5 Best Fertilizers for Crepe Myrtle | How & When to Use

Crepe myrtles are easy-going trees that often thrive in poor-quality soil. When fertilizer is necessary, however, these trees respond best to balanced, low-concentration formulas.

While it rarely feels like the case, choosing the right fertilizer for any given plant species is pretty straightforward. The hardest part is sifting through the hundreds of formulas vying for your attention. 

That’s exactly why I’ve put together a list of the best fertilizers for crepe myrtles along with comprehensive details of how and when to use them so you can get the best from your crepe myrtles each and every year. 

So, rather than waste hours comparing various formulas, you can jump straight to using the best fertilizer for crepe myrtles and spend more time enjoying your garden!

Best Fertilizers for Crepe Myrtles

q? encoding=UTF8&ASIN=B01NALRUDD&Format= SL160 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=theyardandgar 20&language=en US
ir?t=theyardandgar 20&language=en US&l=li2&o=1&a=B01NALRUDD

Best Slow-Release Fertilizer

Miracle-Gro Shake ‘N Feed Plant Food 18-6-12

Perfect choice for getting your Crepe Myrtle fertilizing off to a flying start at the beginning of the growing season. Can also be used as an all-purpose feed for many other trees and shrubs. 

Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10

Best Fertilizer Spikes

Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10

Ideal for small or potted varieties or young Crepe Myrtle to support strong and vigorous root growth and protect against disease.

Scotts Flowering Tree & Shrub Plant Food 11-7-7

Best Top Dressing

Scotts Flowering Tree & Shrub Plant Food 11-7-7

Perfect choice for season-long Crepe Myrtle fertilizing that can also be used as an all-purpose feed for many other trees and shrubs.

Choosing the Best Fertilizer for Crepe Myrtles

When feeding crepe myrtles, I recommend starting with a tree and shrub formula with a balanced N-P-K ratio.

Slow-release, granular fertilizers are the best option for mature crepe myrtles with extensive root systems. But liquid fertilizers and spikes have a place too depending on the growing conditions and health of your particular variety.

N-P-K Ratio for Crepe Myrtles

Fertilizer consists of a range of nutrients. The three most important — known as macronutrients are nitrogen, phosphorus, and potassium — and are listed on fertilizer labels as something called an N-P-K ratio.

The N-P-K ratio is an easy way to tell how much of each macronutrient a fertilizer contains. For example, a 5-10-10 fertilizer contains 5% nitrogen, 10% phosphorus, and 10% potassium.

Crepe myrtles respond best to relatively balanced fertilizers, such as those labeled 10-10-10, 15-5-10, or 18-6-12.

Ideal Soil pH for Crepe Myrtles

Crepe myrtles prefer soil that is slightly acidic — typically anywhere between 6.0 and 6.5 on the pH scale. Some varieties of Crepe myrtle can flourish in a soil pH as low as 5.0 so make sure you research the type you have before amending your soil.

A material like sulfur or aluminum sulfate may be used to lower the soil’s pH and to add more acidity. Conversely, I recommend using garden lime to raise soil pH if you need to make it more alkaline. 

Whether your goal is to lower or raise the pH, the amendment is most effective when done before adding plants to the soil so always check soil pH with a soil test kit before you begin planting.

Granules Vs Liquid Fertilizer

The application method of your fertilizer type matters a great deal when it comes to how quickly the nutrients are released into the soil and how fast you want your trees to absorb nutrients.

Liquid Fertilizer

Liquid fertilizer is ideal for jump-starting your crepe myrtle with a heavy dose of nutrition! 

Liquid formulas are best used at the very start of the growing season to replace nutrients lost over winter. You can also apply liquid fertilizer around newly planted crepe myrtles or ailing trees and shrubs to aid in establishment or bolster vitality.

Slow-Release Granules

Slow-release granules are my preferred option for routine fertilization of crepe myrtles and many other ornamental trees. 

Granules are easy — and economical — to distribute over a large surface area. This is perfect for covering the wide expanse of a mature crepe myrtle’s entire root system.

Slow-release granules also help ensure that your crepe myrtle is receiving a steady stream of nutrients throughout the growing season. And it’s easy to taper off applications as winter dormancy nears.

Fertilizer Spikes

Fertilizer spikes won’t do any harm to a large and well-established crepe myrtle. However, because they distribute nutrients to such a small section of the root system, fertilizer spikes aren’t a very efficient option.

Save your fertilizer spikes for smaller container plantings, instead! 

Organic Fertilizer

Organic fertilizers are similar to synthetic formulas, in that they contain nitrogen, phosphorus, potassium, and other key nutrients. 

