A couple of posts ago, I wrote about how peace lilies grow really well when you add the right amount of coffee grounds. It might seem like an odd marriage, coffee grounds & your plant, but you tried it for your peace lilies and lo and behold, they thrived. That probably has you wondering, do any other houseplants of mine like coffee grounds too? If so, which houseplants?
Do indoor plants like coffee grounds? Yes! Coffee grounds can be especially beneficial to houseplants when used as a mulch, pesticide, compost, or fertilizer. You can even water your plants using coffee. Just make sure to limit your coffee quantities, as too much caffeine can stunt plant growth and increase the risk of fungal diseases.
In this article, I’ll walk you through everything you need to know about feeding your houseplants coffee grounds and/or liquid coffee. From which plants like to be fed coffee to adding coffee as a natural fertilizer, and the one caveat to using coffee on your plants that all gardeners need to know!
Which Houseplants Like Coffee?
The first mistake you can make is assuming that every houseplant in your indoor garden will appreciate a good splash of coffee or some grounds spread amongst their soil. Coffee is high acidity, so only certain houseplants have a taste for it.
In that regard, your plants are kind of like us people. Remember, there are some people who need a coffee (or two) to get up and going every day and there are other people who are negatively affected by a single cup of coffee!
I’ve compiled the following list of houseplants that do well with coffee grounds & being watered with coffee.
I had to start by talking about peace lilies or Spathiphyllum. I have a whole blog post dedicated to the peace lilies love of coffee grounds that I’ll be publishing very soon. Peace lilies are grateful for the acidity of coffee for one, as well as the organic matter and nutrients found within coffee grounds.
The cyclamen in the Primulaceae family includes 23 perennial flowering plant species. This houseplant hails from eastern Iran, parts of the Mediterranean Basin, Europe, and Somalia (only one species though).
Cyclamen flowers are beautiful in hues like red, white, and shades of pink, sometimes all in one gorgeous bud. Your cyclamen will welcome being fed coffee grounds from time to time.
Another plant that likes coffee is the jade, which goes by names like the money plant or lucky plant. It’s technically called the Crassula ovata. The jade plant comes from Mozambique and KwaZulu-Natal in South Africa.
As a succulent, a happy jade plant might sprout white or pink flowers, and you can keep yours happy by occasionally mixing coffee grounds in with freshly added potting soil or potting mix every 6 to 12 months.
Are you surprised the Schlumbergera or Christmas cactus is a coffee lover? It is indeed! These cacti, of which there are upwards of nine species in all, come from southeastern Brazil’s most coastal mountains.
The Christmas cactus certainly doesn’t receive any coffee there, but it can in your indoor garden. Otherwise, give this houseplant plenty of humidity and shade.
Gardeners and non-gardeners alike swoon over the beauty of the philodendron. It’s hard not to, as this plant with its large, bright green leaves gives a tropical air to any home, apartment, or office space.
The philodendron doesn’t like being fed coffee often, so keep it to a rare treat for best results.
That’s the rule of thumb for the golden pothos as well. If you need a refresher, the golden pothos or devil’s ivy is called the Epipremnum aureum.
The golden pothos comes from the Araceae family as well, which explains its coffee preferences. This beautiful Polynesian plant grows well in a planter or a hanging basket and can thrive in almost every room in your home as long as the room has at least one window to allow at least a little natural light into the room.
I’ve had at least one type of pothos growing in my bedroom for the last 8 years. There’s just something so nice about having a pothos in your bedroom.
As a true rose, miniature roses never get overly large. They’re the perfect addition to any indoor garden then because not only are they lovely and elegant, but they won’t hog up too much precious space, either.
You can get mini roses in all the colors of their fuller-sized counterparts, and these smaller flowers are tougher to kill (not like you’d want to).
Miniature roses are big fans of nitrogen and acid, so coffee grounds at the plant base or liquid coffee used instead of your usual morning or afternoon watering now and again can make this plant perk up.
The last houseplant that you should feed coffee to is the African violet or Saintpaulia. These Gesneriaceae family members include 10 species of herbaceous perennials.
The flowers of an African violet are an alluring purple, hence the name (also yes, this plant does come from Africa).
