Being the coffee-loving, penny-pinching gardener that I am, when I heard that some people put coffee grounds in their peace lily plants, I wanted to give it a try. But I was frustrated by all the conflicting information I found- it seemed that there was no firm answer on how or even whether to use coffee grounds. So I decided to try it out for myself!
Do peace lilies like coffee grounds? Yes, coffee grounds can be beneficial to a peace lily, but only if they’re used in the right way. Making a weak coffee solution, mixing a small amount of used grounds into standard potting soil or adding coffee grounds to the compost bin are all effective strategies.
In this article, I’ll walk you through my experience and show you how my peace lily responded to coffee fertilizer. I also asked some other expert gardeners for their input on other safe methods for applying coffee grounds and just what it is about coffee grounds that give your plant a boost.
Let’s get started!
Table of Contents
Are Coffee Grounds Good for Peace Lilies?
As I mentioned earlier, there are a lot of conflicting opinions out there. After all my research and experimentation, my conclusion is that coffee grounds are a good addition to your peace lily care routine, provided you use them appropriately.
Now, what exactly is it that makes coffee grounds good for peace lilies? Let’s find out:
Acts as a Mild Fertilizer
Coffee grounds are a good source of several key nutrients, making them a good homemade fertilizer for peace lily plants. According to Healthline, coffee grounds contain:
While they’re all important, the one we’re most interested in is nitrogen. That’s what gives our peace lilies their gorgeous deep-green color and allows them to produce plenty of energy for new growth through photosynthesis.
Helps Soil Retain Moisture
Have you ever noticed how coffee grounds stay moist even if you leave them in the coffee maker for a day or two? Maybe you’re better at promptly removing spent grounds than me- in that case, you can take my word for it that they do!
Since coffee grounds naturally retain moisture, they’re an ideal soil amendment for plants that love consistently moist soil- like peace lilies.
Encourage Healthy Leaf Production
When I was doing my own reading up on coffee grounds for peace lily plants, I saw quite a few people say that coffee can reverse leaf browning.
Well, that’s true- but maybe not in the way you think.
Once a leaf begins to turn yellow or brown, it’s already dying and will never turn green again. But coffee grounds can help reverse the soil problems that caused the leaves to turn brown/yellow in the first place. Then, new healthy leaves can sprout in place of those discolored, dying ones.
May Repel Certain Pests
Caffeine is fatal to soft-bodies pests like slugs and snails, so coffee grounds can be a great natural pest control.
This is primarily a benefit for outdoor plants since slugs and snails aren’t common indoor pests. So it’s helpful if you live in a climate warm enough to grow peace lilies outdoors year-round or if you take your plants outdoors for the summer months.
Slightly Lowering Soil pH
Like many plants, peace lilies prefer to grow in soil that’s just on the acid side of the pH scale. Coffee grounds can help you get there, although maybe not as fast as you might think.
It was a surprise to me that this wasn’t a bigger benefit. But coffee grounds lose much of their acidity in the brewing process, so they’re closer to a neutral pH. The University of Arizona found that the pH of used coffee grounds varied from 4.6 all the way up to 8.4, so on average, that puts coffee grounds slightly on the acid side at about 6.6 or so.
How to Use Coffee Grounds in Peace Lily Plants: 3 Ways
Now for the practical stuff: How do you actually use the coffee grounds?
Some people will tell you to use coffee grounds as mulch- dumping them right from the coffee maker onto your plant’s soil.
Do not do this! You must use the grounds properly. If you don’t, you could harm your plant and create new issues for yourself (which we’ll get to in more detail a little later on).
Another caution is to use the right kind of coffee. Flavored and instant coffees have added substances that can harm your plant, so stick with grounds from regular coffee. And no surprise here- organic coffee is always preferable.
There are three safe ways to take advantage of coffee grounds for peace lilies:
- Using spent grounds to make a weak-coffee watering solution
- As a soil amendment mixed into potting soil
- As a compost ingredient
I’ll show you how to use each method properly:
1. Weak Coffee
This is my preferred method of using coffee grounds- in my opinion, it’s the easiest and most fool-proof one.
Here’s my peace lily pre-treatment, looking a bit blah- kind of like me before my coffee.
I’ll admit I’ve somewhat neglected this plant, and it’s got the yellowing and brown leaves to prove it. Go ahead and cut these sickly leaves off- they’re done for.
When using weak coffee for your fertilizer, run a normal coffee brewing cycle, then run plain water through the same grounds. After it cools, use it to water the plant.
Here’s the weak coffee I brewed after making my regular morning pot. See how the coffee is a translucent brown instead of opaque black:
Once the coffee is cool, put in a watering can and use it to water your plant, giving enough so the excess runs through the pot’s drainage holes:
That’s all there is to it.
