6 easy (and free!) types of homemade plant food for tomatoes

heirloom tomato growing on a vine

Like you, tomato plants need lots of nutrients to grow big and strong. But after the cost of seeds, soil, grow lights, heat mats, planter bags, and more, you may be looking for an affordable homemade fertilizer option rather than more products that you can buy.

These are 6 of our favorite ways to make homemade plant food for tomatoes to combat the most common nutrient deficiencies. 

What nutrients do tomatoes need?

Tomatoes need all of the common plant nutrients, but take care to pay special attention to the levels of nitrogen, phosphorus, potassium, calcium, and magnesium that you are providing to your tomato plants.

Deficiencies in any of the major nutrients can result in problems like stunted growth, deformation of the plant, blossom end rot, discoloration, cracking of the fruit, and many more issues.

Epsom salt fertilizer

Epsom salt is often used as a fertilizer for tomato plants. It provides much-needed magnesium to your plant. 

The most common sign of magnesium deficiencies in tomatoes is chlorosis in the older leaves. You will notice that the leaves will develop light brown dots. Magnesium deficiencies are more common if your tomatoes are planted in sandy or acidic soil, or if they have lived through cold and wet periods.

To make homemade epsom salt fertilizer to help your plants gain much-needed magnesium, dissolve 1-2 tablespoons of epsom salt (common bath salts) into a gallon of warm water. Deeply water your tomato plant with the epsom solution, and repeat occasionally throughout the season as needed.


Compost made from veggie scraps in your kitchen is another amazing tomato fertilizer. It contains three important nutrients: nitrogen, phosphorous, and potassium.

Make sure to save your food waste including vegetable trimmings, fruit peels, and even egg shells and coffee grounds. 

It is easy to make compost at home to later use as plant food for your tomatoes. When composting, the recommendation is to use three parts “brown” material (dried leaves, straw), with one part green material (fresh veggie trimmings, grass clippings). You can rotate your compost by buying a rotating compost bin, or simply by using a shovel and mixing it up. After 6-9 months, it will turn dark brown and be usable as an additive or soil for your tomatoes.

Eggshells to avoid blossom end rot

Blossom end rot is one of the most common (and most disappointing) symptos of calcium deficiency in tomatoes. You will notice a visible blackening or rotting on the bottoms of the fruit. Adding eggshells to your tomato plants is a great way to reduce the chance of blossom end rot, and eggshells also provide potassium and phosphorus. 

You can use eggshells as a plant food by allowing them to dry outside in the sun for a couple days, or drying them in the oven by roasting at 200 degrees F for 10 minutes. 

Then, crush the eggshells up with your hands or in a food processor. When you are transplanting your tomato plants, put a handful of crushed eggshells in the hole before setting the root ball of the plant.

You can also sprinkle your crushed eggshells on top of the soil near the base of the plant later in the season to add much-needed calcium and other nutrients.

Coffee grounds for nitrogen

Like magnesium, a nitrogen deficiency is another common cause of chlorosis in tomatoes. Nitrogen deficiencies can be caused or made worse by imbalance pH levels in your soil, not enough organic matter, or droughts. 

Luckily, coffee grounds are a great source of nitrogen for plants, and are likely a form of waste you are already producing with your morning cup of joe!

To fertilize your tomato plants with coffee grounds, just sprinkle the grounds all around the soil your tomatoes live in, and lightly rake them into the soil. 

Alternatively, you can create a liquid tomato fertilizer by mixing brewed coffee with water, allowing it to sit overnight, and watering your plants with the diluted coffee. You can also add coffee grounds to your compost to make it more nitrogen-rich.

Wood ashes

If you have a wood-burning fireplace or a fire pit in your backyard, save those ashes! They are a tasty treat for tomato plants. Wood ashes contain calcium, magnesium, and potassium, which helps prevent vitamin deficiencies and improves the quality of quantity of fruit.

The safest way to create potassium-rich wood ash fertlizer is by adding it into your regular compost. Ash can produce lye and salt when it gets wet, which, if in great enough quantity, quill burn your tomato plants. When you compost your wood ash first, the lye and salt leaches away and it is less likely to harm your plant.

You can also sprinkle wood ash lightly around the soil of your tomatoes, but be sure to use it sparingly.

Fertilizer tea

Fertilizer tea is a buzzword in the gardening community, and can add much-needed nutrients to your soil. But there is conflicting information around what fertilizer tea actually is. Is it a special form of brewed tea leaves (like the tea we drink?)

Or is it a brewed version of compost or yard clippings that is made especially for plants?

The tea we drink has high levels of potassium, phosphorous, and nitrogen, but after brewing those percentages drastically decline. It is unlikely that you will notice an improvement in the health of your tomato plants by watering them with tea. 

Compost tea is another common fertilizer for tomato plants, and is usually what people mean when they refer to “fertilizer tea”. The liquid nature of it is great for microbial growth, and provides your plant with readily-available nutrients.

To make compost tea, add a ratio of 1:20 of compost to water to a large bucket and vigorously stir it. Stir it daily and allow it to sit for 1-2 weeks. Filter out the solids of the compost with a cheesecloth or strainer, and apply it to the soil around your tomato plants.

Tomatoes are nutrient hogs, so it’s likely that you’ll need to supplement with plant food throughout the season. But that doesn’t necessarily mean that you have to buy expensive fertilizers — you can make natural homemade plant foods from a variety of different common materials, to provide your plant with many of the nutrients it craves.

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