Care of Potted Cactus

Soil

• Cactus soils require three elements for the plant to thrive. Horticultural grade sand and grit are required for good drainage. The sand must be horticultural grade because fill sands contain undesirable materials like salt. For grit, horticultural pumice is ideal, but may be difficult to find. Pearlite or porous gravel also make good grit materials. Although peat-based compost is often recommended as a third soil element, it may contribute to pests like mealybugs. Sifted commercial potting mix is a better compost soil for cactus plants. Blend these components by mixing one-third each compost, sand and grit.

Water and Fertilizer

• Although cacti can survive dry conditions, they won't thrive without regular water and fertilizer during growth periods, which for most cactus plants are from spring to early fall. Many cacti go into a dormant period in late fall when daylight is limited and in mid-summer when temperatures are highest. Growing cacti should be watered at least once a week by soaking the soil until the water runs out the drainage holes in the bottom of the pot. A 10-10-10 fertilizer diluted to about one-quarter strength should be added to the water each time. During dormant periods, water only when the soil becomes dry and don't fertilize during this period.

Light

• Most species of cacti thrive in bright light, but not all can tolerate direct sunlight and high temperatures. If your cactus is getting too much light, it will appear discolored or bleached; it may turn yellow to orange in some places. Move to an area with less light. If the color doesn't improve, your cactus may be suffering from other problems such as disease or over-watering. If a plant isn't getting enough light, it may begin to look leggy because of a process called etoliating. Transition the plant slowly to brighter light. If you change conditions rapidly, the plant may become scorched.

Pests

• Although cacti are a hardy species, they're still vulnerable to some types of plant pests. Mealybugs weaken cacti by attacking the root system. Minor infestations can be removed by dabbing the individual bugs with a cotton swab dipped in rubbing alcohol. If your cactus appears stressed but you see no bugs, take the plant out of the pot and wash the soil off of the roots. Soak in an insecticide according to the label directions and re-pot in new soil. Scale bugs, which show as raised brownish spots, can be eliminated using the same method. Spider mites, another concern, can be detected by a whitish web spun close to the surface of your cactus, which then will develop yellow spots and later turn a rust color. Mist the plant to eliminate spider mites. For a severe infestation, miticides can be effective.