In the past we’ve talked about what effect coffee grounds can have on plants, but we haven’t discussed whether coffee grounds can make good fertilizer for vegetable plants, especially tomato plants.
There is a lot of information out there about how to properly fertilize your tomato plants and what products to use for the best results, but will coffee grounds will improve the success of your tomato plants?
The honest answer is, maybe.
I know that’s not what a lot of people like to hear, but it’s the truth. While there hasn’t been any scientific proof that coffee grounds will improve the rate of growth or number of tomatoes your plants produce, there is some scientific data that backs up the reasoning for why people believe that coffee ground are good for tomato plants.
Tomato Plants Like Slightly Acid Soil
The main reason that this idea that coffee grounds can help to fertilize your tomato plants is that tomato plants thrive in slightly acidic soil. Used coffee grounds can help soil become slightly more acidic when they are used as fertilizer.
Now, when we say slightly more acidic, we do mean slightly.
In some cases, coffee grounds could actually be alkaline or neutral meaning they are not acidic and therefore not helping the plants, but in most cases the grounds are just acidic enough to help the soil, but not by much.
Coffee grounds contain around 2% nitrogen as well as varying amounts of phosphorus and potassium which are all very important for the growth of tomato plants. By mixing some coffee grounds into the soil below your tomato plants you’re introducing these nutrients that the plants need to thrive.
However, coffee grounds do not act like traditional fertilizer and will take some time to affect the soil enough to help the plants. In fact, it may have the opposite effect on the soil for a couple weeks before releasing enough of the nutrients in the soil to help.
This is why people claim that coffee grounds help out with tomato plants over the long run, but not necessarily during the up front growing. So, keep that in mind if you’re looking for something to help get your plants growing quickly.
Should You Use Coffee Grounds to Fertilize Tomato Plants?
Knowing the information above, there’s nothing wrong with using some of your used coffee grounds to help fertilize your tomato plants, but don’t expect some miracle growth hack to come from it. You also need to make sure that you’re not overdoing it by using too much on your plants.
Take about 1 cup of used coffee grounds spread around the base of your tomato plant and work it into the top 2-3 inches of the soil. This will help the coffee grounds break down and start to release the nutrients into the soil.
You can also use coffee grounds in a compost bin and then use that compost as fertilizer to help the plants grow. Just make sure that you keep the coffee grounds to less than 20% of the compost material as you don’t want to make the compost too acidic. This can be more harmful than good for the tomato plants.
Traditional Fertilizer vs. Coffee Grounds
If you’re looking for a fertilizer to help improve your tomato plants in the best way possible, and you’re open to using store bought fertilizer, there are options out there that are specifically designed for these types of plants and will most likely offer greater benefits than coffee grounds would.
If you would rather not use those types of fertilizers though, used coffee grounds are a great, natural, way to help create a more suitable soil for the tomato plants to thrive in.
Coffee grounds can be very useful when it comes to gardening, but it’s important to understand why plants may benefit and how to properly use them to achieve the best results possible.
FAQs
Coffee grounds contain around 2% nitrogen as well as varying amounts of phosphorus and potassium which are all very important for the growth of tomato plants. By mixing some coffee grounds into the soil below your tomato plants you're introducing these nutrients that the plants need to thrive.
How much coffee grounds should I put in my tomato plants? ›
Avoid Excessive Application: Remember to use coffee grounds in moderation. While they can be beneficial for tomato plants, applying too much at once can lead to issues with soil pH and nutrient imbalances. A thin layer of coffee grounds spread around the base of the plant is typically sufficient.
Which vegetables do not like coffee grounds? ›
Coffee grounds inhibit the growth of some plants, including geranium, asparagus fern, Chinese mustard and Italian ryegrass. Conversely, grounds (used as mulch and compost) improve yields of soybeans and cabbage.
How often should you put coffee grounds on plants? ›
You shouldn't sprinkle more than a thin layer around your plants, or else the coffee grounds can become impenetrable, preventing water from getting into the soil. If you evenly sprinkle coffee grounds around the plants once a week or so, the amount will likely be okay.