Rather than using chemical-based ingredients, however, they are made up of animal and plant-based compounds such as compost, manure, bone meal, and other natural materials. 

Overall organic fertilizers are much better for the environment, cause less harm to wildlife, and will not contaminate water sources. 

However, those that use organic fertilizers are intimately aware of the ‘natural’ odor that can accompany them and that can be highly attractive to pets. I’ll leave you to make your own mind up about your particular preferences.

Best Fertilizers for Crepe Myrtles

Now on to the most important part. Following extensive research, my own experiences and knowledge, and receiving feedback from peers and other gardening experts, I present my list of picks for the 5 best fertilizers for Crepe Myrtles.

Pros

  • Releases nutrients for up to 3 months
  • Includes natural microbe support
  • Formulated for use in the ground and containers

Cons

  • Can cause foliage burn 

Of course, this continuous-release formula from Miracle-Gro has everything your crepe myrtle needs to flourish. But what I love is that it also includes ingredients — kale, bone meal, earthworm castings, and more — that support the soil’s natural microbes.

The handy flip-top lid and handled container make fertilizing really simple and can be used both for ground-planted trees and shrubs and also those grown in containers. 

It’s a great product for Crepe myrtle as one dose at the beginning of the growing season will see you through for a good 3 months and no need to switch products mid-way through.

How To Use: Evenly distribute granules throughout your tree’s drip line. Water the area thoroughly. Avoid getting fertilizer on the trunk, branches, or foliage as excessive amounts of fertilizing can cause scorching or burn.

Pros

  • Ideal for flowering trees and acid-loving plants
  • Easy to use design
  • Can also be broken up and applied as a powder

Cons

  • Not ideal for large root systems

Miracle-Gro is a leading fertilizer brand with a reputation to match. There’s seemingly no end to the types of Miracle-Gro fertilizer available to choose from, and these spikes are specifically formulated for ornamental trees and shrubs (like your beloved crepe myrtle).

While spikes are a super convenient way to feed your crepe myrtles, I would reserve them for young or potted trees. The number of fertilizer spikes needed for a mature crepe myrtle could end up costing a small fortune!

How To Use: Place spikes at least 3 feet apart within the drip line of your crepe myrtle in the spring and fall for continuous fertilization. The included plastic cap makes it relatively easy to drive each spike into damp soil.

Pros

  • Delivers nutrients for up to 2 months
  • Can be applied by hand or with a spreader
  • Safe for a variety of landscape plants

Cons

  • May have a strong smell

This slow-release fertilizer from Scotts is a great choice for any ornamental tree or shrub, including crepe myrtles. Each application lasts for up to 2 months, so there’s no need to worry about constantly fertilizing your garden. 

Whilst the blend of N-P-K isn’t as balanced as some other fertilizers in my top pick, this stands out as one to use at the start of the growing season before buds are formed. You can always switch up to a formula with a higher concentrate of phosphorous to increase flowering potential.

This is a great feed for many other acid-loving plants. I’ve used it with success as a fertilizer for Azaleas and Hydrangeas. In all cases, I’ve seen an increase in the size and quantity of blooms year on year.

How To Use: Apply granules directly to the soil by shaking the bag or, if covering a larger area, using a drop or broadcast spreader. Scotts recommends raking the granules into the topsoil to improve absorption and prevent unwanted run-off.

Pros

  • Specially formulated for crepe myrtles
  • Delivers consistent nutrition for up to 4 months
  • Contains five different nitrogen sources

Cons

  • Time-consuming application method

Using a fertilizer formulated specifically for crepe myrtles helps take a lot of the stress out of feeding your landscape not to mention a weight off your mind. 

This Nelson Plant Food formula is a favorite for many professional growers and Crepe myrtle fanatics for its flower-boosting power and diverse nutrient sources. 

The only consideration for many users is its limited application for use other trees and shrubs and also the labor of love involved with administering it.

How To Use: Rather than using a broadcast spreader, apply this granular by punching holes into the soil. Holes should be placed every 24 inches within the tree’s drip line. Evenly distribute the recommended amount of fertilizer across the holes and water thoroughly.

Pros

  • Phosphorus content boosts flower production
  • Water-soluble formula
  • Delivers instant and slow-release nutrition

Cons

  • May contribute to environmental phosphorus run-off in some regions

Don’t let the N-P-K ratio fool you — this Carl Pool fertilizer is safe to use on your crepe myrtles. In fact, it’s specially formulated for them! The extremely high percentage of phosphorus helps stimulate lots of vibrant, healthy flowers from the first signs of bud-set.

Because of the high phosphorus content, I recommend testing your soil before use. And if you live in a high-risk area for phosphorus run-off, I suggest using this fertilizer for container plantings only.

