Chamaecereus silvestrii
| Light | Bright light with some direct sun; a little shade from harsh summer afternoon sun |
|---|---|
| Water | Regularly in spring and summer once the mix dries; keep cold and dry in winter |
| Soil | Fast-draining, gritty mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing in growth; tolerates a cold, dry winter rest in USDA zones 9–11 |
| Propagation | Cuttings and offsets (very easy); seed and grafting also possible |
| Toxicity | Non-toxic to cats and dogs |
Chamaecereus silvestrii — now more correctly placed as Echinopsis chamaecereus — is a low, sprawling cactus from the mountains of Argentina, universally known as the peanut cactus. It forms dense clusters of short, finger-like, pale-green stems that branch freely, sprawl over the pot rim and root wherever they touch soil, and in spring it is smothered in vivid orange-red flowers. Undemanding, fast to multiply and quick to bloom, it is one of the classic beginner's cacti and a longtime windowsill favourite. It belongs to the genus Echinopsis.
Description
The peanut cactus produces a low mound of soft, cylindrical stems, each roughly the size and shape of a peanut or a stubby finger — commonly 1–2 cm thick and a few centimetres long before a new joint branches off. The stems are a fresh light green, ribbed lengthwise, and set with short, soft, bristly white spines that are harmless to handle. Individual joints break away easily, which in the wild helps the plant spread vegetatively as fragments roll away and root.
In spring, and often again in early summer, mature clusters throw out a profusion of funnel-shaped flowers in a brilliant scarlet to orange-red, each bloom several centimetres across and opening for a day or two. The sheer quantity of flowers over an established clump is the plant's great appeal.
Distribution and habitat
Chamaecereus silvestrii is native to the mountains of Tucumán and Salta provinces in northwestern Argentina, where it grows at moderate to high elevation among rocks and grass. Its montane origins make it noticeably more cold-tolerant than many lowland cacti: given a dry substrate it shrugs off cool winter nights that would harm more tender species. In the wild it is known essentially only from its original 1896 collection; later expeditions failed to relocate it, and its status in habitat is uncertain — it may be extinct in the wild. In cultivation, however, the plant has been passed hand to hand for well over a century and is now grown all over the world, the bulk of cultivated stock apparently descending from a single clone.
Cultivation
Few cacti are easier. Grow the peanut cactus in a free-draining, mostly mineral mix in a wide, shallow pot that gives the clustering stems room to spread. Give it bright light with some direct sun — enough to keep the stems compact and to encourage heavy flowering — while easing off the fiercest afternoon glare in high summer, which can scorch the soft joints.
Water freely through the growing season once the mix has dried, then withhold water almost entirely through winter. A cold, bone-dry winter rest is the key to a good spring display: kept cool and dry the plant sets abundant flower buds, whereas a warm, watered winter tends to produce lanky, bloom-shy growth. It is a fast grower and will happily fill and overflow its pot, so plan on regular repotting. See Watering for general technique.
Propagation
Propagation could hardly be simpler. The stem joints detach at the slightest knock; lay a broken segment on dry mix, let the cut end callus for a few days, and it will root within a week or two — see Propagation — cuttings and Propagation — offsets. Because the plant is so free-branching there is always spare material to share. It can also be raised from seed, though the common cultivated clone is self-sterile and rarely sets seed on its own. Named or delicate forms (such as the yellow "Lutea" sport, which lacks chlorophyll) must be maintained by grafting onto a green rootstock since they cannot survive on their own roots.
Cultivars
Several colour sports and hybrids exist. The best known is the golden-yellow "Lutea" (sometimes sold as the "yellow peanut cactus"), a chlorophyll-deficient form kept alive by grafting. The species has also been crossed with larger-flowered Echinopsis and Lobivia relatives to produce free-blooming hybrids in a wider range of flower colours, while retaining the easy, clustering habit of the peanut cactus.
Common problems
- Etiolation — too little light makes the joints thin, stretched and dark, and greatly reduces flowering; move to a brighter spot.
- Rot — soft, browning stems usually follow winter wetness or a poorly draining mix; keep the plant dry and cold when dormant.
- Pests — red spider mites can bronze the stems in hot, dry air, and mealybugs may hide among the crowded joints and roots.
See also
- Echinopsis — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Propagation — offsets · Repotting