What is the best fertilizer for tomatoes? ›
Look for a fertilizer that has a high middle number, which represents phosphorus, in the N-P-K analysis. Commonly available fertilizer analysis that are great for tomato seedlings include 8-32-16 and 12-24-12. Mix the fertilizer with water according to package directions.
Can I just sprinkle coffee grounds on plants? ›
Coffee grounds are an excellent compost ingredient and are fine to apply directly onto the soil around most garden plants if used with care and moderation. Coffee grounds contain nutrients that plants use for growth.
Can too much coffee grounds hurt plants? ›
Depending on what was in your compost mix, be cautious of how much compost you use. Excessive amounts of compost or coffee grounds can lead to foliage burn and nutrient toxicity. Just like with store-bought fertilizer, a little goes a long way.
Which vegetable plant likes coffee grounds? ›
Acidic-loving plants such as azaleas, blueberries, hydrangeas, rhododendrons, and roses will benefit from a sprinkling of coffee grounds around the base of plants. Vegetable crops that may benefit from coffee grounds include carrots, cucumbers, peppers, potatoes, and radishes.
Can I use leftover coffee to water plants? ›
It's okay to water plants with leftover coffee or to add coffee grounds to the compost pile but learning when and why to use coffee in the garden will protect your plants. Only use black, unflavored coffee with this method to offer plants a source of nitrogen which can fertilize certain indoor and outdoor plants.
Why do tomatoes not like coffee grounds? ›
The grounds do not contain the nutrient balance that tomatoes need to thrive, and adding too many grounds will affect the soil's pH. Tomato plants can tolerate slightly acid soils, as low as pH 5.5.
'Coffee grounds are an effective houseplant fertilizer owing to their high nitrogen content,' says Rachel Bull, Head of Gardens at H&G, and a fellow houseplant aficionado. 'Coffee grounds contain potassium, magnesium, calcium, and other trace minerals too, which are all vital nutrients that plants need to grow.
Do peppers like coffee grounds? ›
Coffee grounds can contribute to a healthier soil environment for your pepper plants. Here's how: Enhanced Drainage: Coffee grounds have a slightly coarse texture, which can help improve soil drainage. This is particularly beneficial for pepper plants, which prefer well-draining soil to prevent root rot.
Why put eggshells in your garden? ›
The shell of a chicken egg is comprised of about 96% calcium carbonate (CaCO3). Calcium is an essential plant nutrient and moderates soil acidity. Fast-growing plants deplete the soil of calcium very quickly so egg shells are an ideal supplement and feed for outdoor flowers, vegetables and fruit trees in your garden.
What fertilizer is put in a hole when planting tomatoes? ›
Throwing some compost in the planting hole isn't enough for tomatoes. They should be fertilized from the get-go. To get tomato plants off on the right foot, feed them with a fertilizer that has a balanced formulation. That would be something like a 4-4-4 or 5-5-5.
Is Miracle-Gro good for tomato plants? ›
Tomato plants have big appetites and need a steady supply of plant food to grow their best. Miracle-Gro® Performance Organic® Edibles Plant Nutrition Granules feeds both your plants and the beneficial microbes in the soil (which help plants take up all the nutrition they need) for up to 6 weeks.
What fertilizer increases tomato size? ›
Damu works by helping plants move photosynthates from the leaves where they are made to the fruit. This helps improve size of tomatoes ahead of picking.
Are eggshells and coffee grounds good for tomatoes? ›
The idea here is that blossom end rot is caused by a calcium deficiency, so adding calcium-rich eggshells to the soil could provide calcium to your tomatoes (or other plants that suffer from blossom end rot).
Should coffee grounds be wet or dry for plants? ›
Though gardeners most often use grounds that have been brewed, fresh coffee grounds can also be used. Only composted coffee grounds should be mixed into the soil, as fresh grounds will have a higher acid and caffeine content which may burn plant roots. Make sure that grounds aren't too wet to discourage possible mold.
Are banana peels good for tomato plants? ›
Banana peels are also brimming with potassium, which is excellent for plants like tomatoes, peppers or flowers. “Banana peels also contain calcium, which prevents blossom end rot in tomatoes,” the Cape Gazette adds.