Like miniature roses, African violets can’t get enough of nitrogen or acid, so you can feed them coffee a little more regularly than you might some of the other houseplants on this list.
How to Fertilize Houseplants with Coffee
Now that you know a few of the more common houseplants that like coffee, you’d like to feed them some.
Before we get into a few of the best methods for feeding and fertilizing your houseplants with coffee, I’d like to point out the one caveat I mentioned at the beginning of this article.
Never feed or fertilize any plants with coffee that has milk or any other additive in it. Only ever use black coffee when applying coffee to your plants.
Using coffee with milk or sweeteners like sugar, cream or syrups to feed or fertilize your plants can cause mold, fungus gnats, fungal disease and other undesirable results along with possibly killing your plant.
That being said,
Here are some of the best methods you can use.
Mulching might seem like something you do for outdoor plants only, but your houseplants don’t mind it either. Depending on what you add to the mulch, you can maintain the health and hydration of your indoor plants through mulching.
Good houseplant mulch should include organic matter such as straw or compost. You can add some coffee grounds to your homemade mulch mix as well, but be careful not to use too much.
This is one application in which a heaping helping of coffee is not the answer. Piling the coffee grounds around seeds or the plants themselves can worsen the health of your plants over time.
Also, your plants might not grow to their full potential because of the caffeine in the coffee grounds. Further, the coffee that smothers your plants leaves little room for nutrients to get in.
If you’re growing seedlings that have yet to germinate especially, then you want to avoid mulching with coffee grounds until the plants are more well developed. Even when your plant matures, keep an eye out.
Oh, and don’t be fooled into thinking used coffee grounds have less caffeine than unused grounds.
According to Caffeine Informer, when the University of Navarra’s Department of Nutrition, Food Science and Physiology, School of Pharmacy compared the caffeine in used versus unused coffee grounds, the used ones still had caffeine, between 3.59 to 8.09 milligrams.
Some indoor (and outdoor) gardeners prefer to use coffee grounds only as a pesticide. For slugs especially, this is effective. All you have to do is scatter the coffee grounds on your houseplant’s soil and the slugs will stay away.
At the very least, the texture of the coffee grounds will keep slugs away. This is similar to using broken eggshells scattered around the soil to prevent slugs.
By far, the most popular usage of coffee grounds for an indoor garden is fertilizer. Besides their nitrogen content, coffee grounds also have phosphorus, potassium, and further micronutrients. That makes them a great choice for a slow-release fertilizer on some species of houseplants.
You want to use a light hand as you apply the coffee grounds to your houseplant’s soil for fertilizing purposes. Think of it like, “less is more“.
For more information on other homemade fertilizers, I’ve also written an entire article dedicated to fertilizing indoor plants naturally with homemade fertilizers, which also includes used coffee grounds.
If you want to err on the side of caution and avoid the direct application of coffee grounds on your houseplants, try adding the grounds to your compost pile instead.
The nitrogen and carbon in coffee grounds in compost will attract earthworms and microorganisms, helping your compost break down faster and keeping it rich in nutrients.
Don’t just dump in nothing but coffee grounds though. You want to keep them as roughly 20 percent of the ingredients comprising your compost.
Didn’t finish your second coffee for the morning? That’s no problem. When you’re done with that cup ‘o joe, and it’s had time to cool off, you can use it as a water alternative for your plant by pouring liquid coffee right in.
Tip the coffee mug or pot so the liquid hits the soil and not the plant leaves or flowers. If your houseplant’s leaves become brown at the edges after the coffee application, then either refrain from using as much coffee next time or maybe skip it altogether.
Dos and Don’ts for Using Coffee on Your Houseplants
Coffee can sort of be a double-edged sword for your houseplants. The benefits have become quite apparent after reading to this point, but you have also discovered that the caffeine in coffee can hurt some acidic plants.
That’s not even getting started on what would happen if you fed coffee to a more alkaline plant. It’d probably be dead pretty quickly.
To keep all the rules about coffee ground usage straight, I assembled this handy list of dos and don’ts. Call it to mind every time you feed your houseplants coffee to ensure you do so safely!
