Plate No. 23
Blue Chalk Sticks
Senecio mandraliscae
"A wash of chalky blue"
Native to
Coastal scrub of the Eastern Cape, South Africa
History
A brief account
Blue Chalk Sticks is a striking coastal succulent with powder-blue stems that seem almost painted in chalk. It was named in honour of the Sicilian botanical patron Baron Mandralisca and introduced to European cultivation in the late 19th century, where it quickly became prized for its cool colour and low, spreading habit. In its native habitat along the cliffs above the Indian Ocean, it forms soft mats that can endure wind, salt, and intense sun. Its silvery-blue tones make it especially handsome in sunny containers and rock gardens.
How to care for
Place Blue Chalk Sticks according to its light needs: Full sun. Colour deepens with stronger light. For watering, sparingly — drought-tolerant once established. For the potting medium, use lean, sandy, fast-draining mineral mix. Good drainage is essential: let surplus water escape freely and never leave the roots standing in a wet saucer.
5–30°C. Tolerates short light frost. Check the compost before watering instead of following a rigid calendar, since light, temperature, pot size and season all affect how quickly it dries. During slower growth, reduce watering and wait longer between drinks.
How to propagate
Stem cuttings root readily in dry soil. Propagation is most reliable during the plant's active growing season, when warmth and good light help new roots establish. Start with clean tools and healthy material, and keep the new plant in conditions appropriate for the parent.
Where a cutting or division creates a wound, allow the surface to dry before planting unless the method calls for immediate rooting in water or moist mix. Once roots form and fresh growth appears, gradually move the young Blue Chalk Sticks into its normal watering routine; excess moisture is especially risky while the root system is still small.
Cultivation
Quick tips for care & planting
- Light
- Full sun. Colour deepens with stronger light.
- Water
- Sparingly — drought-tolerant once established.
- Soil
- Lean, sandy, fast-draining mineral mix.
- Temperature
- 5–30°C. Tolerates short light frost.
- Propagation
- Stem cuttings root readily in dry soil.