We love coffee grounds. Coffee grounds have a long list of uses in the garden. It’s amazing how this thing we so often throw away can be so useful. Form composting to soil amendments coffee grounds in the garden are good for a long list of things. Since we’ve learned about so many ways we could use it, we never sent them off to the landfill again. In this article, we are going to dive into how to use coffee grounds in the garden.
Table of Contents
Why put coffee grounds in the garden?
Coffee grounds can be used in the soil to deter pests and as part of your composting systems. The uses for coffee grounds include:
- As an ingredient in composting
- As a deterrent for insects and slugs
- As a soil amendment and source of Nitrogen for plants
Are coffee grounds good for plants?
Yes. The coffee grounds that are left after you’ve made your morning coffee are high in Nitrogen. Nitrogen is the macronutrient plants need the most. Nitrogen is a major component of chlorophyll, the thing that makes a plant’s leaves green. It also makes up an important part of plants’ amino acids.
Coffee grounds also contain other nutrients such as Phosphorus, potassium and trace elements. But overall Nitrogen is the most significant nutrient your plants will get from coffee grounds.
Coffee Grounds in Compost
There are many ways to speed up the composting process and boost the quality of your compost. One of the ways of doing that is with coffee grounds. If you’re familiar with aerobic composting it’s the nitrogen-rich material like manure, food waste or in this case coffee grounds that’s responsible for the increase in temperature of your compost pile.
Coffee grounds increase the temperature in your pile very quickly. The great thing about using coffee grounds over food waste is that you can add nitrogen, without adding moisture. Coffee grounds have a 1:20 carbon to nitrogen ratio. This makes coffee grounds the perfect choice if you’re compost is ever too wet and not heating up properly due to not enough nitrogen.
Coffee grounds in the worm bin
Our worms love coffee grounds. If you can’t get your hands on animal manure to feed to your worms coffee grounds is a very good option. Coffee grounds don’t attract pests the way animal manure or decomposing food can. If you are composting with worms indoors adding coffee grounds would be a good option.
Coffee grounds for garden pests
When used correctly coffee grounds can deter pests like mosquitoes, wasps, snails and slugs. Most insects hate the smell of coffee grounds.
Coffee grounds for slugs
Used coffee grounds don’t kill slugs but they are a good way to deter slugs and keep them away from your plants. If you’re using coffee grounds to deter slugs apply coffee grounds to the soil surface and create a barrier around your plant.
What will kill slugs is caffeine. If your slug problem persists making a caffeine spray or using damp fresh grounds may work better to get rid of slugs in the garden.
Coffee grounds for cats
Got a cat problem? Coffee grounds just may be the answer. Coffee grounds can be used in the garden to keep cats out. Cats hate the smell of coffee. If you are looking for a humane way to keep cats out of the garden sprinkle the coffee grounds in and around your garden bed. The cats will find somewhere else to go and you will be adding nitrogen to your soil as well.
Where to use coffee grounds in the garden
When using coffee grounds in the garden it can be mixed into the soil or added to the soil’s surface. If you’re mixing it into the soil water the arear daily after adding it to the soil. You should wait at least 2 weeks before planting in the area. Before planting poke your finger down a couple of inches into the soil just to make sure it isn’t heating up.
Coffee grounds are very acidic and are particularly useful for plants that prefer slightly acidic soil. Additionally, coffee grounds are very good at retaining water. Too much coffee grounds can cause the soil to retain too much moisture and lead to problems such as fungal growth and root rot. When using coffee grounds directly I would advise against them making up more than 10% of your soil mix.
Coffee grounds for potted plants
Used coffee grounds are good for potted plants in moderate quantities. If using coffee grounds on potted plants you want to use it more like a thin mulch layering it on top of the soil and not mixing it into the soil. The goal in this situation would b to feed the plant a small quantity of nitrogen overtime when watering. Also, by leaving it on the surface of the soil any heat generated as the coffee grounds break down can easily escape and not burn your plants.
Coffee grounds for seedlings
Caffeine is known to inhibit germination and plant growth. Therefore, it isn’t recommended to use coffee grounds when germinating seeds or transplanting seedlings. Ensure your coffee grounds are composted before applying them around young plants.
Are coffee grounds and eggshells good for plants?
I already explained that coffee grounds are an excellent source of nitrogen but eggshells are good for plants as well. Eggshells provide an excellent source of calcium to the soil. When using eggshells you should apply it as a fine powder. I go through all the steps to make eggshell powder in this article.
Calcium is an essential micronutrient in all plants. If you need more details on the role calcium plays in plants and how it can be added to the soil I have all the details in this article.
Final Thoughts
Coffee grounds are very useful in the garden. I love adding them to my various compost bins and, when appropriate, directly to my soil. Another great thing about coffee grounds is they are usually free. If you have a large garden you can ask your local coffee shop to save the grounds for you. They are usually more than happy to do so. If you’re going this route bringing a resalable container for them to store the grounds is a great way to help them help you.
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