Groundcover
Blue Chalksticks
Curio repens · Asteraceae
Also called: Blue Chalksticks, Blue Chalk Sticks, Blue Fingers, Creeping Blue Chalksticks
Blue Chalksticks (Curio repens) is a very low-water groundcover well suited to Tucson and the low desert. It's a moderate-growing groundcover.
Blue Chalksticks at a glance
- Water use
- Very Low (established)
- Sun
- Full sun to part sun develops the best powdery blue color; in Tucson it takes full sun in cooler months but appreciates light afternoon shade in peak summer to avoid tip scorch. Too much shade makes it stretch and lose color.
- Mature size
- Spreading mat about 8-12 in tall and 2-3+ ft wide
- Growth rate
- Moderate
- Bloom
- Off-white to pale cream (insignificant), Small whitish flower clusters appear mainly in summer; grown primarily for its blue foliage, and flowers are often sheared off.
- Cold hardiness
- Hardy to roughly the mid-to-high 20s F (about USDA 9b-10), so it is one of the more cold-tolerant tender succulents in Tucson; foliage may bronze or burn in a hard freeze but usually recovers. Light frost protection helps in cold pockets.
- Soil
- Well-drained gritty or sandy soil; performs well in decomposed-granite beds and raised plantings. Avoid soggy clay.
- Native range
- Western Cape, South Africa
- Best used as
- Low-water groundcover, Rock and cactus gardens, Container spiller, Edging and erosion control on slopes, Color contrast against greens and golds
- Wildlife
- Minor pollinator value; valued mainly as a xeriscape foliage groundcover.
- Toxicity
- Considered toxic if ingested (as a Senecio/Curio relative it can contain irritant compounds); keep pets and children from eating it, though it is mainly a contact/ingestion-irritant concern.
How to grow Blue Chalksticks in Tucson & the low desert
Watering
Very drought-tolerant once established; water deeply but infrequently (every 1-2 weeks in summer heat, monthly or less in winter) and let soil dry fully. Excess water and poor drainage are the main killers.
Fertilizer & nutrients
Low needs; an annual light topdress of compost or one dilute feeding in spring is plenty. Over-fertilizing causes weak, floppy growth.
Pruning & care
Trim or pinch back to keep the mat dense and tidy; cut stems re-root easily where they touch soil, making it easy to spread or fill gaps.
Notes
Accepted name Curio repens (syn. Senecio serpens); the very similar, taller, larger-leaved 'blue chalk sticks' in trade is Curio talinoides var. mandraliscae (syn. Senecio mandraliscae). An excellent low-desert xeriscape groundcover-pair with agave, golden barrel, and aloes; mass-plant in well-drained sun for a striking blue carpet.
Sources: AMWUA Landscape Plants for the Arizona Desert; University of Arizona Cooperative Extension / Pima County Master Gardeners; World of Succulents (worldofsucculents.com); Wikipedia: Curio repens