Using Coffee Grounds in the Garden

Do you throw coffee grounds away? Not anymore! Coffee grounds have many uses that can boost your garden and flower beds, just like it gives you a boost when you drink the coffee itself!

Composting coffee grounds not only reduces what goes to the landfill, it also benefits your plants. After reading this, will you still throw your coffee grinds away?

Used Coffee Grounds in the garden

Used coffee grounds can have many purposes in your garden. On top of recycling your coffee grounds in the garden, you will actually make plants thrive!

Coffee grounds for fertilizer

Not many of us have a compost pile or find the time to do proper composting. So practice simply putting coffee grounds directly into the soil!

It will not add nitrogen to the soil immediately. In the first phase, coffee grounds add organic material to the soil. This enhances drainage, aeration, and water retention.

Moreover, coffee grounds increase growth of microorganisms and earthworms.

  • If you are into vermicomposting, coffee grounds can be used as worm food.

In a second phase, nutrients contained in the coffee grounds are released by microorganisms as they break it down.

Coffee grounds for mulch

Spreading layers of coffee grounds as mulch is beneficial when in lower quantity. Coffee grounds shouldn’t exceed more than 25% (one-fourth) of the mulch mix.

Otherwise, traces of caffeine from the ground coffee might have detrimental effects on some plants. If there are too much coffee grounds in the soil, plants will grow slower or stunted until such a time that soil organisms are able to break the coffee down.

  • Coffee grounds will not kill plants. It just takes time for them to recover in case of excess amounts.

Coffee grounds for soil mix

As long as you keep the portion of coffee grounds below one-fourth (25%), you can mix coffee grounds with potting soil mix.

You can use this coffee-enriched soil mix to:

Garden pests – coffee grounds keep ants, rabbits, slugs and snails away

Since caffeine has a negative effects on pests,  it’s possible to use coffee grounds to protect your favorite plants from being eaten.

  • Note: as with most repellants, it helps to provide “decoy plants” that will attract the pests, too. A good example of this is planting nasturtium to lure aphids away from your roses and other favored plants.
  • Nasturtium vs Aphids

Coffee grounds as a cat repellent

It seems cats do not like coffee grounds. If cats come in your garden to poo, you might want to try spreading some around!

  • The strong scent makes cats feel their favorite spots for “number 2” are already contaminated.

Used coffee grounds to topdress a lawn

Coffee grounds naturally have high nitrogen content. This is particularly well-suited for grass.

  • Used coffee makes for a great lawn topdress.
  • Apply directly, no need to mix it with other materials.

Fresh ground coffee

Coffee grinder, the old wooden manual type, and a few grains of coffee for preparing coffee grinds for the garden.Fresh coffee grounds can also be used in your garden. This is ground coffee that hasn’t been used to make a drink. Sometimes older coffee loses its savor and must be thrown away. Use it in the garden!

  • Just remember that fresh coffee grounds are acidic whereas used coffee grounds are neutral.
  • Indeed, making coffee transfers the acid to the drink, so used coffee grinds aren’t acidic anymore.

Although it isn’t a recommended practice for most plants, it is, however, favorable in some respects:

Fresh ground coffee is good for acid-loving plants

You can add fresh coffee grounds around plants like:

There are also many vegetables which like slightly acidic soil including root crops like radish and carrot. All you need to do is mix a bit of fresh ground coffee in the soil during planting time.

  • Tomato, on the other hand, doesn’t grow well when coffee grounds are added in the soil.

Fresh ground coffee to suppress weeds

Weeds that grow around plants – especially those with allelopathic properties – can be minimized by using fresh coffee grounds. However, this should be used with a lot of care. As you suppress weeds, you might be also suppressing some beneficial fungal microorganisms.

Deter pests and other animals with fresh coffee grounds

Like used coffee grounds, fresh coffee grounds discourage pests and animals from coming to your plants and in your garden in general.

What do coffee grounds bring to the garden?

Why are coffee grounds good for soil?

Coffee grounds, both used and fresh, have about 2% nitrogen. This is beneficial when added to your compost.

The C/N (carbon-nitrogen ratio) for roasted coffee grounds is 20, or about 20 parts carbon to one part nitrogen. For used coffee grounds, any water you put in the filter while making coffee also removes acidity. This ensures that used coffee grounds have a neutral pH level of 6.5 to 6.8.

Can I put coffee filters in the soil or compost pile?

Whereas the coffee grounds themselves are considered green compost material, coffee filters are also interesting and are considered brown compost material. Simply throw them in your compost.

You can also use coffee contained in special aluminum capsules and the like. Simply open them up with a knife on a cutting board and collect the grounds in a bowl or pail.

Coffee grounds are risk-free

Coffee grounds, since they go through the process of roasting, are always considered “healthy material” for composting and growing beds.

Unlike some store-bought fruits and vegetables, coffee is rarely treated with pesticides and chemicals. It can thus be used without fear of contaminating your garden soil with chemical products.

Where to find coffee grounds for a garden

A handful of roasted coffee beans ready to be ground up and used in the garden.Even small gardens can absorb large amounts of coffee grounds.

  • Check with coffee shops in your area. Some franchises already prepare packs of used coffee grounds for customers to take away.
  • Restaurants often have coffee machines that produce quite a lot of coffee grounds.

You’ll notice that when asked politely (and not during rush hour!), many eatery managers will be happy to set some coffee grounds aside for you.

  • Make it even easier for them: bring a container that closes with a lid, such as a large plasticware or a bucket with a lid.
  • Agree on a schedule, and stick to it. Coffee grounds should be disposed of quickly, or they’ll start molding within three to four days.
  • Having two containers makes it easy to swap an empty one for the full one.

Many families brew coffee every day. Even small capsules add up! An average coffee-drinking family will produce over a gallon of coffee grounds a month.

  • Get together with neighbors. If they don’t want to use the grounds themselves, they’ll certainly be happy to keep them for you!
  • Why not set up a community compost? Coffee grounds are perfect “compost material” that there can never be too much of.

Smart Tip for Used Coffee Grounds

Some people mix used coffee grounds in their mushroom soil substrate.

Read also


Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Coffee grounds for the garden by Rosalyn & Gaspard Lorthiois, own work
Coffee mill by Rosalyn & Gaspard Lorthiois, own work
Coffee grains, roasted by Rosalyn & Gaspard Lorthiois, own work (home-roasted, too!)