Leuchtenbergia - Agave Cactus, Prism Cactus

DESCRIPTION: There is only one species in this group. L. principis (Agave Cactus; Prism Cactus) is a very slow-growing cactus from Mexico. This plant has a large, tuberous taproot and a cylindrical shaped stem that becomes bare and corky at the base with age. It has long, slender, grayish-green tubercles, which look like a rosette of leaves. The tubercles have puplish-red blotches at their tips and are topped with papery spines giving it the appearance of a miniature Agave, thus the common name. Old, basal tubercles usually dry up and fall off. After many years, this plant can eventually grow up to 2 feet high. After 4 or so years, yellow, funnel-shaped flowers are borne at the tubercle tips. These are followed by smooth, green fruits.

POTTING: The Agave Cactus needs a minimum temperature of 42º to 48º F and full sun. It should be planted in a deep flowerpot in order to hold its large taproot. Grow in rich, porous, sandy soil and let the soil dry out between waterings. Repot in the spring when their roots become cramped. Generally, they should be repotted every other year in order to provide fresh soil. However, this doesn't necessarily mean they'll need larger containers. Fill about a quarter of the pot with broken crocks, gravel, etc. to promote good drainage. Firm the potting soil. After repotting do not water for a week or more.

PROPAGATION: This plant may be increased by taking cuttings, sowing seeds, or planting any offsets. Seeds may be sown in containers filled with general-purpose cactus and succulent potting mix. Sprinkle the seeds evenly over the surface of the compost. Cover the seeds lightly with some grit, moisten the container and place in an area with high humidity and warmth. Transplant the seedlings when they're large enough to handle. Waiting too long until they are overcrowded can cause rot. Gently separate them so as not to damage the delicate roots. Transplanting will be easier if the soil is slightly moist. Seedlings can be potted singly or with several to a pot. They seem to do better if a few are grown together than by themselves. Single tubercles can be used as cuttings and encouraged to take root, though it isn't easy. Cut off a tubercle with a sharp, sterile knife. Leave the cutting in a warm, dry place for a couple of days to allow a callus to form over the wound. Once the callus forms, the cutting may be inserted in a container filled with firmed cactus potting mix topped with a surface layer of coarse grit. They should be placed in the coarse grit only; this prevents the cut end from becoming too wet and allows the roots to penetrate the rich compost underneath. The cutting should root within 2 to 6 weeks.

VARIETIES: L. principis.

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