Houseplant · Asteraceae
Senecio
Senecio
Upright, finger-like leaves in chalky blue-green, dusted with a soft powdery bloom, give this succulent its cool, frosted look.
Full sun
Every 10–21 days
50–77°F · 10–25°C
USDA 9–11
Overview
Senecio covers a range of succulents defined by their cool blue-green color and a fine, chalky powder over the leaves. On the chalkstick kinds, the leaves stand upright and finger-shaped, each one plump and firm to the touch beneath its frosted coating. In summer small flowers open in white to cream, though it is the foliage, not the bloom, that draws the eye. Many now carry the genus name Curio while still selling as Senecio.
Those thick leaves feel dense and full of stored water, and that reserve shows in how they change. Left dry too long, the leaves wrinkle and soften, then fill out plump and taut again after a drink. Across the surface, the powdery bloom gives the blue-green skin a matte, chalk-dusted finish.
Behind the cool looks sits a real hazard. The tissue carries pyrrolizidine alkaloids that damage the liver, and a cut stem weeps a sap that can sting bare skin, so this is a plant to look at closely and keep away from pets, livestock, and children.
Care
The short version: set it in the strongest light on hand, use a gritty mix that pours water straight through, and wait until the soil is bone dry before the next watering.
Light
It wants the strongest light on offer, full sun outdoors or the brightest window indoors. Starved of it, the stems draw out long and thin and tilt toward the glass, so a grow light fills in where a bright spot is missing.
Water
Wait for the soil to go fully dry and the leaves to start puckering before you water, which usually means every 10 to 21 days. The fleshy tissue rots far sooner than it shrivels, so cut watering right back through winter dormancy.
Soil
Grow it in a gritty, fast-draining cactus or succulent mix so water slips past the roots without pooling. A pH of 6.0 to 7.0 suits it, and a drainage hole in the pot counts for more than the exact mix.
Temperature
It holds up between 50°F to 77°F (10°C to 25°C). Frost damages the soft, water-filled tissue, so move it indoors or under cover before the cold arrives.
Humidity
Dry air suits this succulent, and there is no humidity target to meet. Ordinary indoor air keeps it firm and healthy, while damp, stagnant air softens the tissue and invites rot.
Feeding
A light feed through spring and summer, while new leaves are forming, is all it needs. A diluted balanced or low-nitrogen cactus fertilizer once a season is enough, with none through winter.
Pruning
There is little to cut. In spring, pinch back the leggy or overgrown stems, take off any dead or shriveled leaves, and press the firm tip cuttings into soil to grow more plants.
Repotting
Repot it every 2 to 3 years, or sooner once the roots crowd the pot. Roots poking from the drainage holes, soil that dries in no time, and growth that has stalled all mark the moment to move it up.
Size & spacing
A mature plant reaches 10 to 18 inches (25 to 45 cm) tall and spreads 18 to 35 inches (45 to 90 cm) across. Left to spread, the upright leaves form a low blue-green carpet, or the stems hang over a pot edge in trailing ropes.
Troubleshooting
Almost every trouble here shows up first in the leaves and stems, and nearly all of it comes down to water or light. Too much water rots the plant from the inside, the one failure that kills, while light problems mostly just mar its color and shape. Match the look of your plant to the cases below and act early.
Soft, mushy stems blackening at the base
When the stems turn soft, water-soaked, and black near the soil, the plant has root and stem rot, the usual end for a chalkstick succulent and the result of too much water or a mix that holds it. Stop watering, cut back until only firm, healthy tissue remains, and let the good cuttings callous before they go into dry gritty mix. Hold the next watering until the soil is bone dry.
Fix:
- Stop watering immediately
- Cut away rotted tissue and let healthy cuttings callous
- Repot sound growth into dry gritty cactus mix
- Resume watering only once soil dries completely
Stretched stems with pale, widely spaced leaves
Long bare gaps opening between the leaves, with the stems bending hard toward the window, are the marks of etiolation, growth reaching for light it lacks. Move it into brighter light, raising the exposure over a week or two so the tissue does not scorch. The drawn-out tips root readily once pinched off and set in soil.
