Should you use coffee grounds for hydrangeas

Should you use coffee grounds for hydrangeas

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Image by Elias Shariff Falla Mardini from Pixabay

Everybody wants what’s best for their hydrangea and it’s easy to see why. Hydrangeas are a timeless classic, a flowering shrub that indicates summer is really here. What with the blues, purples, pink, and white hues, you can make almost any color in your garden. But how can you take things just a step further and really bring your flowers to life?

Using coffee ground on hydrangeas

One way is using coffee grounds on hydrangeas. Hydrangeas are well known for their globular blooms and with rich soil you can even alter the colors you get. Coffee grounds are in fact one way to create soil that produces slightly more unusually colored blooms. But before you head out to get your favourite coffee grounds, it’s important to understand how the process works.

Get the right plant

How to change the color of hydrangeas
How to change the color of hydrangeas

The idea behind adding coffee grounds to your plant is not just to fertilize it but rather to change the pH level of the soil. And this is done to change the colors of the blooms. If you add coffee grounds you can naturally make your soil a bit more acidic and as a result, you can produce blue blooms. But this is only applicable to certain varieties. In particular, the mop head or the lacecap varieties, as well as certain paniculata varieties, can do well with coffee grounds.

Add the right coffee

Coffee grounds when added to the soil will create a more acidic pH which will help your flowers to produce blue blooms instead of pink or white. It does not specifically have to be coffee grounds. Many people add things like aluminum sulfate or eggshells in order to achieve the same effect. But if you have coffee lying around or do you prefer to go a more natural route, coffee makes for a wonderful alternative. But bear in mind that if you use coffee to change the acidity of your soil it’s something you’ll have to do regularly. All hydrangea blooms will respond to an increased acidity in the soil but you need to make sure that you do it regularly and that the soil is still fertile and moist.

Changing the acidity

When you get ready to add coffee to your hydrangea, you need to start by testing the soil pH that already exists. Purchase an at home soil test kit. These can be found at home improvement stores or garden stores. Test the levels that you already have so that you know where you need to aim. If you have incredibly alkaline soil, it’s going to take a lot of effort to produce even the slightest blue color. If you have someone neutral soil, it won’t take much. Once you have your test results change your soil with coffee grounds by digging it into the soil. It is faster to just throw the coffee grounds on top of the soil but it’s going to smell a bit unpleasantly and leave your garden looking quite ugly as it starts to mold. It is better to work it into the soil. You can also long-term integrate the coffee grounds into your compost if you have a compost bin and then use that compost as part of your twice and you will fertilizing routine. This will help to naturally fertilize every 6 months.

After you have added the coffee grounds by digging into the soil, maybe even tossing it on top, you should keep testing the soil acidity to make sure that it’s where you want it to be. Bear in mind that your soil will naturally return to its original state so adding it into your fertilizer through your compost bin is a great way to change the soil composition long-term. As soon as you stop adding the coffee grounds for any length of time the flowers will go back to their original color.

Also important to note is that if you purchase hydrangeas from a store, they might already have a slightly blue flower but that does not mean that you will get blue flowers in your garden. The color you see in a nursery or garden store is reflective upon the soil pH levels of that container. Once you transport it to your home and transplanted into your garden or your container, whatever levels you have will naturally change the flowers. So you might have blue flowers when you first purchase your hydrangea but with time they’ll turn to pink at which point you should start considering the integration of coffee grounds.


So how quickly will you get results? Well, it isn’t a very fast process. It’s obviously faster, as mentioned if you simply toss the coffee grounds on top but then they start to mold in plain view. Some hydrangea plants will grow flowers on last years growth while others grow their flowers on the current growth. Flower buds will start to develop on hydrangeas once they are two or three years old depending on the species you have. So if you add coffee grounds to your soil, the earlier you add them, the sooner you will get changes in color assuming that the plant you have is old enough to produce blooms. Most buds will start to develop in the winter and then continue to develop throughout the spring such that they produce beautiful flowers at the end of summer and the beginning of fall. Again the sooner you add your coffee grounds, the sooner you can impact the growth of the buds.

Final notes

Coffee grounds will not only help you to change the acidity and therefore the color of your flowers but they are very helpful in moisture retention. So even if you don’t want to change the colors you can add a decent amount of coffee grounds to help your flowers absorb moisture better especially if you live in a dry area. Most hydrangeas will thrive with deep weekly waterings as opposed to lighter daily waterings and if you have coffee grounds in the soil it will keep the soil moist in between one watering and the next.

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