How often can you fertilize tomatoes with coffee grounds? You should pay attention to this!

Coffee grounds are recommended by amateur gardeners around the world for a number of gardening problems. From fertilizing to mulching to pest control – there doesn’t seem to be anything a spoonful of used coffee grounds can’t do. But can you also fertilize tomatoes with coffee grounds? We will explain how you can use the home remedy so that it does not harm your tomato plants.

How does coffee grounds help the tomato plants?

can I fertilize tomatoes with coffee grounds?

Coffee grounds provide good amounts of essential nutrients all of which are needed for healthy growth and should still benefit tomatoes by:

  • increases the nutrient content
  • balances the pH
  • the soil temperature stabilizes
  • the water storage increases
  • reduces harmful bacteria and fungi
  • germination improves
  • the growth rate increases
  • promotes earthworm activity
  • serves as a natural and organic insecticide
  • Weeds reduced

Fertilize tomatoes to avoid nutritional deficiencies

The most important nutrients that coffee grounds add to the soil are:

  • nitrogen
  • phosphorus
  • magnesium
  • copper

Since nitrogen and phosphorus are two of the three main nutrients for plants (the other is potassium), coffee grounds are a great way to fertilize your tomato plants. While nitrogen levels can vary, it’s often the most valuable nutrient in coffee grounds.

There is also evidence that coffee grounds are good for earthworms and compost worms, which in turn helps improve soil.

In addition, research suggests that the natural bacteria and fungi that are on the decomposing coffee grounds reduce harmful fungi and even prevent them from settling in the soil of tomato plants.

Coffee grounds are supposed to drive snails away from the vegetable patch

Finally, coffee grounds can also be used as a natural insecticide. The reason for this is the caffeine it contains. Typically, insecticides have deleterious effects as they also kill beneficial worms and pollinating insects, but coffee grounds are a much safe and natural alternative. For example, there is some evidence that coffee grounds drive away insects such as ants, snails, and nudibranchs.

However, there is still debate over the science on the subject, as some believe the caffeine is gone after the coffee is made and others say there is still a lot left in the coffee grounds.

Coffee grounds make the ground sour?

Coffee grounds can make the soil acidic

Tomatoes are an acidic food, so it’s no surprise they like a slightly acidic base. Tomato plants prefer a soil pH between 6.0 and 6.8, while a neutral pH is measured at 7.0.

Science disagrees on whether coffee grounds make the soil acidic. In short, unused coffee grounds are acidic, but most of the acid is lost in the brewing process. This means that the used coffee grounds only have a slightly acidic pH value of 6.5-6.8. However, since this pH is exactly in the range of what tomato plants prefer, coffee grounds are a great addition to the soil.

The pH of soils that are treated with coffee grounds increases in the first three weeks and then slowly decreases. For this reason, it is a good idea to check the pH of the soil every few months.

How to use coffee grounds as tomato fertilizer

Only fertilize tomatoes with coffee grounds

There are basically three ways to use used coffee grounds as fertilizer or soil conditioner for your tomato plants:

  • You can spread it directly on the floor
  • mix with mulch
  • compost it first

Basically you can put the coffee grounds directly on the soil of your tomato plant. But coffee powder can easily clump together if used in large quantities, preventing air and moisture from reaching the bottom. So it’s best to mix the coffee grounds with mulch or compost it first. Leaves, bark and pine needles can be used as mulch for tomato plants.

Spread a 1.5-inch layer of used coffee grounds around the base of your tomato plants and cover them with 5 to 8 centimeters of organic mulch.

Another way to fertilize tomatoes with coffee grounds is to sprinkle 1 cup of used coffee grounds around the base of your tomato plant and work it into the top 5 to 8 cm of the soil using a trowel or small cultivator. This stimulates the decomposition of the coffee grounds and prevents problems with soil compaction.

Coffee grounds on the composter

If you compost the coffee grounds first, you can put them on the compost heap in the fall so they will be ready to use in the spring. You should pay attention to three things:

  • The coffee grounds should not make up more than 20% of the total compost.
  • Wait 2-3 months for it to decompose before placing it in your yard.
  • Apply the already finished compost to the bottom of your tomato plants in a 2 to 5 cm layer.

Whichever method you choose, the important thing is: Don’t let the coffee grounds (or compost) come into direct contact with the tomato plant. The same goes for mulch. You should leave a space of at least 2 centimeters between the coffee grounds and the lower leaves. This is because coffee grounds and compost can cause mold, and their high nutrient content can chemically burn the plant.

How much coffee grounds should you use on your tomatoes??

Tomatoes with coffee grounds fertilize how much

While coffee grounds are great for the soil and compost, they can also be too much of a good thing. You should use coffee grounds in moderation. The high levels of nitrogen and potential caffeine can unbalance the soil or compost if used in excess.

Limit the amount of coffee grounds on your compost to a maximum of 20 percent. Coffee grounds are considered green material, like fresh grass clippings and kitchen trash, and must be mixed with brown material like dried leaves. You can read here how to properly compost.

For a standard compost heap with dimensions of 90 x 90 x 90 cm, this means no more than 570 cups of used coffee grounds. As you can see, it would be pretty hard to go over this limit.

90 x 90 x 90 cm = 0.72 cubic meters

20% of this is 0.144 cubic meters

Since 1 cubic meter = 4000 cups, that makes about 570 cups of coffee grounds

When and how often should you fertilize your tomatoes with coffee grounds?

Put tomato seedlings in the open ground

You can use the coffee grounds when you plant the young plants outdoors and then 1-2 times a month. Typically, most plants prefer fertilizer in their growing season, just before fruiting, but any other time is fine.

Be careful not to use too much coffee grounds as this will affect the frequency of use. Check the pH of your soil regularly.

How to fertilize tomatoes with coffee grounds:

  • Put the composted coffee grounds in the planting hole to improve the soil composition. It will act as a slow release fertilizer and provide the soil with nitrogen for several weeks.
  • Mulch the tomatoes with composted coffee grounds (or coffee grounds + mulch) throughout the summer to help retain moisture in the soil, prevent weeds, and add nutrients to the soil.
  • Work the coffee grounds into the soil in autumn and let them decompose directly in the soil. Experts recommend enriching the soil with organic material such as compost, manure or coffee grounds twice a year.
  • For tomatoes in a pot: Mix the coffee grounds and soil in a ratio of 1: 1 and pour the mixture into the pot so that the bottom is completely covered. Always allow the coffee powder to dry out well before use to avoid mold formation.

Fertilize tomatoes in a pot with coffee grounds