Home Gardening Center Tip Sheet: Coffee Grounds In the Garden and In Compost

By Sonia Uyterhoeven

·· Soil & Compost ··


Using Coffee Grounds In the Garden and In Compost


We recycle our paper and plastics, so why not add one of our morning staples--coffee--to the list? Composting is a natural way of recycling, breaking down organic waste, and turning it into nutrient-rich matter. Coffee grounds can be used in the composting process in a variety of ways.

1. Coffee grounds can be applied directly to your garden; they can be applied as a top dressing to nitrogen-loving plants such as azaleas, roses, lettuces, and most perennials. Although the grounds are highly acidic, most of the acidity is removed during the brewing process.

2. Add coffee grounds and filters to your compost pile. Coffee grounds act as a green material that is high in nitrogen. Combined with brown material, coffee helps to create a rich environment for your compost micro- and macro-organisms to do their job of breaking down the waste.

3. Coffee grounds can be used in worm bins along with other household waste to create vermicompost (indoor compost made by red worms).

4. Coffee grounds can be used out in the garden to create slug barriers around your hostas, ligularias and other plants that are susceptible to slug attacks. Make sure that you use caffeinated coffee as it is the caffeine that will deter and even kill the slugs. Simply create a small 1/2 to 1 inch wall of coffee grounds around the susceptible plant. Replenish the barrier as necessary.

Ways to Use Compost:


Compost can be mixed directly into your soil, applied as a thick layer of mulch, used in a thin layer on your lawn, or soaked in a bucket to make "compost tea" for watering your indoor or outdoor plants. Compost cannot replace soil, but should be used to amend it.

1. The amount of compost that you need to amend soil will depend on the nutrients present in the soil and the condition of the soil. Compost helps break up heavy clay soil, improves water retention in sandy soils, and nourishes soil that has been depleted of important nutrients. Have your soil tested to find out what it needs.

2. Do not get intimidated by numbers. Sometimes people recommend adding as much as 4 inches of compost to newly established beds. This is to create optimal conditions. If this feels like too much, add anywhere from to 1/4 to 1 inch of compost to the bed once or perhaps even twice a season (spring and fall). Getting into a yearly routine will cut down the quantities that you will need to create fertile soil. Also remember that less is better than none. Nature replenishes the soil every year by having deciduous trees drop their leaves to create a rich leaf litter. Gardeners should get into the same good habit.

3. You can either incorporate the compost into the soil as you plant or add an inch on top of established planting (this is called top-dressing). It will seep into the ground through the season. If you are using fine or coarse bark mulch around your woody plants, add compost into the bark mulch mixture.

4. In the vegetable garden combine compost with aged cow manure to create an environment that is rich in organic matter and ideal for most vegetables. You can either amend the soil in the fall or the spring, depending on when you have time. Heavy feeders such as tomatoes, corn, and squash benefit from a mulch of 1/2 inch of compost.

5. In your window boxes and potted plants, add 1/4 of compost once or twice a year to revitalize your container plants. Work it into the top layer of the soil, discarding old soil if necessary.

6. The advice varies slightly for planting trees. The soil you plant a tree in should be similar to the soil in the surrounding area. If the new soil is too rich, the roots of the tree will not grow past the nutrient-rich material used to fill the hole. Add compost if you are planting in heavy clay or sandy soil that has difficulty holding nutrients. If you are amending the planting hole, try and amend as much of the area as possible. Add compost into the mulch as part of the top-dressing.

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·· Soil & Compost ··



Generous support for the Home Gardening Center has been provided by Kenneth and Ellen Roman.