7 Best Flower Fertilizers for Blooming Plants | How to apply

Have you ever had plants that didn’t bloom the way you expected them to? They look so pretty in the catalogs, so naturally, you’re expecting that same picture-perfect display of blooms in your own garden. Only to have it sputter and struggle.

What’s causing your plants not to bloom?

Here, I’ll explain all the reasons why your plants aren’t performing as expected. And what can be done to correct that?

Reason #1, if nutrient availability is sparse, buds won’t develop. A quick fix: make sure you have the best flower fertilizer.

Best Flower Fertilizers 

For effective ways to increase blooms and color on healthy plants, be sure to read all the way to the bottom for my complete list of top-performing fertilizers. If you just need quick, reliable advice for the best flower fertilizer, here are my two top picks.

Down to Earth Organic Bone Meal Fertilizer 3-15-0

Best Organic Fertilizer

Down to Earth Organic Bone Meal Fertilizer 3-15-0

Phosphorus-rich for maximizing flower bud formation. A completely organic, slow-releasing, bone meal option that provides nutrients for up to four months. 

Jack’s Classic Blossom Booster Fertilizer 10-30-20

Best Water-Soluble Fertilizer

Jack’s Classic Blossom Booster Fertilizer 10-30-20

A uniquely designed water-soluble bloom boosting formula for flower growing in less-than-desirable soil. Quickly adds an infusion of nutrients to improve soil and increase bloom time.

Jobe’s Organic Rose & Flower Fertilizer Spikes 3-5-3

Best Fertilizer Spikes

Jobe’s Organic Rose & Flower Fertilizer Spikes 3-5-3

A quick, easy, and mess-free way to improve the condition of soil while also ensuring the right NPK ratio for vibrant and abundant blooms plus healthy foliage.

What Nutrients Help Flowers Bloom? 

Studies have shown that plants know what season it is based on how much sunlight they detect. An increase, or decrease, triggers enzymes and proteins to ramp up or slow down growth and bud production. 

Weather conditions, ambient temperature, and the amount of accessible sunlight will also affect how well flowering plants perform. 

Even if all these factors are perfect, though, plants will produce very few blooms without access to vital nutrients. 

All plants require nitrogen, phosphorus, and potassium to thrive and bloom. Yet, phosphorus is what drives bud formation, fruit, and seeds. Which is the primary goal in a flowering plant’s reproductive process. 

N-P-K Ratio for Flower Development 

Flowering plants benefit from an NPK ratio that’s higher in phosphorus and potassium than nitrogen. But when they benefit depends on whether they’re ornamentals or fruiting plants.

With ornamentals (and some vegetables) one NPK ratio, throughout the season, is sufficient. A ratio of roughly 1:3:2, representing nitrogen, phosphorus, and potassium percentages, in that order.

Fruiting plants require more of one nutrient than another at different stages of development. Fruiting trees, berry bushes, melons, and squash perform best when given more nitrogen to start. Then, switching to higher phosphorus and potassium as buds set. 

Effect of Soil pH 

Vegetables and most ornamentals thrive in a soil pH between 5.8 and 6.5. Fruit trees prefer a pH between 6.0 and 7.5. While berry bushes, hydrangeas, and azaleas perform better in a lower soil pH, between 4.0 and 5.0.

No matter the preference of each plant, it’s important to get it right. Why? When the pH is too low, nutrients become too mobile and are absorbed in excess of what plants need.

In pH that’s too high, the opposite happens. Nutrients become locked in the soil and unavailable to roots. 

Minerals 

Just as important as macronutrients (nitrogen, phosphorus, and potassium) in the health and vitality of plants, are minerals and trace elements (or secondary nutrients). Among these are iron, manganese, copper, and boron. 

Macronutrients can’t perform their jobs to maximum capacity without the help of their micronutrient counterparts. 

Minerals work with nitrogen to build the complex molecules necessary for structural components like leaves, stems, and roots.  A process that starts with creating the green chlorophyll cells that facilitate photosynthesis in plant foliage.

Minerals then aid phosphorus and potassium in the healthy and abundant bud, flower, fruit, and seed production. 

Types of Fertilizer for Flowers 

Four different fertilizer categories offer flexible options for various applications and gardening preferences. 

  • Quick Release – liquid/water-soluble options offer immediate uptake of nutrients. Resulting in accelerated plant improvement and growth. 
  • Slow Release – Concentrated granules and spikes offer a steady stream of nutrients over an extended period of time. With little risk of plant burn. 
  • Organic – made from minerals, plant material, and animal bi-products that contain natural, vital nutrients. Nourishing plants and improving soil fertility, simultaneously.
  • Inorganic – manufactured with minerals and chemicals, these can result in a quick boost of growth. But can also potentially contaminate soil and do little to increase fertility. 

Liquid Fertilizer 

Liquid fertilizers come in both concentrated liquid and water-soluble granule forms. These can be applied with a watering can or hose attachment, around your plants.

