There are a variety of fertilizers you can use in your houseplants' soil. Because you are using it in your home, the best and safest kinds are natural fertilizers. Coffee is a natural fertilizer and can add nutrients, particularly nitrogen, to your soil.
There can be some danger when adding coffee or any fertilizer to your soil. You have to consider the soil's pH and the effect the fertilizer will have on it.
Is coffee good for houseplants?
Coffee can be good for many houseplants. The question, though, is coffee good for a particular plant. The questions is, “What is the pH of your soil?” The pH of your soil will determine if your houseplant will benefit from coffee grounds.
Coffee grounds have a unique feature. They can be new or used. If coffee grounds are new, then they are acidic. If coffee grounds are used, then they are neutral. Knowing the different pH levels of the coffee you are adding will help to determine which kind to add to which plants.
Benefits of coffee grounds for houseplants
The main ingredient of coffee that is beneficial to houseplants is nitrogen. Your houseplants need nitrogen for growth and processing food. They also use it in the process of creating chlorophyll.
List of plants that like coffee grounds
Before and after adding coffee grounds to your houseplants soil, check the pH of the soil. If your plant likes acidic soil and your soil is neutral or alkaline, then you should add new coffee grounds to make the soil more acidic. If your plant likes neutral soil and the soil is alkaline, then you can add used coffee grounds to make the soil neutral. You may be able a little bit of new coffee to your soil if it is really alkaline, but be careful you don't make it too acidic.
Below is a list of common houseplants and their preferred pH levels. Use a soil pH test kit to see what your soils pH level is before adding coffee. Then use one of the methods listed below in “How to add coffee” section below.
Pothos - 6.1 - 6.5
Aglaonema - 5.6 - 6.5
Jade Plant - 6.1 - 6.5
Asparagus Fern - 6.5 - 6.8
Chinese Money Plant -Pilea Peperomioides 6.0 - 7.0
Yucca - 5.5 - 7.5
Air Plant - 5.5 - 6.0
Spider Plant 6.0 - 7.5
Peace Lily 5.8 - 6.5
Aloe 7.0 - 8.5
English Ivy 6.0 - 7.8
Dragon Tree 6.0 - 6.5
Calathea (Prayer Plant) - 5.5 - 7
Rubber Plant 5.5 - 7.5
Bromeliad 5.0 - 6.0
Kalanchoe 6.0 - 6.5
Ponytail Palm 6.5 - 7.5
Phalaenopsis Orchid 5.5 - 6.5
Philodendron 5.5 - 6.0
Crown of Thorns 6.0 - 6.8
Christmas Cactus 5.5 - 6.0
ZZ Plant 6.0 - 7.0
Snake Plant 5.5 - 7.5
Schefflera 6.0 -6.5
Dieffenbachia 6.1 - 6.5
Lipstick Plant 6.0 - 8.0
Hoya Rubra Krimson Princess
Aralia Fabian 6.1 - 6.5
Variegated Arrowhead Vine 5.5 - 6.5
Ficus Alli 6.0 -6.5
Hoya Carnosa Variegata 6.0 - 6.5
Monstera Deliciosa 5.5 - 7.0
Haworthia - Zebra plant 6.6 - 7.5
Bird’s Nest Fern 5.0 - 5.5
Happy Bean Plant 5.0 - 7.0
Ficus Bonsai Tree 6.0 - 6.5
Cast-Iron Plant 5.5 - 6.5
Fiddle-Leaf Fig 6.0 - 7.0
Cactus 5.5 - 7.0
Weeping Fig 6.0 - 6.5
Paddle Plant 6.1 - 7.3
Lavender 6.5 - 7.5
African Violets - 5.8 - 6.2
Miniature Roses - 6.5 - 7.5
Cyclamen 5.5 - 6.5
Which houseplants do not like coffee grounds?
There are no plants that we know of that would not like coffee grounds. When you understand that new coffee grounds will make your soil acidic and used ones will bring it closer to neutral, you understand coffee grounds can be used on all houseplants. The real issue is what is the soil's condition when adding the coffee grounds. This determines which kind and how much coffee to add.
Where to get coffee grounds for houseplants
Of course you can always save your own coffee grounds after you use them. You can also buy new coffee grounds if you need to use new ones in your houseplants soil. If you are going to buy new coffee grounds and you don't want to spend too much money, you should go to a local discount store and see what they have in stock. A lot of times you can find coffee at half the price you would find it in a regular store.
Another great way to get used coffee is from a local coffee shop or restaurant. They have no use for them after they have been brewed. They toss them out when they are done with them. Call a local coffee shop and ask the manager if you can have some of their spent coffee grounds. Most of the time they will put some aside for you. Just be courteous and pick them up when they say it will be ready. You don't want to leave a bunch of used coffee grounds sitting in their store.
How to store coffee grounds
Used coffee grounds are moist because water has been passed through them. To store them properly, you need to dry them out. Spread the coffee grounds out on some newspaper or was paper. Make as very thin layer. The thinner the layer, the fast they will dry.
If you want to dry them out fast, place the used coffee grounds on a baking sheet. Turn your over on to 250 degrees Fahrenheit. Then put them in the oven for about 5 minutes.
Once they are completely dry, put them in a container with a top or a plastic zip bag. Store them in a cool, dry place. You don't have to store them in your refrigerator, but putting them in the refrigerator may help to keep them longer.
Best way to use - liquid, new, used, composted
You can use coffee in your houseplants pots in any form. This includes liquid, fresh coffee grounds, used coffee grounds, and composted coffee grounds.
Using coffee in liquid form is the hardest to control. When you pour liquid coffee into your soil, the houseplants will drink up it up. This will not give you an opportunity to test the soil after you add the liquid coffee and before the plant absorbs it. Also, the pH of liquid coffee is 4.85 to 5.10. It is very acidic.
New coffee grounds can be used right out of the bag. Just remember that they are acidic.
Used coffee grounds can be placed in the soil right after they are brewed or can be stored and used later. Let hot coffee grounds cool before adding them to your houseplant's pot.
You can also compost your coffee grounds for use with your houseplants. Composting your coffee grounds will render them neutral. Fresh coffee grounds will raise the pH of your compost pile. You can also pour liquid coffee into your compost pile.
How to add - new potting soil, existing potting soil
If you are just putting your house plant in a pot or you are repotting it, then you can add coffee directly to the soil. This will give you an opportunity to test the pH levels before placing your houseplant in the soil.
If your houseplant is already in the pot and you want to add coffee to the soil, test the pH of the soil and determine whether you should add new or used coffee. Then add a little around the plant, but not directly on the plant. This is especially important when adding fresh coffee grounds. Any coffee grounds making direct contact with your houseplant could damage it. Test the soil again and repeat if you need to add more.
Moisture drainage
Clumps of coffee can make it more difficult for your soil to drain water properly which can harm your houseplant. If you are adding a little, then make sure it is spread out and mixed in well. If you adding enough that it appears clumping may occur, then mix the coffee grounds with some straw or other organic material before placing it in your pot.
Will it attract bugs or rodents
Coffee grounds do not attract bugs or rodents. There is some science that suggest it repels them.
You don't have to worry about coffee grounds bring unwanted pest to your houseplants.
Conclusion
Coffee grounds can be beneficial to your houseplants if your apply them correctly to your soil. Measure the soil pH before and after adding grounds to ensure your plants aren't harmed.