Grow A Thriving Green Lawn With A Natural Fertilizer From Your Kitchen

You'll find numerous websites that tell you to sprinkle coffee grounds directly onto your lawn. They claim that coffee grounds can improve your soil, add vital nutrients, deter pests, and kill weeds, among other benefits. You might also find coffee shops giving their coffee grounds away for free, which should make you wonder: If it's such an excellent fertilizer, why aren't they selling it? Well, the scientific evidence isn't that simple. Yes, spent coffee grounds can have its benefits, but not when applied directly onto your lawn, and – like other do's and don'ts of lawn care – used only in moderation.

The best way to add coffee grounds to your lawn is to add them to a compost pile. Composted coffee grounds can add minor amounts of iron, nitrogen, potassium, phosphorus, and other plant nutrients to your soil. The structure of the spent grounds can also aerate your soil and improve your soil's ability to retain water. Applying spent coffee grounds directly, however, has all the wrong effects on your lawn.  A coffee plant adds a toxin – caffeine – to its seeds to prevent competitor plants from growing. Applied directly to your lawn, the leftover caffeine in spent coffee grounds can inhibit seed germination and early plant growth, kill beneficial microbes in the soil, and deter earthworms from breaking down the nutrients in coffee grounds.

If you want to use coffee grounds to improve your lawn, learn how to compost. Professor Linda Chalker-Scott of Washington State University recommends that coffee grounds should make up no more than 20% of your compost. Over time, composting leaches the toxins out of coffee grounds while releasing its nutrients. Those nutrients attract soil fungi and microorganisms that can benefit the growth of your lawn. Once it's properly composted, you can mix it into your soil when you are starting a new lawn, or spread it over your existing lawn during the winter and let it work its way into the soil.

Beyond adding nutrients to your soil, composted coffee grounds can help you maintain the appropriate amount of soil moisture for growing a healthy lawn. Frequent watering is key to new lawns, but over-watering can drown your grass seed and rot its roots. Composted coffee grounds can improve your soil structure by adding pockets of air to allow for better drainage of clay soil and better water retention of sandy soil.

What composted coffee grounds probably won't do, however, is make your soil more acidic, contrary to some advice you can read online. The bitter-tasting acid in coffee ends up in your cup after brewing, not in the grounds. The pH of spent grounds is relatively neutral.