Here’s my same plant about 2 weeks later. It’s looking much more healthy and energetic, and there’s a new blossom forming:
I think this plant has responded very well, and I will continue to give a coffee boost. But not too often- you only need to give the weak-coffee fertilizer every 2 months. In between treatments, water with plain water every week or as needed.
2. Soil Amendment
Mixing used coffee grounds into the soil can be a great way to help peace lilies thrive.
Lindsey Hyland, expert gardener and founder of Urban Organic Yield, says she likes to mix coffee grounds into potting soil for her peace lily. Here’s how she does it:
“First, using gloves, gently mix 1/2 cup of used coffee grounds into a gallon of potting soil. Ensure the grounds are completely blended in with the potting soil before adding them to the plant’s container. Then carefully scoop the mixture around the base of your peace lily and lightly pat it down so it’s firmly rooted. Finally, give your peace lily some extra water if needed, as this will help everything settle nicely into place.”
This is most effective when you’re repotting your peace lily. For most plants, that’s every 1-2 years.
You could also take some of this soil mixture and apply it to the top of the existing soil as it naturally compacts over time.
3. Compost Ingredient
If you use homemade compost as part of your peace lily soil blend, coffee grounds are a good addition to your compost recipe.
But here again, you need to use care. The University of California Agriculture and Natural Resources recommends that grounds should only make up 15-20% of your compost pile. If there are too many, you could throw off the pH of the compost batch or potentially kill off helpful decomposers, like worms.
I’ve been adding coffee grounds to my compost for years. Since I buy unbleached coffee filters, I throw those in too:
The good news is you can use this compost not just for a peace lily, but any plants at all in your garden. I use a tumbling compost bin, but a regular compost pile or vermicomposting system work wonderfully too.
Potential Problems with Coffee Grounds in Peace Lilies
Using coffee grounds is a great way to give your peace lily a boost, but there are some dangers to be aware of. Most of these problems come from using coffee grounds in the wrong way (like using them as mulch) or applying too much of them.
Mo Bhula, RHS Chelsea Medalist from The Botanical Archive, agrees. “The issues with using coffee grounds in your peace lilies come from applying the grounds directly to the soil; this often encourages root rot by over-saturating your lily with moisture.”
And when you see good results from coffee grounds, don’t get over-eager. Mo adds, “When it comes to fertilizing peace lilies less is more. These plants have adapted to thrive in the rainforest where nutrients on the forest floor are sparse. As a result don’t overdo it with the coffee ground fertilizer (as tempting as it might be).”
Here’s what to watch out for:
Throwing off Soil pH
Coffee grounds are slightly on the acidic side of the pH scale, which is one of the reasons we use them in our acid-loving peace lilies. But if you add coffee grounds too often or in too high a quantity, you could make your soil too acidic for your plant’s liking.
To avoid this problem: Use coffee fertilizer sparingly. You can give a weak-coffee watering every 2 months during the growing season, or mix in coffee grounds whenever you need to repot your plant.
Coffee grounds can help repel annoying slugs and snails, but they may attract other pests, including ants, flies and roaches. And no one wants that!
To avoid this problem: Do not apply used coffee grounds straight onto the soil surface- pests like the moist, decaying environment they create. Instead, use coffee grounds as liquid fertilizer or mix it thoroughly with potting soil to avoid attracting unwanted visitors.
Excessive Moisture Retention
Coffee grounds are great for helping the soil retain moisture, and peace lilies need consistent soil moisture to thrive. But too many coffee grounds can lead to an overwatering problem, resulting in root rot and potential fungal growth.
To avoid this problem: Don’t apply straight grounds to the soil surface. Use the dilute coffee watering method, or mix in just about 1/2 cup of grounds into about 16 cups of potting soil.
More Ideas for Homemade Fertilizer for Peace Lily Plants
There are many ways to make a homemade fertilizer for peace lily plants. Here are a few ideas that you can try:
- Eggshells are rich in calcium and have the potential to stimulate growth if they are ground into a powder and then mixed into the soil. See how we use eggshells in our plants here!
- Save the water when you make hard-boiled eggs. Allow to cool, then use it to water your peace lily.
- Banana peels are an outstanding source of potassium. Cut up banana peels into about 1-inch pieces, put them in a glass jar and add water to cover. Put on a tight-fitting lid, and soak the peels for 1-2 days. Strain the peels out and water your plants with the liquid. You can also throw those peel chunks into the compost after soaking.
Frequently Asked Questions about Coffee Grounds for Peace Lilies
So, do peace lilies like coffee grounds? My final answer is yes, as long as they’re used properly and in moderation. Based on my experience, coffee grounds can really perk a peace lily up- kind of like how coffee perks me up!
I hope you’ve found this post helpful. If you still have any other questions or tips for using coffee for peace lilies, I’d love to hear them. We learn best from one another’s thoughts and experiences, so please feel free to share in the comments!