DO Use Coffee Grounds Seldomly
You can’t get through a single day without coffee, but your houseplants? They’re not nearly as dependent on the stuff as you are. When you want to give them coffee, it’s by no means a daily thing. Instead, leave it as an occasional treat.
If you’re using coffee as fertilizer, then follow the normal fertilization schedule for your houseplant. That might mean fertilizing every six weeks depending on the plant and the time of year.
For compost, you can add a touch of coffee grounds into the mix whenever you start a new compost pile. As a pest control measure, sprinkle coffee grounds when the bugs start showing up, but avoid it otherwise.
When watering your houseplant with liquid coffee, only do this once every two to three weeks.
DON’T Let Your Pets Around an Indoor Garden with Coffee Grounds
Slugs aren’t the only creatures that don’t like coffee grounds. If you have a dog or cat who gets curious (and hungry) around your houseplants and they happen to take a big ol’ bite, you could accidentally make your pet very sick.
The caffeine in coffee is toxic to our pets. It’s possible that coffee ingestion can lead to death, and that goes for coffee grounds as well. Please keep your pets safe!
DO Know the Acidity of Your Plants Before Feeding Them Coffee
If you need a refresher on what makes something more acidic or alkaline, don’t worry. If your plants are acidic, then their pH is 1 to about 6.
Anything from 8 to 14 is considered basic or alkaline, which is less acidic.
To make it more clear, gastric acid in your body has a pH of 1, lemon juice a pH of 2, and tomato juice a pH of 4. Milk, which is more neutral but still somewhat acidic, has a pH of 6. On the alkaline side, hand soap has a pH of 10 and bleach a pH of 12.
Black coffee is a 5 on the pH scale, so it’s not the most acidic substance, but it does contain much more acid than water. H2O is neutral.
DON’T Pour the Liquid Coffee in Hot
I know I mentioned this earlier but you can burn your plants if you leave them on a sunny windowsill all afternoon on a hot summer day, but that’s not the only way you can scorch your houseplants.
Pouring hot coffee can also damage your plants severely.
Always let the coffee cool down to at least room temperature before pouring it into your houseplant’s pot. If you want to wait even longer until the coffee is cold, that’s more than fine too.
DO Try Making Your Own Compost
Even if you have no intention of adding coffee grounds to your compost pile, you should have a compost pile nonetheless. Making your own compost is maybe not the cleanest or nicest task indoor gardeners can do, but it’s super satisfying.
You get to choose exactly what you’re feeding your houseplants, giving you more control over their care.
You want your compost to be a combination of green matter and brown matter.
Both are named by the color of the ingredients:
Green matter includes items such as tea bags, grass clippings, and veggie scraps.
Brown matter includes coffee grounds, shredded newspaper, and dried leaves.
Oh, and if you see earthworms in your compost pile, that’s a good thing. As I mentioned, they eat the organic materials to speed up their decomposition so you can use your compost sooner.
DON’T Ignore the Problems Coffee Can Cause in Your Indoor Garden
Caffeine stunting your plant growth and the coffee grounds posing a serious risk to your pets aren’t the only issues you have to worry about when using coffee grounds for your houseplants.
The ingredients in the coffee can lure in insects and critters. This maybe isn’t as much of a problem since your garden is indoors and not outside, but if you leave your window open on a nice day, you could have some uninvited guests hanging out in your houseplant’s pot.
Also, it is recommended that you put your houseplants outside from time to time and it’s not at all uncommon to pick up a few hitchhiking insects on your houseplants that end up making it inside.
Further, it’s possible that your plant’s moisture retention could change. The particles and organic materials within the coffee grounds grab and hold onto the soil’s moisture, drying it out.
You then feel inclined to water, even overwater your plant, possibly causing root rot.
None of this is to say you shouldn’t use coffee grounds on your houseplants. You should just be aware of the risks associated with doing so and try your best to avoid these.
DO Monitor Your Plant for Changes
On that note, watch out for changes in your plant once you start feeding them coffee. If their leaves become brown, curled, or wilted, cut back or stop using coffee altogether.
I hope you found this article helpful. I spent a lot of time putting it together, if you think it might help someone else, please share it on social media. It would mean a lot to me. Thanks!