Are Used Coffee Grounds Good for Tulips?
You've repurposed ladders into trellises and broken concrete into walls, so the next step in creating a sustainable household ecosystem is using old coffee grounds for plants. Coffee grounds add important nutrients to the soil for tulips (Tulipa spp.), but you need to exercise some caution in using them. Tulips of all 120 wild species and 2,300 varieties thrive in full sun in U.S. Department of Agricultural plant hardiness zones 4 through 10.
Like all plants, tulips need the essential elements of nitrogen, phosphorus and potassium as well as secondary nutrients, such as calcium and magnesium. Fertilizing tulips with some nitrogen before they bloom will encourage blooming, but using too much nitrogen promotes leaf growth at the expense of blooms. Tulips also prefer soil that has a soil pH level close to neutral. Test your soil with a soil test kit to determine its pH.
Components of Coffee Gounds
Coffee grounds meet the test for an all-purpose, slow-release fertilizer, as they contain both essential and secondary nutrients. Phosphorus, potassium, magnesium and copper all appear in good amounts, while the amount of nitrogen is less than what many plants need. The low amount of nitrogen and its slow release into the ground, make it a good choice for tulips. Although coffee grounds are slightly acidic, they fall into an acceptable range on the pH scale.
In the Soil
When adding coffee grounds to your soil, err on the side of using too little rather than too much, so as not to make the soil overly acidic. Before planting tulips, dig the grounds into the planting soil about 6 to 8 inches, using a volume of about 25 percent grounds to 75 percent soil. Do this in the summer before planting so the grounds have a chance to slightly decompose.
In Compost and as Mulch
Adding coffee grounds to your compost pile gives them time to release their nitrogen and dilutes their acidity. You'll also increase the heat in your compost pile, effectively killing weed seeds and speeding up the breakdown of organic materials. When sprinkling coffee grounds directly of the tulip's soil, work them in a few inches or cover them with leaves or other mulch to reduce the chance of their acidity burning the tulip leaves.
- Floridata: Tulipa Spp.
- The New Sunset Western Garden Book; Kathleen Norris Brenzel, Editor
- Sunset: The Starbucks Coffee Compost Test
- Oregon State University: Coffee Grounds Perk up Compost Pile With Nitrogen
Susan Lundman began writing about her passions of cooking, gardening, entertaining and recreation after working for a nonprofit agency, writing grants and researching child development issues. She has written professionally for six years since then. Lundman received her M.A. from Stanford University.