Potting a coffee ground garden

Essential Guide to Crafting a Coffee Ground Garden

Steve Russell - February 15, 2023

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Like many people, you probably can’t start your day without a steaming cup of coffee. But what do you do with that heap of leftover grounds and filters? For many, the final destination for coffee grounds is the trash, but a coffee ground garden promises better nourishment for plants and another opportunity to reduce waste. 

With the right techniques, your plants can enjoy better nourishment all while you gulp down another mug of your favorite brew. 

Grounds as Composting Materials

Composting is a great way to reengage with what we perceive to be waste. Consumerist culture demands that we mindlessly take and discard, but shifting our mindset allows us to see fruit peels, overripe vegetables or other scraps as useful and valuable. We begin to look for ways to use materials in multiple ways or for new purposes, cutting back on waste by a large margin.

If you’re already enjoying the fruits of a compost garden, consider adding coffee grounds to your array of materials. Ideally, there should be a 4-to-1 ratio of brown and green compost materials. Brown materials are carbon-rich dry scraps, like these:

  • Branches and dry sticks
  • Newspapers
  • Dry leaves
  • Dead plants
  • Straw
  • Pine needles

Coffee grounds are part of the complimentary green materials, all rich in nitrogen. Other materials include food peels, scraps, eggshells and other debris. 

If you’re new to composting, dedicate a space for this endeavor. Starting on bare earth allows natural soil nutrients and worms to work their way through. Cover with your materials and keep this plot moist and covered. 

Beginners and experienced composters should consider adding coffee grounds to their gardens as a powerful green, nutrient-rich material. 

Nutrient-Rich Fertilizers

If composting isn’t in the cards for you, whether due to space or time, coffee ground gardening techniques work in regular plots and pots, too. Again, coffee is naturally rich in nitrogen, magnesium, calcium and potassium, so your grounds have much to offer. 

To fertilize, dump a handful of grounds on top. Then, take a rake and scratch up the surface of the soil so that both materials are mixed thoroughly. You can also sprinkle small amounts onto container gardens. Be sure to keep coffee grounds displaced, as large clumps act as a water-resistant barrier. 

For an alternative method, steep two cups of grounds in a large bucket of water. This liquid-based fertilizer takes a large amount out of the acidity of brewed coffee so that it doesn’t harm the plants. 

Dinner for Worms

Worms are coffee lovers just like us. Adding coffee grounds to your garden attracts worms who add to the natural diversity of the garden. However, overflowing on the grounds may be harmful to worms as they are still acidic. 

Vermicompost is a type of composting where worms produce diverse and nutrient-rich soil by digesting food scraps and other materials. Indoors or out, these worms live in a moisturized bin with ventilation holes. Though this technique takes some more know-how, it is another great usage for coffee grounds. 

Mitigating Pest Interference 

While many plants and worms love coffee grounds, there are creatures that wish to avoid them at all costs. As smooth and slimy animals, slugs and snails avoid abrasive materials like coffee grounds. 

In a controlled research experiment, coffee grounds also suppressed fungus rots and wilts on plants like spinach and cucumber. While there is no guarantee that coffee will eliminate weeds and diseases, its antimicrobial properties are helpful in this endeavor. 

Additionally, cats and rabbits loathe the smell of coffee and caffeine flavors. If these animals are nibbling on greens or leaving their mark on your plots, a sprinkling of coffee may help. 

Tools and Materials For Your Garden 

Coffee grounds are an immeasurably vital addition to any garden to enhance nutrients and mitigate pests. What tools might you need to get started with your own composting or fertilizing journey? Use these helpful lists.

For container gardens indoors or on windowsills, you may need: 

  • Containers with proper drainage so that the grounds do not soak up all the water
  • Gloves to sprinkle the grounds
  • Bucket to steep the grounds if making liquid fertilizer
  • Two watering cans for water and coffee mixture

Composting plot materials: 

  • Brown materials like newspapers and dry leaves to make the 4-to-1 ratio
  • Composting plot or container
  • Worm bin if a vermicomposter
  • Ripped-up paper coffee filters as a carbon source

Larger garden materials: 

  • Rake to mix grounds and soil
  • Bucket and watering cans if using liquid fertilizer method

Larger gardens might need more grounds than the typical morning pot of coffee, too. If you need additional supplies, consider stopping by the local cafe as they may have a grab-and-go system for grounds. These stores throw away thousands of pounds of grounds each day, but your usage stops plastic-wrapped bags from landing in dumps or landfills. 

Best Plants for a Coffee Grounds Garden

While many plants could benefit from enhanced nitrogen and protection from pests, some varieties would particularly flourish from the acidity of a coffee ground garden. 

The great vivid bursts of flowers in a hydrangea or rhododendron are nourished by acidity, as well as these other plant varieties:

  • Blueberry bushes
  • Carrots
  • Radishes
  • Lily of the valley
  • Azaleas

On the other hand, some greens are harmed by the natural acidity found in coffee. Tomatoes are a popular plant for many gardeners, but they should be kept away from coffee ground gardens. Caffeine is also known to stunt growth, so younger plants and seedlings are not the best beneficiaries for grounds, either. 

Dig into a Better Garden

With a little digging, you can stop tossing away valuable nutrients each morning with your cup of joe. Coffee ground gardens can be enjoyed in indoor containers or plots of land in the backyard or homestead. With their high levels of nitrogen and ability to ward off pests, grounds are ideal for many flowering and vegetative plants in your garden. 

So take one last swig and nourish your energy, your array of plants and the planet with this ideal waste-reducing technique. 

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About the author

Steve Russell

Steve is the Managing Editor of Environment.co and regularly contributes articles related to wildlife, biodiversity, and recycling. His passions include wildlife photography and bird watching.