Cactus is an excellent choice for those of us who need plants that require little care or handling. They come in a variety of shapes, sizes and colors and, when in bloom, display some of nature's most beautiful flowers. While care for cacti is relatively easy, its a good idea to use soil that will best accommodate the specific physical and nutritional requirements your plant needs to thrive.
Stems of most cacti are usually soft, thick, and succulent, storing water for dry periods and are covered with a waxy surface that prevents moisture loss. The stem will take up water from the roots very quickly.
Most cacti are covered with spines that help protect the plant from animals that might try to eat them. Some cacti have spines that also reflect light away from the plant or direct water to the roots.
Cacti usually have very shallow root systems that spread out to take advantage of brief periods of rain. Cactus roots branch thoroughly, working their way through dry, hard, and sometimes rocky soil.
Soil Requirements for Cacti
Cacti prefer soil that wets easily and drains well. They will, however, not grow in pure sand. Sand has absolutely no nutritional value for cacti. Some organic material is necessary for proper nutrition and to provide air in the soil. However, the soil should not be so rich that it holds water for long periods. This will inevitably rot the roots of the plant.
Cacti also prefer alkaline soils that have a high calcium level. Bone meal or lime can be added to the soil to meet this requirement. Test the pH, from time to time, and amend the soil as needed.
Clay pots are preferable for planting cacti because they allow the soil to dry out completely between waterings. Pots should also have good drain holes to help keep water from pooling.
Homemade Soil for Cacti
Soil for cacti can be prepared at home. While no soil mix is perfect in all situations for all plants, a good, standard soil recipe for cactus is 20 percent top soil to 10 percent peat moss to 70 percent pumice or vermiculite. Add a half cup of bone meal for every 12 quarts of soil mix to ensure a proper pH balance. A time release fertilizer, such as Osmocote® is also recommended.
Sterilize the soil mix prior to planting to remove any diseases. This can be done by placing the soil mix in a plastic bag, inserting a cooking thermometer into the soil through the bag, and heating the soil to 165 degrees Fahrenheit in your oven for 30 minutes.