- Fertilizers & Compost
Coffee grinds for plants in your garden
Grounds For Your Garden
Coffee grounds make great compost additives, soil enhancers and pest deterrents. It's an inexpensive way to fertilize your garden, build a richer compost yield and promote worm activity.
As Compost and Worm Promoter
Spent coffee grinds make a great additive to a compost pile as they have a very high carbon to nitrogen level. Initially, the coffee will provide a good level of acidity and add a great texture to your compost, though over time it will not make the compost generally more acidic, as microbes in the composting process will turn the grinds from acidic to neutral pH levels. A common complement to coffee grinds in a compost pile is egg shells. Worms love coffee grounds too; adding coffee grounds to compost piles (or worm bins) will promote their activity as they feed on them. Because worms love to feed on coffee grounds, you can also toss the grounds in your garden soil to promote their activity in general areas.
Garden Soil Additive
As you would expect, coffee grinds are acidic with a pH level of about 4.0. So for plants that prefer more acidic soil content, like azaleas and tomatoes, coffee grounds make a great additive to the soil. Obviously, be careful to not add large concentrations of coffee grounds to plants that are highly sensitive to acidic levels. In general, mixing coffee grounds with garden soil for a topping layer in gardens is an excellent way to add organic matter to your fertilizer mix. Mixing the coffee grounds with soil allows for a diffused, even concentration as well as prevents mold which may occur if coffee grounds are spread as clumps. Other plants that like the acidic taste of coffee grinds include: hydrangeas, blueberries and rhododendrons. Homemade organic fertilizers are rewarding and satisfying - adding coffee grinds to the mix helps you to control the pH levels.
Your average household spent-coffee grounds contains roughly .05% concentration of caffeine. Though this is not enough to kill slugs (i have read that you need about a 2-3% caffeine concentration to achieve this effect), it is a great slug and snail deterrent. Sprinkle the grounds around the tender plants and veggies that you want to discourage slugs from addressing.
Managing and Collecting
Keeping wet, spent coffee grounds in a can or a bag can turn into a moldy smelly mess, so it is good practice to deploy your grinds on a frequent (a few times a week, if not daily) basis.
If you do not have a lot of coffee grounds at home, the office is a great place to collect them; place an empty coffee can with a sign on it next to the coffee maker at work and soon you will have your fill of this lovely garden additive. Local cafes usually have a spent coffee grounds program; Starbucks' Grounds For Your Garden program is a good example. So if you want bulk, go ask your local coffee shop! (you'd be surprised at how many folks have Starbucks coffee grinds in their flower beds!)
Here are some other suggestions for managing your coffee grounds project:
- Go ahead and toss your coffee filters into the mix along with the spent grinds. All the filters that I have ever come across are biodegradable and are fine to add to a compost pile (and makes it easier and more convenient to recycle your grinds).
- Mix your grinds with equal amount of organic potting soil and add water to create a fast acting liquid fertilizer (in a big five-gallon bucket mix 1 lbs coffee grounds with 1lbs soil and the balance with water).
- Ring your plants with coffee grounds just before watering them or before it starts to rain; this will provide a great slow-release source of nitrogen. As mentioned above, this also serves as a great slug and pest deterrent.