’s will give your flowers an initial boost of nutrients, then continue to support them for several months.  

Down To Earth Organic Rose + Flower Fertilizer

Down To Earth Rose and Flower fertilizer is a certified organic rose and flower fertilizer that is easy to apply and very effective. Featuring an NPK of 4-8-4, this special blend contains both bone meal and blood meal. It can be used on bulbs, perennials and annuals.

Fish Emulsion (Neptune Harvest)

If you are having trouble with overall plant health, fish fertilizer can really help.

In addition to promoting blooms, fish emulsion is one of the best ways to promote new leaf growth and encourage your flowers into full bloom.  This gentle, all purpose fertilizer comes in a liquid form and can be used on the vegetable garden as well.  

Bone Meal

Bone meal is a natural fertilizer that is full of minerals that support root growth and overall plant health.  

It contains calcium, phosphorous and nitrogen and gives a gentle boost for your plants, especially useful for young flowers. This easy to use fertilizer can simply be mixed into the soil at planting time. Use about 1 tablespoon of soil per annual plant.  

Keep reading to learn how and when to use fertilizers for flowers!

best fertilizer for flowers

Did you know? In addition to promoting flower blooms, a good quality flower fertilizer will support the plant’s stems and leaves and help protect it from disease!

What Is The N-P-K Ratio For Flowers?

The N-P-K ratio can be found on almost every fertilizer package. It stands for the nitrogen, phosphorous and potassium percentages available in each fertilizer.  These are the major nutrients in commercial fertilizers and each nutrient plays a specific role in plant growth.  

The right nutrients in your soil and fertilizer will promote lots of blooms AND keep your plants healthy and lush all season long.

How NPK affects your plants:

  • The first number stands for nitrogen.  Nitrogen supports the growth of leaves and foliage, adding to the vibrant green color in the leaves and stems.  It is one of the main nutrients that supports a lush, strong plant.  
  • Phosphorous encourages bloom production and growth, helps fight disease and encourage strong roots.  
  • Potassium keeps roots healthy, helps flowers to form and helps protect against pests and disease.

For best results when fertilizing flowers, choose a fertilizer with a phosphorous number that is twice as large the nitrogen number.  

yellow zinnias

This will encourage the plant to put a lot of energy into the flower blooms, and not too much energy into the leaves and foliage!

Most flower fertilizers will have this number readily available, and it will help you determine whether or not that specific fertilizer will work well for plants.

Learn how to properly water flowers here!

What Fertilizer Makes Flowers Bloom?

Fertilizers with high amounts of phosphorous promote blooms.  As mentioned, the N-P-K ratio should feature a lower nitrogen level and higher levels of phosphorous and potassium.  

These essential nutrients will encourage lots of blooms throughout the season.   Too much nitrogen will promote foliage growth instead of flower blooms.

orange marigolds

You can choose liquid or granular fertilizers, both will get the job done. Do not use both however, and do not over fertilize!

A slow release fertilizer breaks down over time and does not need to be applied as often.  A liquid fertilizer gets the nutrients into the soil quickly but needs to be applied regularly using a watering can or hose attachment.

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Always follow the instructions on your chosen flower fertilizer.  Do not give your flowers too much fertilizer, or they can be burned by the chemicals, causing wilted yellow leaves and lack of growth.

In addition to a good flower fertilizer, make sure the soil is rich in organic matter and well draining- both of these aspects will affect flower bloom!

​Did you know dahlias are heavy feeders?  Learn how to fertilize dahlias here! 

Gardener’s Tip: Before fertilizing in flower beds, do a soil test! This test will tell you about the soil pH and nutrient make up in your soil. From here you can amend your soil with organic material and fertilizers. You can adjust your soil best on your test results, which gives better nutrition for your plants.

yellow sunflower with green leaves

What Flowers Should I Fertilize?

Almost all annual flowers can be fertilized, including plants like petunias, marigolds, zinnias, calibrachoa, and Sunfinity sunflowers. Annuals are continually pumping out blooms throughout the growing season, so they need the support of commercial fertilizers.  

Many perennial flowers, such as peonies and roses, need to be supported with a quality fertilizer and well draining, fertile soil.

orange marigolds growing with fertilizer

Some flowers, like dahlias, are heavy feeders and need more attention given to soil quality and fertilizer.

