Rebutia senilis
| Light | Bright light with some direct sun; a little shade from the fiercest summer afternoons |
|---|---|
| Water | Regularly in the growing season once the mix has dried; keep dry and cool in winter |
| Soil | Fast-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; a cold, dry winter rest suits it — roughly USDA zones 9–11 |
| Propagation | Offsets (very easy); also seed |
| Toxicity | Non-toxic to cats and dogs |
Rebutia senilis is a small, clumping cactus from the mountains of northern Argentina, densely clothed in fine, bristly white spines and famous for a spring display of large, brightly coloured flowers. The species carries so many blooms at once — in shades of red, orange, yellow or pink depending on the clone — that a well-grown clump can almost vanish beneath them, which has made it a long-cultivated favourite among beginners and collectors alike. It belongs to the genus Rebutia, a group of dwarf South American cacti prized for exactly this kind of generous, easy flowering.
Description
Rebutia senilis forms low, flattened-globular stems that offset freely from the base, in time building up into a broad cushion of many heads. Each stem is only a few centimetres across and is covered in numerous fine, bristly, glassy-white spines that radiate outward and give the plant its whiskery, pale appearance — the source of the epithet senilis, "old man" or "aged". The spines are slender and bristle-like rather than stout, though under strong sun they lengthen and stiffen and can still prickle.
The flowers appear in a flush in spring, emerging in a ring low down around the sides of the stems rather than from the crown. They are relatively large for the size of the plant, funnel-shaped, and open widely in sunshine over several days. Flower colour is variable across the many named forms in cultivation, spanning vivid red, orange, yellow and softer pink tones.
Distribution and habitat
The species is native to the Andean foothills of northern Argentina, particularly the province of Salta, where it grows at altitude among rocks and grasses. Plants there experience strong sun, sharp drainage and a distinctly cold, dry winter — conditions worth keeping in mind when growing it, as that seasonal cold-and-dry rest is what triggers the heavy flowering.
Cultivation
Rebutia senilis is one of the easiest cacti to grow and flower, which is a large part of its enduring popularity. Give it a free-draining, largely mineral mix and a position in bright light with some direct sun; a little relief from the hottest afternoon glare in summer keeps the body from scorching. Through the growing season water fairly generously whenever the mix has dried out, then reduce and stop as autumn arrives.
The key to a good flowering is a cool, dry winter — keep the plant almost completely dry and, if you can, cold (though frost-free) from late autumn until growth resumes in spring. Plants kept warm and watered through winter tend to grow soft and flower poorly. See Watering and Repotting for general technique; the species clumps quickly and appreciates potting on into a slightly wider pan every couple of years.
Propagation
Because the plant offsets so readily, the simplest method is to detach a few of the pups, let the cut surfaces dry for a few days, and pot them up in the same gritty mix — they root quickly. See Propagation — offsets for details. The species also comes easily from seed, which germinates readily on a warm, mineral surface kept humid; seed-raised plants show the variation in flower colour for which the species is known. See Propagation — seed.
Common problems
- Rot — the usual cause of loss, almost always from a wet winter or a slow-draining mix; stems soften and discolour from the base.
- Shy flowering — nearly always down to too little light or a warm, watered winter that skips the necessary cold, dry rest.
- Etiolation — insufficient light makes the stems grow tall, pale and soft instead of tight and rounded.
- Pests — red spider mites and mealybugs (white fluff between the stems and in the spine mass) are the common offenders; see Pests and diseases.
See also
- Rebutia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — offsets · Propagation — seed · Pests and diseases