Parodia scopa
| Light | Bright light with some direct sun; a few hours of shade from the fiercest afternoon summer sun |
|---|---|
| Water | Regularly in the growing season once the mix has dried; keep dry and cool in winter |
| Soil | Free-draining mineral-rich mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9–11, tolerant of a cool dry winter |
| Propagation | Seed (primary); occasional offsets |
| Toxicity | Non-toxic to cats and dogs |
Parodia scopa is a small, globular to shortly columnar South American cactus wrapped in fine, silvery-white radial spines, frequently accented by contrasting reddish or brown central spines, and crowned in early summer with glossy, bright yellow flowers. Long grown under the name Notocactus scopa, it remains one of the most beloved and forgiving of the "ball cacti", earning the common name silver ball cactus for its soft, woolly-looking coat of spines. It belongs to the genus Parodia.
Description
Parodia scopa begins life as a neat green globe and slowly lengthens into a short cylinder, typically reaching around 10–25 cm tall and up to about 10 cm across in cultivation, sometimes offsetting from the base in age. The body carries many low, closely set ribs divided into small, woolly areoles.
The plant's chief charm is its spination. Numerous fine, bristle-like white radial spines lie over the surface in a dense, silvery web, while a smaller number of stiffer central spines stand out from them — often coloured reddish-brown, amber or darker, so that the pale coat is stippled with warm points of contrast. The intensity of this colouring varies from plant to plant and has been selected in cultivation.
Flowers appear from the woolly crown in late spring and early summer: satiny, bright yellow, funnel-shaped and 3–4 cm across, opening over sunny days and often produced generously on a mature plant. They are followed by small, dry fruits containing fine seed.
Distribution and habitat
The species is native to southern Brazil and Uruguay, where it grows in grassland and among rocks on low hills and open slopes. In habitat the plants nestle among grasses and stones that give a little shade and shelter, rooting in well-drained, often gritty or rocky ground that dries between rains. The climate provides warm, moist summers and cooler, drier winters — a rhythm worth echoing on the windowsill or in the greenhouse.
Cultivation
Parodia scopa is an excellent beginner's cactus: hardy, floriferous and more tolerant of watering than many desert species, provided the drainage is good. Grow it in a free-draining, mostly mineral mix in a pot that drains freely, and give it bright light with a little protection from the most scorching afternoon sun, which can scorch the pale spines and body.
Water thoroughly through the warm months once the mix has dried out, then let it approach dryness again before the next drink; the plant is fairly forgiving but still resents standing wet. As autumn cools, taper off and keep it dry and cool over winter — a dry winter rest not only prevents rot but is the key to a good crop of flowers the following summer. See Watering and Repotting for general technique, and feed sparingly during active growth.
Propagation
Seed is the usual and most reliable method: sown on a warm, damp mineral surface and kept humid, the fine seed germinates readily, and seedlings grow at a steady, satisfying pace. Older plants that have produced basal offsets can also be increased vegetatively — the pups are removed, allowed to callus, and rooted much like any offset. See Propagation — seed for a full walkthrough.
Common problems
- Rot — the main risk, almost always from a soggy, slow-draining mix or winter watering; the plant softens and discolours from the base.
- Etiolation — too little light makes the body stretch and pale and dulls flowering.
- Pests — mealybugs (white fluff tucked among the spines and areoles) and red spider mites are the usual offenders; watch also for root mealybugs at repotting time. See Pests and diseases.
See also
- Parodia — the genus overview
- Soil and potting mix · Watering · Propagation — seed · Propagation — offsets · Repotting · Pests and diseases