Quick Search

Save The Grounds! How to Use Coffee Grounds in the Garden

Read time: 3 mins
Save The Grounds! How to Use Coffee Grounds in the Garden
John H. Jun 14, 2024

From Cup to Crop: Turn Coffee Waste into Garden Gold

We all know that a cup of coffee can give you a morning boost, but did you know coffee grounds can also perk up your plants? While used coffee grounds can be tossed into compost with great results, putting them directly on the soil might not be the best idea. So let’s dig into the burning question - are coffee grounds really good for your garden?

Coffee is the world's second most traded commodity after crude oil. So, it's natural to ask if all those spent coffee grounds can be reused in some way. Coffee grounds contain nitrogen, which is a vital nutrient for plants. Nitrogen helps them grow, photosynthesize and bear fruit. Despite the nitrogen content, coffee grounds are generally too acidic to be added directly to the soil. In fact, researchers found that when spent coffee grounds are directly applied to city vegetable gardens, they can even reduce or inhibit plant growth.

There is a safe way to get nitrogen from your coffee grounds to your plants, however. Let's delve into how you can make the most of your coffee grounds in the garden.

The Coffee Ground Breakdown

If you're keen to use coffee grounds in your garden, composting is a great way to go. Many gardeners make their own compost in compost heaps or bins in their backyard. Composting coffee grounds is easy and nutrients like nitrogen, potassium and phosphorous make it very beneficial for your soil. Too much of a good thing can have unwanted effects though, so no more than 20-35 percent of the compost pile material should be made up of coffee grounds. Too much can prevent the whole pile from decomposing. Composting your grounds is as easy as throwing them into your compost pile. Don’t’ forget to toss those used coffee filters in with them. They’ll break down too!

The Ground Rules for Coffee Based Fertilizer

Just piling spent grounds under your plants isn't a great idea. Coffee grounds, whether fresh or used, can stop moisture and air from getting into the soil because of their fine texture. They can also compact readily, making it hard for plants to grow. However, when smaller amounts are blended thinly into the soil, they can improve its texture. Experts suggest adding a nitrogen fertilizer as you do this. Microbes in the soil will help break down the coffee grounds, making nitrogen more readily available to the plants. Another easy way to use your grounds safely, is to make a tea by soaking spent coffee grounds with water overnight and using it as a liquid fertilizer. This is a plant tea though; we don’t recommend drinking it.

Don’t Get Fresh: What About Unused Coffee Grounds?

While not always recommended, using fresh coffee grounds on plants can work in some situations. You can sprinkle them around acid-loving plants, such as blueberries, ferns, or hydrangeas. They can also be mixed into the soil for root crops, such as potatoes, carrots, or parsnips, which all thrive on slightly acidic conditions. Fresh coffee grounds may also be used as an effective weed barrier as they suppress both unwanted plants and certain fungal pathogens. 

Coffee Grounds Unfiltered: More FAQ

Should I use coffee grounds as mulch?

● Spent coffee grounds aren't ideal for mulch as they can create a barrier, preventing water from penetrating the soil. If you want to amend the soil, apply a thin layer to an empty plot and cover it with a layer of wood chips.

How else can I use coffee grounds in the garden?

● Coffee grounds can also deter pests like slugs and snails. Some claim they repel cats from using your flower and veggie beds as a litter box. Additionally, coffee grounds can be used as worm food in vermicomposting with a worm bin.

Spent coffee grounds are so much more than just remnants of your morning brew. To safely unlock their benefits in your garden, just remember to follow these simple rules: use in moderation, compost when possible, and know your plants’ pH preferences. Coffee grounds are a versatile and sustainable resource for enhancing your garden’s health and productivity. So the next time you brew your morning coffee, don’t toss the grounds! Instead, take a minute to raise your mug and toast a greener gardening journey fueled by coffee waste!

Leave a comment