Tephrocactus alexanderi 'Geometricus' syn. Tephrocactus geometricus

Only a select few cactus will survive outside in temperate climates, because of winter rains and low temperatures. In selecting plants for use outside, one must look at the habitat from which the plant originates. It must have sun most of the day. Morning and afternoon sun is better than two o clock sun. The area should have very good drainage, this is more important in the winter than the summer. Most cactus are not killed by the cold, but when the water inside the plant freezes it expands and splits the outer layer of skin, this allows bacteria to enter the plant and kill it.

Many species can also be grown from seed; Use John Innes No 1 with added grit or sand for added drainage. Sow the seed in spring. Large seed will need a covering of one to two times the depth of the size of the seed. Small fine seed should not be covered, but mix the seed with a little sand to help with an even distribution. Water with a misting bottle or a watering can with a fine rose and cover the pot with a sheet of glass or plastic bag. Keeping them at 21°C in partial shade. Allow air into the pot daily by removing glass or plastic bag and wiping off condensation. Keep moist but not overly wet. Pot on seedlings when they are big enough to handle. It can take up to 12 months for them to reach this stage.

Potting mixes can be made by mixing one part potting mix, one part washed sand & one part course fill (rocks, pumas, broken pots, etc.) Don`t worry too much drainage is better than not enough. When planting the cactus never dig a deep hole down in the potting mix. You want the plant to set on top of the potting mix, this allows the roots to go down to get moisture with out the plant setting in wet soil. A potted cactus will live and flower in the house if given enough light, place the plant near a bright lighted window, where it will receive light most of the day. On the patio is different place the cactus in a partly shaded area until it become accustom to the sun.

Tephrocactus cacti naturally grow and form segments, and they can be propagated using these segments. The segments can be broken off and will root, although the time taken to root will depend on the conditions and the species. Once your plant has gained a decent size and has grown a number of segments, carefully remove a piece and allow it to callous over for a couple of days. Depending on the size of the cut area, a callous will form over the cut surface. Once the callous has formed, place the segment in a pot with a potting soil mixture and keep in a warm place until new roots emerge. Alternative methods of propagation, such is seed, is better for solitary growing species.