Liquids can also come in either organic or synthetic forms. Either way, nutrients are immediately conveyed to the root system through the soil. Some are also formulated to be used as foliar sprays, which can provide instant relief for yellow foliage. 

Controlled Release Granules 

Slow-releasing granules are very simple to use and can provide consistent, controlled nourishment for up to nine months, depending on the brand. And that means fewer applications and less work for you. These are also less likely to cause root burn or other plant damage.

Nutrients are released by warming soil temperatures. Soil microbes and fungi then consume these nutrients and convert them into a form that is easily absorbed by plants. 

Organic vs Synthetic Fertilizers 

Choosing between an organic or synthetic flower fertilizer is a simple matter of gardening style, application preference, and end-result expectation. 

Organics contain levels of nutrients similar to what plants receive in the wild. They can nourish your plants for longer while improving soil fertility with little risk of contamination.

Inorganics are mass-produced using minerals and synthetic chemicals. These can produce more lush foliage and a higher bloom count but can also potentially contaminate nearby water sources and soil. 

Flower Fertilizer Reviews 

Product testing and review research take time, effort, and money. For your convenience, I’ve done some extensive testing on several different blooming plants in my own garden, both edible and ornamental. Below are my picks for the top 7 best fertilizers to increase blooming on healthy plants. 

Pros

  • A readily available source of organic nutrients
  • Includes vital micronutrients for optimal plant health

Cons

  • May exhibit an earthy odor 

As I mentioned at the top of this article, this slow-releasing bone meal option lasts for up to four months. It’s one I feel really good about using around my flowering perennials and bulbs and is my pick for the best organic flower fertilizer.

These granules also performed really well in the flowering stage of my tomatoes, squash, and melons. Delivering a steady flow of phosphorus and calcium results in an abundance of blooms (and fruit) with outstanding color and size.

How To Use: New transplants – mix in 1-2 tbsp per hole, then water well. For established plants – side dress with 2-4 oz per month during the growing season.

Pros

  • Quick dilution for use with watering cans or hose attachments
  • Extends bloom time beyond expectation

Cons

  • Not recommended for plants growing in highly fertile soil 

Nobody’s soil is perfect, and no product seems to understand that better than this phosphorus-rich formula from Jack’s Classic. This water-soluble option will nourish flowers growing in everything from “moderately fertile soil” to “basically just dirt”.

This can be diluted to whatever strength you need and provided my plants with a fast infusion of nutrients, in the most effective ratio. Not only did I see healthy plants that produced a generous number of blooms, but an increased bloom time, as well.

How To Use: Mix 1 teaspoon per gallon of water (or more for further dilution) and apply to flowering plants once per week. 

Pros

  • Effective nutrition for roses and other flowering shrubs
  • Slow-releasing for longer feeding and fewer applications

Cons

  • Maybe at a slightly higher price point than other brands 

These spikes from Jobe’s are formulated to encourage luxurious roses. But, with an NPK that could benefit other bloomers, too. So, I tested this rose fertilizer spike on some rose varieties in my collection. As well as some peonies and lilacs.

I was impressed because they’re relatively small and easy to push into the loamy soil around both my potted and ground-planted specimens. The plant type didn’t seem to affect performance. The surprisingly large buds that formed told of lush beauty and fragrance to come.

How To Use: Insert this combination of healthy microbes and organic nutrients around roses and other blooming perennials every 4-6 weeks, beginning in spring when new growth sprouts.

Pros

  • All-natural source of organic phosphorus and nitrogen
  • Helps to loosen heavy, clay soil

Cons

  • Not recommended for plants that require potassium 

An alternative to Down-to-Earth’s offering, this similar, granulated formula from Espoma requires 10lbs per 100 sq ft. (instead of 2.5lbs per 100 sq ft.) but you only need to apply it once or twice per season, rather than every month. 

The natural phosphorus that this provides can’t be beaten for giving flowering plants what they need to produce abundant blooms. Especially if you’re an organic gardener. The NPK in this also offers just enough nitrogen to support healthy foliage growth.

How To Use: Apply 1 or 2 pounds depending upon the size of the shrub or tree. Apply 2 oz or one tablespoon per potted plant and work into the soil. 

Pros

  • Focus on robust root support for large, vibrant foliage and flowers
  • Versatile enough for ornamentals and vegetable

Cons

  • Not recommended for use on phosphorus-sensitive plants 

These water-soluble granules from Ferti-lome are formulated to focus on overall plant health. Promoting robust root development for more blooms and healthy foliage. 

The foliage on the plants I tested this on was huge and the contrasting vein color, on some, was just stunning against the vibrant color of the blooms.

I usually see some yellowing on my plants by mid-august, due to the heat. But, I didn’t own any of the plants I tested, because these are also formulated to increase tolerance to environmental stresses. 

