Pachycereus weberi
| Light | Full sun; give the strongest light you can |
|---|---|
| Water | Regularly in the warm growing season; keep dry and cool in winter |
| Soil | Deep, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Warm-growing; protect from hard frost, USDA zones 9b–11 |
| Propagation | Seed; large branch cuttings |
| Toxicity | Not known to be toxic to cats or dogs |
Pachycereus weberi is a massive, tree-like columnar cactus from southern Mexico, and one of the largest cacti in cultivation. Mature plants develop a short, stout trunk that branches into a broad, many-armed candelabra of arching, blue-green stems, so that an old specimen can look more like a spreading tree than a cactus. It was long known by the synonyms Lemaireocereus weberi and Cereus weberi, and is sometimes sold under the common name candelabro.
Description
Pachycereus weberi is a giant of the family, capable of reaching the size of a small tree over many decades. A young plant grows as a single column; with age it forms a distinct woody trunk that divides into numerous heavy branches, which in turn curve upward to build the characteristic candelabra crown. The stems are thick and strongly ribbed, and their surface carries a glaucous, blue-green bloom that is one of the plant's most attractive features.
The areoles along the ribs bear stout, stiff spines — a longer central spine with several shorter surrounding ones — dark when young and weathering to grey with age. Large, funnel-shaped flowers open at night in the warmer months, cream to pale in colour and rather waxy in texture; they are followed by spiny, rounded fruit. Because the plant must reach considerable size before it flowers, blooming is mostly seen on old, established specimens in the ground.
Distribution and habitat
The species is native to southern Mexico, where it grows in hot, seasonally dry tropical scrub and thornforest in states such as Oaxaca and Puebla. It is a conspicuous element of these landscapes, standing above the surrounding vegetation on rocky slopes and in open valleys. Like the rest of the cactus family it is listed under CITES Appendix II; nursery-grown plants and cuttings are freely and legally traded, while collecting from wild populations is not.
Cultivation
For a plant of its eventual size, Pachycereus weberi is straightforward and vigorous. Give it the brightest position available — full sun suits it — and a deep, very free-draining mostly mineral mix, because the plant becomes tall and top-heavy and appreciates root room to anchor itself. Unlike many desert cacti it is a genuinely thirsty grower in warm weather: water generously while it is in active growth and the soil is drying between waterings, then taper off and keep it dry and cool through winter to prevent rot.
It is fast-growing by cactus standards and can be raised in a large container for years, though it will only approach its full stature when planted out in a frost-free climate. Protect it from hard frost; brief light chills are tolerated by established plants but young ones are more tender. See Watering and Repotting for general technique.
Propagation
The species is grown from both seed and cuttings. Seed germinates readily with warmth and humidity, giving many plants at once, though seedlings take a long time to reach any size. Large branch cuttings offer a much quicker route: sever a healthy arm, let the cut face dry and callus for a week or more in shade, then set it in a gritty mix to root. Handle the heavy, spiny stems with care.
Common problems
- Rot — the main risk, from cold-and-wet conditions or a poorly draining mix; keep the plant dry in winter and give it fast drainage.
- Toppling — tall potted plants become top-heavy; use a deep, weighty pot and stake if needed until the roots take hold.
- Pests — mealybugs (white fluff in the areoles) and scale can settle on the ribs; watch the growing tips and stem joints. See Pests and diseases.
See also
- Pachycereus — the genus overview
- Soil and potting mix · Watering · Propagation — cuttings · Repotting