Tomato plants need a steady supply of nutrients to produce the juiciest, most flavorful fruit, and there are some common kitchen leftovers that contain all three key nutrients.
Tomatoes need a steady supply of nitrogen, phosphorus and potassium to produce the juiciest, most flavorful fruit.
Experts say that coffee grounds, a common kitchen waste, are rich in these nutrients. Jim and Mary Competi of the blog I Grow Tomatoes explain that fertilizer is mostly made up of what are commonly referred to as the “big three” nutrients: nitrogen, phosphorus, and potassium. These nutrients work in harmony to help grow “strong, healthy tomato plants.”
Nitrogen plays a key role in promoting the growth and development of tomato leaves, allowing the leaves to convert sunlight into nutrients. Phosphorus is essential for tomato plants to sprout and flower. Without phosphorus, tomatoes will have a hard time flowering and “yields will be significantly reduced,” reports the Express.
Potassium is necessary for tomato plants to “improve the quality of the fruit that grows” and “reduce the chances of your tomato plants becoming susceptible to disease.” Additionally, potassium is crucial during the flowering stage to help your plants set and mature fruit.
Thankfully, used coffee grounds contain “all three major nutrients,” as well as trace elements like calcium, magnesium, zinc, and iron — all nutrients that tomato plants use to “grow and produce the best, most flavorful fruit.” But the power of coffee grounds doesn't just end when used as a fertilizer.
Coffee grounds also improve the soil, allowing tomato seedlings to “grow stronger and develop more widespread roots,” which can “dramatically increase yields.” For additional nutrients, it's best to add used coffee grounds at planting time.
This initial supply of nutrients and extra moisture is essential for transplants to establish quickly and for early root growth to be strong. To do this, mix 2-3 tablespoons of coffee grounds into the planting hole before planting your tomato seedlings. Make sure to plant your tomatoes deep so they can absorb the nutrients.
If you do mix in coffee grounds, only use used coffee grounds. Fresh coffee grounds contain acids that can change the soil pH and be “toxic to tomato plants.” Used coffee grounds can be used as a top dressing for tomato plants throughout the growing season, not just at planting time.
Jim and Mary say: “We sprinkle a few tablespoons around the base of each tomato seedling every three to four weeks. This provides a steady supply of nutrients to the plants with every rain or watering. Plus, the coffee grounds sprinkled on top help loosen the soil and give it structure as they decompose. So not only do the coffee grounds provide nutrition to the plants, they improve the soil at the same time.”
