Coffee grounds are one of those waste products that we, as gardeners, should covet for their nutritional benefits. This waste product contains a high level of nitrogen as well as some potassium and phosphorus.
Although not all plants will immediately love the grounds if you apply them directly to the soil, there are others that will adore them. Generally speaking, most coffee grounds are a little acidic in nature, so acid loving plants will benefit the most.
To help you understand how to use coffee grounds in the garden, here are 5 effective ways you can dispose of the remnants of your morning coffee.
*This website is reader-support so this post may contain affiliate links for which I earn commissions.*
1. Sprinkle Them Around Your Plants
Any plants that love more acidic soil will benefit from some used coffee grounds. Vegetables like tomatoes and cucumbers are particularly partial to an addition of grounds. You can just sprinkle the grounds directly on the soil around your plants.
After you’ve done this, you might want to rake the used grounds into the soil a little. The reason for this is that some grounds have very small particles. These particles can tightly clump together when they get wet. This could create a crust on your soil that repels water.
So, if your coffee remains are very finely ground, either rake them into the top layer of the soil or mix them with a little compost or even leaf litter. This effectively breaks up the tiny particles.
2. Add Them To Your Compost
Used coffee grounds are considered a “green waste” which is why they’re so good to add to your compost. They contain lots of nitrogen to enhance the fertilizer effect of a good compost.
After you add the grounds to the compost, make sure you mix them in. I have a compost tumbler, which I love. Every time I add some waste material to it, I give it a few spins. This ensures that air is incorporated into the waste as well. In turn, this helps to break down the contents much faster.
By the way, if your coffee machine uses paper filters, you can add these to the compost as well.
3. Use Them To Make A Fertilizer “Tea”
We all know that liquid fertilizer will act much faster than any other type. In a liquid form, the nutrients are easily taken up by the plant roots to use as food.
To make your liquid fertilizer, follow these steps:
- Fill a 5-gallon bucket or watering can with water.
- Add around 2 cups of used coffee grounds.
- Give the concoction a stir and let it sit for a few hours. Overnight is best.
- Water your vegetables with this mixture and watch them grow.
4. Add Them To Your Worm Farm
Guess what? Worms absolutely love coffee grounds. So, add a cup of used coffee grounds to your worm farm around once a week. Don’t overdo it though. Too much acidity is not good for the worms either.
Another benefit of this is that coffee grounds in the soil, will actually attract worms to your garden. The worms will eat the grounds and leave behind nutritious castings that your plants will love.
5. Add Them To Your Potted Vegetables
Are you growing vegetables in pots? You can give them a boost by emptying the contents of your daily coffee grounds directly into the pot. I’ve done this very successfully with some tomatoes that I’m growing in pots.
After you add the grounds, water deeply so that the ground get down into the soil. Then each time you water, the used grounds will release their nutrients for the plants to use. You’ve just made your own slow-release fertilizer!
Bonus Tip: Use Them To Turn Your Hydrangeas Blue
I haven’t grown hydrangeas for years but moved into a house early in 2020 that had a couple of small hydrangea bushes growing next to each other. Now I had remembered from years ago, that the acidity of the soil determined the color of the flowers.
So, I decided to do a small test. I emptied the contents of my daily grounds onto the soil of one of the bushes. Then, the following day, I could see the flowers of that particular bush already starting to turn blue. And, over the progression of a few days, the flowers intensified their blue coloring.
Aha, I thought. So, to turn a hydrangea blue, you need a more acidic soil. Now, I could of course have Googled this and found the answer. But, as a gardener, it’s so much more fun to do these little tests instead.
Here’s a photo of my two small hydrangeas. The one on the right is the recipient of the coffee grounds. I did this experiment quite a few weeks ago, but the flowers are still slightly blue.
I’ve definitely fallen in love with these plants again. The flowers last an amazingly long time and they’re great as cut flowers. I’m currently in the process of propagating some new plants from these and will explain how to do this in another article.
Are There Any Don’ts With Using Coffee Grounds?
There are a few controversies around about the benefits of coffee grounds that I’ll list below. But remember, gardening is not an exact science. That’s what I love about it. You can test various things without it costing you a lot of money.
I’m always doing little tests to see what works and what doesn’t. I’ll share the more pertinent ones with you in future articles. So, what things should you be conscious of when using coffee grounds in your garden?
- Caffeine can inhibit the growth of other plants. But, we don’t actually know how much caffeine remains in the used grounds. It might be wise however, not to use grounds around seeds or young seedlings.
- Some people say that coffee grounds will deter slugs, snails and ants. However, even though these pests may not like the texture of the grounds, it’s unlikely that this is an effective deterrent.
- Coffee grounds may be harmful to dogs if they consume large amounts. Therefore, if your pooch likes to eat any scraps he or she can get hold of, bury your grounds instead of leaving them on top of the soil.
Want to know more about all the ways that you can use coffee grounds in your garden? Have a look at these articles:
Does Lavender Like Coffee Grounds: Which Plants Do?
Are Coffee Grounds Good For Tomato Plants? How To Use
Do Roses Like Coffee Grounds? Are They Good To Use?
Do Begonias Like Coffee Grounds? Best Way To Use Them
Frequently Asked Questions
Plants that prefer more alkaline soil will not appreciate coffee grounds being added. These include lavender, rosemary and geraniums.
The problem with just putting coffee grounds on top of the soil is that the grounds will compact and form a crust that won’t allow water through. It’s far better to either dig them in a little or mix them with some compost before applying them to your acid-loving plants.
Ants don’t like coffee grounds so these make a good natural deterrent. Just sprinkle dried grounds around the places where ants hang out in your garden and they’ll soon move on.
Final Thoughts
Used coffee grounds are beneficial for your garden, so don’t toss them away. I’ve given you 5 different ways to use coffee grounds in the garden. These can be beneficial to many different plants but should always be used sparingly.
My number one tip is and always has been, to add them to your compost bin. Since I’ve been adding them to my compost on a weekly basis, I’ve discovered that this has attracted a proliferation of earthworms to my compost.
Once the compost is ready, it and the earthworms get added to my garden beds to enrich the soil and provide my plants with all the nutrients that they need.