Fix:
- Move to a brighter spot with several hours of direct or bright light
- Acclimate gradually to avoid sunburn
- Pinch back and propagate leggy tips
Wrinkled, softened leaves on bone-dry soil
Leaves that have gone wrinkled and soft over long-dry soil have spent their stored water. A deep watering until it runs from the pot refills them, and the usual dry-down cycle picks back up. The wrinkles smooth out and the leaves turn firm again within a day or two.
Fix:
- Water thoroughly until it drains from the pot
- Resume the regular dry-down watering cycle
Bleached, brown scorch on sun-struck leaves
Bleached, brown patches burned into the leaf faces that catch the most sun are sunburn, usually after a sudden move outdoors or a heat spike. Move the plant to bright but lightly shaded light and cut away the worst-marked leaves. Raise its sun exposure by degrees next time to keep the scorch from returning.
Fix:
- Move to a bright but slightly shaded spot
- Remove badly damaged leaves
Toxicity
For all its frosted good looks, this plant is one to keep out of reach. Every part holds pyrrolizidine alkaloids that do slow, lasting harm to the liver, and a cut releases a sap that can irritate skin and eyes. It is toxic to pets, horses, and livestock and unfit for people to eat, so handle it carefully and wash your hands after taking cuttings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
A cat that bites into the leaves or stems soon vomits and drools, with diarrhea and a flat, tired look setting in after. The raw sap can sting its mouth, and the alkaloids work slow, building liver damage the longer the plant is nibbled.
Dogs Toxic
A dog that chews the plant drools, brings up its food, and turns off its meals, often with loose stools and sinking energy. The steeper danger is repeat nibbling, since the liver toxins gather with every mouthful.
Horses Toxic
Horses are hit hardest of all. The pyrrolizidine alkaloids grind out slow, permanent liver damage that can stay unseen until weight loss, dullness, and strange behavior show up weeks or months later.
Rabbits Toxic
Keep it clear of any rabbit. The same liver-damaging alkaloids act on them, and the irritant sap makes the leaves an unsafe thing to nibble.
Livestock Toxic
Cattle, goats, and sheep can take in enough alkaloid over time to fall into serious liver disease. Grazing animals face the sharpest risk where the plants spread out into open ground.
Birds Toxic
Treat it as off-limits to birds. The pyrrolizidine alkaloids bring them the same liver risk, so no bird should pick at the leaves or sap.
People Caution
No part of the plant is fit to eat. Swallowing it upsets the stomach, the alkaloids wear on the liver over time, and the sap can irritate skin and eyes, so wash your hands after handling cuttings.
Sap may irritate skin and eyes; wash hands after pruning or taking cuttings.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
A few chalkstick succulents supply most of what sells under the Senecio and Curio names, and they differ in the shape, size, and blue of their leaves. These are the ones seen most often.
Senecio (Curio) repens / mandraliscae - blue chalksticks
The classic chalkstick, forming a low mat of upright, finger-like leaves in blue-green.
Senecio (Curio) ficoides - blue chalk fingers
A larger, more upright shrubby form set apart by its broad, flattened blue leaves.
Senecio serpens - dwarf blue chalksticks
A compact, low grower with short, powder-blue cylindrical leaves that fit a small pot.
Senecio (Curio) talinoides var. mandraliscae
A vigorous, chalk-blue cultivar widely sold as a spreading groundcover succulent.
How to propagate
Senecio takes to propagation with ease, and one short length of stem, cut and rooted, becomes a whole new plant.
Stem cuttingsEasy
Spring to summer during active growth · 2 to 4 weeks
Spring and summer, while new growth is coming on, is the time for cuttings. Cut a firm stem or tip, let the raw end dry to a callus over a few days, then set it in dry gritty mix and water lightly. Fresh roots form and the cutting settles in over 2 to 4 weeks.
Myths
Every chalk-stick succulent is still a Senecio.
The naming has changed. Kew's Plants of the World Online now accepts the separate genus Curio for many succulent senecios, the chalkstick forms included. They keep selling as Senecio, so the two names sit on the very same plants.
A tough, low-water succulent must be safe around pets.
Hardiness says nothing about what the plant contains. The ASPCA lists succulent Senecio and Curio as toxic to cats and dogs, causing vomiting and lethargy, so keep them out of a pet's reach.