How To Use: Dissolve the fertilizer in water at a rate of 1 tablespoon per gallon. Apply the solution by watering plants as usual. You can also apply this formula using a refillable hose-end attachment.

How to Fertilize Crepe Myrtles

According to the University of Georgia, newly planted crepe myrtles should be fed at a rate of 1 teaspoon per month for the first growing season. When planting, apply fertilizer around the perimeter of the root ball before covering it with soil and watering in.

For mature crepe myrtles, apply granular fertilizer with a nitrogen ratio of 10 or less at a rate of 1 pound per 100 square feet. Fertilizer with a nitrogen ratio over 10 should be applied at a rate of .5 pounds per 100 square feet. Apply fertilizer over the drip line area, avoiding direct contact with the tree’s trunk. 

Of course, the amount of fertilizer you use depends on the manufacturer’s instructions on the product you’ve bought and the size of your Crepe myrtle.

Over Fertilizing Crepe Myrtles

When it comes to fertilizing crepe myrtles, less is more. Over-fertilizing is one of the most common issues gardeners face when cultivating this plant.

The first sign of over-fertilization in crepe myrtles is an over-production of foliage. 

This may not seem like a problem at first. But it means less energy is available for the crepe myrtle to put out its trademark blossoms.

As with any plant species, you should use a soil test kit before fertilizing crepe myrtles. A basic soil analysis will help you target nutritional deficiencies and avoid the risk of potential over-fertilizing.

Fertilizing Crepe Myrtles in Pots or Containers

All types of fertilizer can be used on potted crepe myrtles — liquid, granular, spikes, synthetic or organic. As with in-ground trees, I prefer a slow-release formula or spikes that get to work over a prolonged period of time and avoid the risk of run-off.

Container plantings naturally need more fertilizer than their in-ground counterparts. 

The most important thing to remember about fertilizing potted crape myrtles is to cease feeding up to two months before the first frost date. Crepe myrtles go dormant in the winter and excess nutrients in the soil will do more harm than good.

Apply fertilizer each spring when your potted crepe myrtle first comes out of dormancy. Continue applications throughout the spring and summer per the directions of your chosen fertilizer.

When to Fertilize Crepe Myrtles

Young crepe myrtle trees should be fertilized at the time of planting and then several times throughout the first growing season — as often as once per month.

Established crepe myrtles benefit most from being fed first thing in early spring. Aim to apply fertilizer after pruning crepe myrtle but before the tree puts out new growth.

How Often to Feed Crepe Myrtles

Spring isn’t just the best time to fertilize mature crepe myrtles. It’s often the only time you should.

Some gardeners fertilize their crepe myrtles again in the fall. To prevent over-fertilization, this second feeding should only be done if a soil test shows nutritional deficiencies.

Verdict: Best Fertilizer for Crepe Myrtles

I’m a strong believer that fertilizer is a tool, not a miracle cure. So I encourage you to choose the best fertilizer for crepe myrtles based on the needs of your own landscape or garden as well as the size and health of your plants.

My number one choice for fertilizing Crepe Myrtles and getting their growing season underway successfully is to buy Miracle-Gro Shake N’ Feed Plant Food 18-6-12

Or, for smaller Crepe Myrtle or when growing in pots or containers, opt for the no-fuss, mess-free option that is Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10.

For a high-quality formula that caters to improving healthy soil pH and for caring for your Crepe myrtle’s nutritional needs all season long, I recommend Scotts Flowering Tree & Shrub Plant Food 11-7-7.

q? encoding=UTF8&ASIN=B01NALRUDD&Format= SL160 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=theyardandgar 20&language=en US
ir?t=theyardandgar 20&language=en US&l=li2&o=1&a=B01NALRUDD

Best Slow-Release Fertilizer

Miracle-Gro Shake ‘N Feed Plant Food 18-6-12

Perfect choice for getting your Crepe Myrtle fertilizing off to a flying start at the beginning of the growing season. Can also be used as an all-purpose feed for many other trees and shrubs. 

Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10

Best Fertilizer Spike

Miracle-Gro Tree & Shrub Plant Food Spikes 15-5-10

Ideal for small or potted varieties or young Crepe Myrtle to support strong and vigorous root growth and protect against disease.

Scotts Flowering Tree & Shrub Plant Food 11-7-7

Best Top Dressing

Scotts Flowering Tree & Shrub Plant Food 11-7-7

Perfect choice for helping to amend soil pH to enable season-long Crepe Myrtle fertilizing. Also suitable for use as an all-purpose feed for many other trees and shrubs.

FAQ’s Fertilizing Crepe Myrtle