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Corncob Cactus

Euphorbia mammillaris, Euphorbiaceae

Sources last read 14 September 2026.

Not yet rated How forgiving it is has not been judged here yet.

Also called Corn Cob Plant, Corncob Euphorbia and Indian Corn Cob.

Corncob Cactus (Euphorbia mammillaris), the whole plant.
Raffi Kojian, CC BY-SA 3.0 · Wikimedia Commons

Corncob Cactus is toxic

  • Not assessed for cats. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
  • Not assessed for dogs. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
  • Toxic to people. Toxic to people (low severity). NC State Extension

What the sources say about its care

Light
Full sun, Partial Shade
NC State Extension · read 13 September 2026
Water
Good Drainage
NC State Extension · read 13 September 2026
Humidity

No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.

Most foliage plants prefer more humidity than a heated room gives; succulents are named as an exception
Penn State Extension · read 13 September 2026
Soil
Loam (Silt), Sand; pH Acid (<6.0), Alkaline (>8.0), Neutral (6.0-8.0)
NC State Extension · read 13 September 2026
Toxic to cats
Not on the ASPCA list. That is not a finding of safety.
ASPCA · read 13 September 2026
Toxic to dogs
Not on the ASPCA list. That is not a finding of safety.
ASPCA · read 13 September 2026
Harmful to people
Toxic to people (low severity)
NC State Extension · read 13 September 2026

Routine care

Watering
Water weekly in summer and as little as once a month in winter. Let the soil dry out before watering again.
NC State Extension · read 13 September 2026
Feeding
Feed with diluted fertilizer from late spring into summer.
NC State Extension · read 13 September 2026
Propagation
In spring or summer, root stem cuttings to make new plants.
NC State Extension · read 13 September 2026
Pests and diseases
Can be troubled by mealybugs.
NC State Extension · read 13 September 2026

Move something and watch

Loading the simulator. It needs JavaScript; the care table above does not.

Close view of Corncob Cactus (Euphorbia mammillaris) foliage.
Close upSalicyna, CC BY-SA 4.0 · Wikimedia Commons

About the plant

Euphorbia mammillaris is a plant species endemic to Cape Province of South Africa. Euphorbia mammillaris, also known as African or Indian corn-cob, is a fast-growing shrublet, with thick stems that are chalky green, erect and ribbed.

From Wikipedia, CC BY-SA 4.0 · read 13 September 2026

Native range
S. Cape Prov.
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Cape Provinces, South Africa
NC State Extension · read 13 September 2026
Climate
subtropical
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Growth form
succulent subshrub
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Succulent; habit erect, spreading
NC State Extension · read 13 September 2026
Size
Height 8–24 in
NC State Extension · read 13 September 2026
Flowering
Flowers gold/yellow; blooms in spring, summer, winter
NC State Extension · read 13 September 2026

Other Euphorbia

More of the Euphorbiaceae family

Plants with similar care

Sources

What this does not cover

The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.

Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.

If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.