Do Coffee Grounds Make Good Potting Soil?

Acidity and Alkalinity

• Alkaline soil is soil with a pH level higher than 7.0. Alkaline soil will not hold moisture or nutrients as well as acidic soil, so in general, very alkaline soil is not good for most plants. Coffee grounds are useful for lowering the pH levels in soil, reducing the alkalinity. Coffee is also used to improve soil conditions for acid-loving plants like rhododendrons, blueberries, azaleas, avocados and hydrangeas.

Composting

• Composting is an inexpensive and resourceful way of creating nutrient-rich soil for your garden. In composting language, compost piles are created by layering equal parts "green materials" and "brown materials." Coffee is used as a green material, meaning it is a material high in nitrogen. Materials high in nitrogen feed the microbes that cause decomposition, speeding the composting process.

Mulch

• Coffee can be mixed with potting soil when planting, or it can be used as a mulch when spread over the top of the soil. Crumble the grounds and spread them thinly -- do not allow them to "cake" together, as this can create pockets so high in nitrogen as to be toxic. Dried coffee grounds work better than wet coffee grounds, especially when using a lot at once because wet coffee grounds are susceptible to mold.

Liquid Form

• Your plants can also benefit from "drinking" coffee, just like you do. Steep half a pound of coffee grounds in 5 gallons of water for 24 hours. Use this mixture as a liquid fertilizer and use it to water your plants. Some gardeners even pour leftover cold coffee straight into the soil.