5 DIY Cactus Fertilizer Recipes for Better Growth

Cacti have low watering and fertilizer needs making them easy to care for as houseplants. However, they require a boost for healthy growth and better flowering. The easiest way is to use homemade fertilizers, which are safe to use on plants and around children and pets.

When using commercial cactus fertilizers, there is always the fear of burning the plant or harming animals. DIY fertilizers are also affordable because most of them are made from materials or by-products readily available in our homes. 

DIY cactus fertilizer recipes

Here is a list of homemade fertilizers for cactus and how to use them correctly.

1. Banana peel water

Banana peel water is an excellent supplement to traditional houseplant fertilizers. When soaked in water, they release essential nutrients that promote plant growth. This includes potassium, calcium, magnesium, and phosphorus among other minerals.

How to make and use

1. Chop banana peels, preferably green ones, into small pieces. 
2. Soak them in water for 2 to 3 days.
3. Strain the soaked banana peels from the water. You may discard the used peels or use them in compost.
4. Apply the water on your cactus occasionally. 

Aim to fertilize your cactus with banana peel water once a week during the growing season. Do not overwater your plant as it can cause root rot and other fungal problems. 

2. Worm casting tea

Worm compost is made by steeping worm castings (worm manure) in water. It is a powerful organic fertilizer and soil conditioner. The benefits of worm casting tea are many. It contains essential nutrients like nitrogen, phosphorus, potassium, calcium, and magnesium.

The tea is also a source of beneficial microbes that can help improve soil health. This includes breaking down organic matter, improving drainage, and aerating the soil. Using the worm casting tea on cacti can therefore enhance better growth and flowering.

How to make and use

1. Fill a bucket with 1 gallon of water (use rainwater, pond, or distilled water).
2. Place the worm castings in a mesh bag or cheesecloth and tie it closed.
3. Place the mesh bag or cheesecloth containing worm castings in the water.
4. Let the worm castings sit in the water overnight.
5. Remove the compost bag and pour the mixture into a spray bottle.
6. Dilute the worm casting tea with some water in a ratio of 1.3. 
7. Use the worm casting tea immediately to water your plants. Be sure not to overwater your plants.

3. Coffee grounds

Coffee grounds are a great source of nitrogen, potassium, phosphorus, and essential micronutrients beneficial to cactus plants. When used correctly, they can also help acidify the soil, improve its structure, and enhance drainage and aeration. 

As you know, cacti thrive in well-draining soil. Adding coffee grounds directly can cause soil compaction. This means, your soil will retain excess moisture which is likely to cause root rot. So, the best way to use coffee grounds is by adding them to compost first.

This allows microorganisms to break down the nutrients, making them more accessible to plants. However, do not use more than 20-35 percent by volume of coffee grounds in a compost pile for proper decomposition.

How to prepare and use

Add a thin layer of your well-decomposed coffee ground, preferably not over 1/2 inch thick. Ensure they are not in direct contact with the plant stems. Water your cactus as usual after the application. Use every 3-4 weeks during the growing season in spring and summer.

Coffee grounds can also be used as a liquid fertilizer. Mix 1 cup of used coffee grounds with 2 gallons of water and let it steep overnight. Apply the tea as a liquid houseplant fertilizer on your cactus. Don’t use the same week with your regular houseplant fertilizer.

4. Eggshells

Egg shells contain calcium which can help cactus develop strong stems. They can also help aerate the soil, reduce compaction, and improve drainage. However, they should be used correctly to avoid any negative effects like spreading harmful pathogens.

How to prepare and use

1. Rinse eggshells thoroughly to remove any pathogens and residue.
2. Let them dry completely to prevent mold growth.
3. Crush them into small pieces or grind them into powder using a blender or mortar and pestle.
4. Mix the crushed shells into the soil or sprinkle them on top of the soil around your succulent. 

You can also boil eggshells in water for about 5–10 minutes and use the calcium-infused water to fertilize your cactus.

Note: Eggshells take time to break down. They should be used as a long-term supplement rather than an immediate fertilizer. Using excessively can also alter the soil pH too much.

5. Epsom salt solution

Epsom salt (magnesium sulfate) is beneficial for cacti when used correctly. It provides magnesium and sulfur. These two essential nutrients can support healthy growth, improve photosynthesis, and enhance flower production, especially in the Christmas cactus.

Magnesium in particular is crucial for chlorophyll production. If a cactus has magnesium deficiency, you may notice yellowing or weak growth. Epsom salt can help correct this. However, too much magnesium can interfere with calcium and potassium uptake.

How to use

1. Dissolve 1 teaspoon of Epsom salt in one gallon of water.
2. Pour into a spray bottle and mist the cactus lightly.
3. Do this once a month during the growing season in spring and summer.
4. Do use Epsom salt the same week you applied your regular cactus fertilizer.

Final thought

DIY cactus fertilizers can incredibly boost the growth and flowering needs of your cactus and other houseplants. Some of the most effective homemade cactus fertilizers to use include banana peel water, worm casting tea, coffee grounds, eggshells, and Epsom salt solution.

Like the standard fertilizers for cactus and other succulents, apply your homemade feeds during the growing season in spring and summer. What’s important, use them occasionally without overwatering. Results can take some time, so you need to be patient.