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Are Coffee Grounds Good For Crepe Myrtles? What to Know!

yellow and red crepe myrtles

There’s no doubt that crepe myrtles are beautiful trees with gorgeous flowers. What most do not know when it comes to crepe myrtles, though, is that to do well, the soil they are planted in must be very specific. For example, it can’t be too rich in nutrients and shouldn’t be too wet. Are coffee grounds good for crepe myrtles? Since coffee grounds are slightly acidic, using them to help crepe myrtles thrive in alkaline soil is perfect. Plus, coffee grounds provide several other excellent benefits for your crepe myrtles.

We have the answers to several more questions below, including the best fertilizer for crepe myrtles and how often to give them coffee grounds. It’s the real-world info you need if you love crepe myrtles and want yours to thrive!

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How Often Should You Give Coffee Grounds to Crepe Myrtles?

As a fertilizer, you should add coffee grounds to crepe myrtles when you give them other types of fertilizers. That is typically in the early spring, just before they start seeing new growth. For younger crepe myrtles, fertilization should be done lightly, once a month, throughout their first growing season. If your crepe myrtles are established, lightly fertilizing them about every two weeks until the end of summer is recommended. Remember to water your crepe myrtles well after giving them fertilizer, including coffee grounds.

dark pink crepe myrtle
Image Credit: imageseeker107, Pixabay

What Is the Best Fertilizer for Crepe Myrtles?

One suggestion plant experts have before fertilizing your crepe myrtle(s) is to perform a soil analysis. You can pick up a soil test kit at your local big-box home improvement store and do it yourself (which is usually cheaper and gives faster results). For alkaline soil, a general, all-purpose garden fertilizer is best: one that’s also well-balanced. Most experts recommend a 10-10-10 or an 8-8-8 fertilizer. These numbers represent the fertilizer’s nitrogen, phosphorous, and potassium.

When Should You Stop Fertilizing Crepe Myrtles?

Once fall begins, you should stop fertilizing your crepe myrtles and water them less frequently. This change allows the tree to “harden off,” which toughens the tree up for the coming winter cold. Hardening off helps the crepe myrtle to survive the colder, drier winter conditions while they are dormant. By the way, when they are dormant the winter is the best time of year to prune crepe myrtles.

How To Use Coffee Grounds as Fertilizer

Using coffee grounds as a fertilizer to help your plants couldn’t be easier. You can sprinkle a light coating of coffee grounds on top of the soil and let Mother Nature do the rest. You can also mix coffee grounds into the top 1 or 2 inches of soil if you like, but it’s not truly necessary. Experts recommend a thin coating of coffee grounds rather than a thick one as the grounds can easily be compressed. If they are, they will form a barrier preventing air and water from passing through your plants. Also, after putting down the coffee grounds, cover them with a thin layer of shredded bark, compost, or some other organic matter.

One of the best ways to use coffee grounds as fertilizer is to add it to your compost pile rather than directly into the soil where your plants are growing. If you do, be sure that no more than 20% of the total compost pile is made up of coffee grounds. If there’s more than that, the coffee grounds might inhibit microbes from breaking down the organic matter of the food scraps in your compost. You can throw your paper coffee filters into the compost, too, as long as you tear them into small pieces. (They add carbon to the mix!)

putting used coffee grounds on the plants
Image Credit: ThamKC, Shutterstock

What Do Coffee Grounds Do for Plants?

There are several benefits your plants, including crepe myrtles, will receive from coffee grounds, although some are yet to be proven by scientific testing. One thing coffee grounds do is add organic material and nitrogen to the soil. This extra organic material improves drainage for your plants while also improving water retention. Nitrogen is one of the three classic ingredients found in most plant fertilizers. It’s also been found that coffee grounds benefit microorganisms that help plants grow and thrive.

Coffee grounds have also been shown to decrease weed growth, which can be very helpful. They also protect your plants from snails and slugs since the slimy critters find the grounds too abrasive to crawl over. Some have even said coffee grounds are a great cat repellent, but more research needs to be done to determine if this is true. Lastly, coffee grounds are excellent for attracting earthworms, which are highly beneficial to the soil and plants.

Are Coffee Grounds Acidic?

Many DIY gardeners are under the false impression that coffee grounds are acidic, but the fact is that, on the pH scale, they are very close to neutral. The reason is that coffee grounds, which by definition have been used to brew coffee, have had their acidity washed away. How? By the brewing process! You see, the acid in coffee is water-soluble. When hot water is poured over fresh ground coffee beans to make fresh coffee, the acid is washed away into your coffee cup, mug, or to-go container. The leftover coffee grounds are thus pH neutral. They have a carbon to nitrogen (C/N) ratio of 20-to-1.

Which Plants Like Coffee Grounds?

Several plants and flowers like coffee grounds, most of which are plants that love acidic soil. They include hydrangeas, rhododendrons, lily of the valley, hollies, roses, and azaleas, among others. Some fruits and vegetables that get a kick out of coffee grounds include carrots, radishes, blueberries, and cabbage. Others include cranberries, gooseberries, parsley, peppers, wild strawberries, and potatoes.

woman holding a box of used coffee ground to use as compost in her garden
Image Credit: DGLimages, Shutterstock

Which Plants Do Not Like Coffee Grounds?

Just as there are plants that thrive when using coffee grounds, some aren’t big fans of used java. A partial list of the plants that don’t like coffee grounds includes lavender, orchids, rosemary, yucca, pothos, and tomatoes. One thing to remember is that using coffee grounds on seedlings and young plants is not recommended. Even if they are a species that likes coffee, wait until they are mature to add it to their soil.

Can Leftover Coffee Be Used to Water your Plants?

Yes, leftover brewed coffee that has cooled can be used to water your plants! As we know, coffee grounds are a nitrogen source, and so is brewed coffee. One caveat, however, is that you should not use coffee with sugar or milk. It must be straight coffee with nothing added, lest you attract insects like ants or create a stinky mess in your garden or plant pot. Also, if you like your coffee strong, you might want to dilute it first. Remember, while coffee grounds are not acidic, coffee certainly is. If you see your plant’s leaves start to turn yellow, cutting back on the coffee might be necessary.

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Final Thoughts

Are coffee grounds good for crepe myrtles? As we’ve seen today, they certainly are! Because of their high nitrogen content, coffee grounds are an excellent nitrogen source for crepe myrtles and many other plants. They also ward off bugs, aerate the soil, and help it hold water. Coffee grounds attract earthworms, too, which are fantastic for your crepe myrtles and any other plants you’re growing in your garden! You can even water your crepe myrtles with fresh-brewed, cold coffee for an extra nitrogen boost! We hope today’s information answered all your questions about crepe myrtles and coffee grounds!

You may also be interested in: Are Coffee Grounds Good for Flowers? What to Know!

Featured Image Credit: dae jeung kim, Pixabay


Kate MacDonnell

Kate is a lifelong coffee enthusiast and homebrewer who enjoys writing for coffee websites and sampling every kind of coffee known to man. She’s tried unusual coffees from all over the world and owns an unhealthy amount of coffee gear.

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