Cacti & Compost

Benefits of Compost

• Compost is a result of the decomposition of organic material and is teeming with beneficial bacteria, microbes, fungi and other microscopic life forms that aid in decomposition, fight pests and crowd out disease-causing pathogens. Among the many nutrients found in compost are nitrogen, potassium, phosphorous, calcium and sulfur. In addition to adding beneficial nutrients to the soil, compost can improve soil structure. Cacti are highly susceptible to root rot and benefit from the improved drainage of soil amended with compost.

Components of Compost

• The ingredients of compost are called feedstocks, and they are quite varied. Most home-composters stick to items that are not protein-based. These include yard waste like leaf litter, grass clippings, spent annual flowers and debris from the vegetable garden. Other nonprotein compost items include kitchen scraps, like leftover salads, fruit and vegetable peels and eggshells. Animal matter like meat, eggs, butter or milk are only composted by experienced gardeners due to the risk of introducing bacteria like E. coli and salmonella into the soil.

Potted Cacti

• Creating the ideal growing medium is especially important for potted cacti. Their roots only have limited space to grow and only have the nutrients available that you provide for them. While peat is often recommended for potted cacti, Ron Payne from the Newfoundland Horticultural Society says that peat is actually detrimental to the health of cacti. Peat decomposes quickly, he says, and leaves the cactus sitting in a sticky goo devoid of oxygen. Instead, Payne recommends a mixture of equal parts coarse sand, well-tilled garden soil and leaf compost for growing healthy potted cacti.

Cacti in the Ground

• Compost is beneficial for cacti planted in the ground, as well. Cacti planted directly into sand have little chance to absorb water and nutrients from the soil before they drain away. Amend sandy soil with organic compost to improve water and nutrient retention. The University of Arizona recommends the soil where you plant your cacti should be 25 percent compost. If your soil is heavy with clay, water won't drain through it at all, and you run the risk of root rot. Amend your soil with compost and pumice to improve drainage.