There are a few outlying annuals that do NOT need to be fertilized, such as cosmos.  When cosmos are fertilized they tend to put effort into growing foliage at the expense of blooms. And many drought tolerant perennials, such as lavender and salvia, actually thrive without fertilizer application.

Additionally, there are many acid-loving plants that thrive with specific fertilizers such as azaleas, rhododendrons, and camellias.

The best thing to do is to gain an understanding of each type of flower or shrub and give them the fertilizer they need at the time of planting.  Continue to support your flowers as needed with the specific kind of fertilizer they love best.

When To Fertilize Flowers

The best time to fertilize flowers is at the beginning of the season or when planting, and then at two week intervals throughout the growing season.  

Many annual flowers, like petunias, pump out hundreds of flowers throughout the season. They need the regular support of flower fertilizer to continue to push new growth.  This is especially true when growing them in pots and containers, as the soil within the pot is quickly drained of nutrients.  

Other flowers, such as peonies, bloom just once during the season.  These flowers do not need to be fertilized throughout the summer season but instead should be given fertilizer at specific times to support their blooming cycle. 

Make sure to pay attention to your soil type before planting.  All the fertilizer in the world will not do your plants any good if they are being planted in heavy clay soils or sandy soil that lacks nutrients!

How To Fertilize Flowers

The first step in fertilizing flowers is understanding what kind of plants you have!

Keep in mind that there are both general fertilizers and fertilizers created for specific plants.
Generally speaking, annuals that are bought and planted together can all receive the general bloom food. 

It is a good idea to approach flowering shrubs as separate plants that need to be fertilized. This is because flowering bushes and shrubs often have different fertilizer needs than annuals.

yellow sunflower that has been fertilized

Plants like azaleas and rhododendrons will need a fertilizer that caters to their love of an acidic soil.  They also need to be fertilized earlier in the year.  

Additionally, many low maintenance plants that love dry, sandy soil may not need to be fertilized at all (like French lavender!).

Take a good look at your garden beds and do an inventory of the flowering plants that you have.  Do a little research before fertilizing so that you choose the right fertilizer for each plant.

Make sure to follow the instructions for applying your fertilizer, a little often goes a long way! A high concentration of fertilizer can burn a plant, so be careful to apply your fertilizer correctly. Usually this means that you will dilute a tablespoon or two of fertilizer into a gallon of water. 

Best Fertilizer For Flowers In Pots + Containers

Container plants use up their nutrients quickly and will need to be fertilized.  There is a limited amount of nutrients in the soil within the container, and once these nutrients are used up, the soil quality quickly becomes poor.  

marigolds that have been fertilized recently

In order to combat the nutrient loss, fertilize potted flowers regularly.  This will encourage them to stay healthy and keep producing beautiful blooms all summer long.

Both liquid and granular fertilizer can be a good choice for potted flowers.  

We have often used Miracle Gro Bloom Booster for our flowers in pots and containers.  We have seen awesome results in both plant health and consistent, huge flower blooms.  

Making sure to fertilize your plants growing in pots and containers will make a huge difference in how many blooms your flower produces and how big they grow.  For big, colorful blooms be sure to fertilize potted plants regularly.

FAQ’s On Flower Fertilizer

What is the best N-P-K for flower blooms?

The best N-P-K ratio for flowers is a ratio where the phosphorous level is double the number of the potassium and nitrogen, such as 10-20-10 or 5-10-5. The phosphorous will promote plant bloom.

What natural fertilizer makes flowers bloom?

Fertilizers high in phosphorous will encourage bloom growth.

What is the best fertilizer for annuals?

Both slow release and liquid fertilizers can benefit annuals. If using a liquid fertilizer, be sure to reapply it every few weeks. The best fertilizers for annual flowers will have a high phosphorous ratio in relation to nitrogen and potassium.

Check out our web story on fertilizing flowers here!

Final Thoughts

A backyard full of colorful flowers is every gardener’s goal!  But plants expend a lot of energy pumping out those gorgeous flowers all summer, and they need to be supported with a good fertilizer.

Before you reach for the all purpose plant food, however, take some time to understand your flower’s needs.  

Most flowers will bloom best with a phosphorous rich fertilizer featuring natural ingredients. Either fertilizer granules and liquid fertilizer can be used, the trick is to be consistent and to apply the fertilizer properly.

Giving your plants the fertilizer they crave will ensure abundant, full blooms all summer long!  

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