What Is Mild Cactus Fertilizer?

Houseplant vs. Cactus Fertilizer

• Houseplant fertilizer is usually much stronger than fertilizer that is designed specifically for a cactus plant. Each ounce of houseplant fertilizer contains far more nutrients than each ounce of cactus fertilizer. That is because a cactus plant needs far fewer nutrients than most other types of houseplants. In fact, a dose of too many nutrients at one time can be harmful to a cactus, which is why it is not a good idea to fertilize a cactus in the same way as other plants.

Dilution

• Although houseplant fertilizer is not ideal for a cactus plant when it is full strength, it can be diluted to create a mild cactus fertilizer. Mix the fertilizer according to the manufacturer's directions, and then dilute it by combining equal amounts of mixed fertilizer and water. This dilution creates a mild cactus fertilizer that will give the plant the correct amount of nutrients without harming it.

Nutrients

• Although cactus plants have low nutrient requirements and need only occasional fertilizing, they do need some phosphorus. If you're using a diluted houseplant fertilizer instead of a mild cactus fertilizer, look for one that has a higher concentration of phosphorous than nitrogen. The numbers on the package indicate the amounts of the different nutrients. The first number indicates the amount of nitrogen, the second phosphorous and the third potassium. For cactus plants, look for a fertilizer in which the second number is larger than the first.

Application

• Due to their low nutritional needs, cactus plants do not need frequent or regular fertilization. Fertilize once or twice per year with a mild cactus fertilizer or a diluted houseplant fertilizer. Cactus should not be fertilized during the winter. Once in the spring, and again in either midsummer or late in the summer when most growth is occurring, are the proper times to fertilize.