How To Use: Mix 2 tablespoons into each gallon of water used. Then, repeat every 1-2 weeks during the growing season. 

Pros

  • Effective in both harsh and temperate climates
  • Extended bloom times on single-season bloomers

Cons

  • Frequent watering may be necessary to avoid root burn 

Scotts offers this water-soluble, phosphorus-rich formula that promises instant feeding while protecting against root burn when used as directed. I live in a region with a short growing season, so I have to start my flowering annuals indoors. 

Not only did this NPK produce brightly-colored, abundant blooms on my petunias, pansies, and nasturtiums but hastened maturity in these plants for a longer bloom time!

Of course, this NPK ratio will do the same for perennial, flowering shrubs and bulbs, as well.

How To Use: Pre-moisten soil prior to application. Then mix two teaspoons into each gallon of water used and water normally. Repeat every 7-14 days. 

Pros

  • Contains natural ingredients to feed microbes in the soil
  • Includes vital micronutrient

Cons

  • Not recommended for rich, fertile soil 

I found this granular option from Miracle-Gro, with its simple “shake and feed” application method, to work best in the semi-fertile to poor soil around my potted bloomers.

Each granule is formulated to be attractive to hungry soil microbes who then convert nutrients into a readily available form.

The color on my container combinations became more vibrant. As well as the veining and coloration in the foliage. I no longer saw browning around the edges of leaves. Which indicated a nutrient deficiency.

How To Use: Apply 1 tbsp per 1 sq ft evenly across the soil. Apply dry. Do not pre-mix with water. 

How to Fertilize Flowers 

Waiting to fertilize seedlings until they’re well established outside is key to their success. Tiny plants can be sensitive to fertilizer. 

Once they’re established, an NPK with a higher percentage of phosphorus will provide the right combination of nutrients for bountiful blooms and lush foliage. 

For flowering vegetables, a higher nitrogen NPK will encourage strong root growth and plant structure while young. Once buds set, more phosphorus will support healthy blooms and fruit.

For acid-loving bloomers, make sure your phosphorus-rich flower fertilizer has a bit of sulfur in it to maintain the right pH for them.  

When to Fertilize Flowering Plants 

When to fertilize flowering plants, whether they’re perennials, annuals, bulbs, or shrubs, will depend on the formula and application method of your fertilizer. 

Typically, slow-release granules and spikes are applied once in spring, as soon as the first new shoots begin to appear. Then, a second time (again depending on the brand) in either summer or fall.

Flowering perennials don’t require fertilizing in winter, while they’re dormant. Even if they’re winter-flowering varieties that only go partially dormant.  

Liquids should also be applied to start in spring and then repeated as the manufacturer recommends throughout the growing season. 

How Often to Apply Fertilizer 

How often to fertilize will differ between application methods. For example, Down to Earth’s fast-acting, the organic bone meal needs re-applying every 4 weeks. Versus Espoma’s slow-release formula, which only needs one application in spring and again in fall. 

Water-soluble options, like Jack’s Classic, should be applied every two weeks for consistent nourishment. As should MiracleGro’s BloomBooster formula. The frequency could be even higher for potted plants, due to water and nutrient leaching. 

Verdict: Best Fertilizer for Flowers 

Well, I believe the verdict is in! The most effective flower fertilizer for your bloomers will primarily depend on plant variety. 

Most will need a higher dose of phosphorus at some point, regardless of species. In which case, I recommend you reach for Down to Earth Organic Bone Meal.

Down to Earth Organic Bone Meal Fertilizer 3-15-0

Best Organic Fertilizer

Down to Earth Organic Bone Meal Fertilizer 3-15-0

Phosphorus-rich for maximizing flower bud formation. A completely organic, slow-releasing, bone meal option that provides nutrients for up to four months. 

Flowering vegetables will need more nitrogen to start as opposed to annual and perennial bloomers that benefit from a 1:3:2 NPK ratio throughout the entire growing season and that’s when Jack’s Classic Blossom Booster is a perfect choice. 

Jack’s Classic Blossom Booster Fertilizer 10-30-20

Best Water-Soluble Fertilizer

Jack’s Classic Blossom Booster Fertilizer 10-30-20

A uniquely designed water-soluble bloom boosting formula for flower growing in less-than-desirable soil. Quickly adds an infusion of nutrients to improve soil and increase bloom time.

For a no-fuss fertilizer approach, I recommend Jobe’s Organics Rose & Flower Fertilizer Spikes. Just insert them into the soil around your flowering plants for vibrant and long-lasting blooms and enriched soil.

Jobe’s Organic Rose & Flower Fertilizer Spikes 3-5-3

Best Fertilizer Spikes

Jobe’s Organic Rose & Flower Fertilizer Spikes 3-5-3

A quick, easy, and mess-free way to improve the condition of soil while also ensuring the right NPK ratio for vibrant and abundant blooms plus healthy foliage.

FAQs Flower Fertilizers