I recently attended a talk at Mercer on growing cactus and succulents in Houston. If you haven’t attended any talks at Mercer do consider it. They’d love to see you and I learn a great deal each time I attend.
Most cactus prefer drier environments than we have in Houston. While they all prefer it dry, not all of the cactus and succulents enjoy our heat. Winter rains are the biggest threat to cactus growing here. Wet and cold together will cause many cactus to rot.
Cactus and succulents differ only slightly. All cactus are succulents, not all succulents are cactus. Cactus store water in their stem, succulents store water in the leaves, stem or both.
Cactus have tufts of hair or small spines at the base of every spine, succulents do not. While you can strip a cactus bare of spines with out hurting the plant. It is similar to leaf removal. You can not do so with a succulent. Succulent thorns are connected to the stem tissue. Removing them will tear the stem that transports nutrients through the plant.
Cactus have spines which are leaves which have evolved to a more efficient shape for the climate. The spines offer protection from critters looking for water in the desert and also provide shade for the plant. The more spines on a cactus the more sun it likely needs.
Some succulents have roots that spread along the surface to collect water, some use tap roots to find deep water.
Cactus originated only in North and South America, succulents are found worldwide.
Sand and or soil mixed with larger rocks/mulch or other material that will let water drain works best as a planting medium. Be sure to slope and raise the bed to keep water from collecting near the plants.
Mealy bug occasionally bother succulents, treat with insecticidial soaps. Fire ants will some times build a mound right over your succulent, burying it. Treat them with your favorite fire ant treatment.
Succulent gardens look best and least annoy your neighbors and the homeowners associations when you use several plants of different heights, textures and colors together. Try to use one or a few large plants, then fill in with smaller plants. Also include some dry plants that aren’t succulents. Wild flower bunches blend well. The Succulent gardens pool at Flickr has a nice collection of photos for ideas.