Fertilizing your cactus will cause it to grow more, and become healthier. This will add “thickness” to the plant by increasing the growth of cells in the body of the cactus.
As a result, your cactus will be bushier and have more flowers than if you don’t fertilize at all.
How Often Fertilize Cactus?

A cactus goes through a growing period and a dormant period. It would help if you fertilized your cactus plan during its growth period. That means fertilize your cactus during the spring, summer, and fall growing seasons.
If your cactus grows during the winter, begin the fertilizing routine during late fall, winter, and spring. You will want to fertilize a cactus once per season, so feed your cactus plant three times per year.
Why Fertilize Cactus?
Cactus plants and succulents can absolutely survive without needing fertilizer. They need very little water or fertilizer in general. That makes them require little maintenance; still, like other plants, cactus will benefit from fertilizer.
Fertilizer can help promote the healthy growth of your plant. It can make the cell walls stronger and the root system more robust.
Nutrients will bring more brightly colored plants as well. Plus, certain fertilizers can encourage your cactus plants and succulents to flower.
What To Use to Fertilize a Cactus?

Cactus plants will benefit from a highly diluted fertilizer. Because cacti and succulents have adapted to desert areas, fertilizing without first diluting can cause root and stem “burn.”
The desolate environments in which they have adapted make them highly resilient and need little outside help as they are prolific at conserving water and nutrients.
Cactus plants need fertilizer that is low in Nitrogen content and high in Phosphorous content. All fertilizers come with three numbers that correspond to the levels of Nitrogen (N), Phosphorous (P), and Potassium (K) in the fertilizer.
When choosing a fertilizer for your cactus, use one with a 5-10-5 N, P, K count for optimal results. However, it is OK to use an all-purpose fertilizer.
Always dilute any fertilizer you are using on your cacti to one-quarter of the recommended amounts.
For example, if your fertilizer says to use one cup of fertilizer to one gallon of water, you should use a one-quarter cup of fertilizer. Be sure to blend fertilizer evenly into the water for even distribution throughout the soil.
Many brands make cactus-specific fertilizers. These are a great option. Specifically, one that is slow-release.
A slow-release cactus fertilizer will spread out the feeding slowly over time. This is ideal for allowing your cactus plant to adapt to a fertilizing routine.
How To Get Cactus Plants to Flower with Fertilizer?
If you want to see your cacti and succulents make beautiful flowers and it has not yet, consider adding ammonium sulfate.
The best time to do this is during the spring when it is coming out of its dormant period and beginning its growing season.
Simply add the powder to the water during your regular watering schedule and wait for the blooms.
Make sure you do this at the right time of year. There is no point in adding it during the winter or late in the season.
Most gardening stores do not sell this, but it is easy to get online. You will be amazed at how well this works.
What To Do if Your Cacti Are Over-Fertilized?

If you accidentally spill fertilizer or perhaps you messed up your math, your plant may experience some very negative results.
They will experience root and stem burn, or they can even die. If you have over-fertilized your cactus, make sure to attempt to flush it out.
This can be tricky because cacti do not like a lot of water. However, you will increase the chances of your plant bouncing back if you do this. Pour lots of water into the soil to attempt to wash away the fertilizer.
Suppose you can see the fertilizer on the soil because perhaps you spilled some. Scoop out what you can, even if that means removing some of the soil. You can easily replace soil. It is much more difficult to eradicate over-fertilized plants.
Conclusion
Cacti and succulents are some of the most resilient plants on the planet. While they do not necessarily require fertilizer, they will greatly benefit from it.
Any plant will benefit from some care and attention. That means fertilize and water to meet the specific needs of your plant.