Cactus Potting Mixture Recipe

Soil Qualities

• Most cactus plants require quick-draining soil that retains very little moisture, otherwise the roots begin to rot. They usually aren't heavy feeders so very little organic matter is needed for healthy growth. Some tropical cacti, like the Thanksgiving cactus (Schlumbergera truncata, United States Department of Agriculture plant hardiness zones 10 to 12), prefer slightly moister conditions, so they can tolerate more organic matter in their potting mix. The cactus pot, which must have at least one bottom drainage hole, also supplies some of the necessary drainage when combined with the proper soil recipe.

Ingredients

• The ingredients for a cactus soil mix can vary slightly, depending on your preferences and what you have on hand. The mix begins with organic matter like sterile garden soil or ground fir bark. Shredded peat moss provides further structure to the mixture, while perlite, coarse sand or vermiculite ensures quick drainage. Most of these ingredients have very few available nutrients. Fertilizers and amendments provide the initial nutrients the cactus needs to grow.

Mixing

• You can make just enough soil for a single pot or a large batch for several containers. Mix equal parts of the peat, soil or bark, and the drainage material together. To ensure proper nutrient availability, mix in 8 tablespoons dolomitic lime and 6 tablespoons superphosphate for every bushel of the recipe. Adding 3 tablespoons 10-10-10 fertilizer, 1 tablespoon iron sulfate, and 1 tablespoon potassium nitrate per bushel provides all the nutrients the cactus needs. Mix up the potting soil just before you use it, or make extra and store it in a sealed container for later use.

Planting

• Even the best potting soil recipe cannot help your cactus plant if it's not watered correctly. When planting in the mix, put some in the planting container and add only enough water to barely dampen it. Allow excess water to drain from the bottom holes in the pot for 30 minutes, then plant the cactus at the same depth it was growing at previously. Empty any water that collects in the drainage tray beneath the pot promptly so the potting mix doesn't reabsorb it. Most cactus plants require watering when the soil is almost completely dry, except for tropical cacti, which require watering when the top 1 inch of soil feels dry.