Tomatoes need a steady diet of nitrogen, phosphorus and potassium to grow the juiciest and more flavourful fruit.
According to experts, there is a kitchen scrap item that contains these nutrients – coffee grounds.
Jim and Mary Competti of I Grow Tomatoes blog explained that most fertilisers are made up of what’s often referred to as the “big three” of nutrients – nitrogen, phosphorus and potassium. All of these nutrients work together to help create “strong and healthy tomato plants”.
Nitrogen is essential for helping to grow and fill out the foliage of tomato plants so the foliage can convert sunlight into nutrients.
Phosphorus helps tomato plants produce buds and flowers. Without it, tomato plants would struggle to set flowers, therefore “greatly reducing yields”.
Tomato plants need potassium to “help improve the quality of the fruit produced” as well as “reduce the chance of tomato plants succumbing to disease”.
What’s more, potassium is critical at the time of flowering to help plants produce and ripen fruit.
Thankfully, spent coffee grounds “contain all of the ‘big three’ vital nutrients, but they also contain trace elements of calcium, magnesium, zinc, and iron – all nutrients that tomato plants also use to “grow and produce the best fruit that’s full of flavour”.
But the power of coffee grounds goes beyond just being used as a fertiliser.
They can actually be used to help improve the soil as well, allowing tomato plants to “grow stronger and push out a more extensive root system” – a root system that can “improve harvest totals dramatically”.
For the benefits of added nutrients, it’s best to add used coffee grounds at the time of planting.
This initial boost of nutrients and the additional moisture can be vital to help transplants quickly establish and produce strong early root growth.
To do so, mix two to three tablespoons of coffee grounds into the planting hole before adding the tomato plant. Be sure to plant your tomatoes deep to give them the best chance at soaking in nutrients.
When mixing in grounds, only use spent coffee grounds as fresh grounds contain acids that can change the soil’s pH and be “harmful to tomato plants”.
Using spent coffee grounds doesn’t just stop at planting time though. You can use them to top-dress tomato plants all throughout the growing season.
Jim and Mary said: “Every three to four weeks, sprinkle on a few tablespoons around the base of each tomato plant. This helps to provide plants with a low and steady stream of nutrients every time it rains or you water.
“The grounds on top will also help to loosen the soil and add structure as they break down. So not only are the coffee grounds adding nutrient value to your plants, they are improving the soil at the same time.”
