Euphorbiaceae
Corncob Cactus (Euphorbia mammillaris)
Euphorbia mammillaris
Easy: full sun or very bright light, a gritty, fast-draining mix, and water only when the mix is dry, almost none in winter. It is frost tender; below about 5 °C keep it indoors. Feed with diluted fertiliser from late spring to summer. Wear gloves when handling it, because the milky sap irritates skin and eyes.
Every 7 days
Direct sun
5° - °C
% - %
Categories
What is Corncob cactus?
Corncob cactus (Euphorbia mammillaris) is a easy-care plant from the Euphorbiaceae family. Corncob cactus (Euphorbia mammillaris) is a succulent in the spurge family (Euphorbiaceae), endemic to the Cape of South Africa, where it grows among thorny bush in the Little Karoo and the southern Cape. Despite the name, it is not a cactus. It forms clumps of erect, thick, chalky-green stems with...
Corncob cactus grows up to 60cm, spread of 60cm, watering every 7 days. It is suitable for indoor environments and not safe for pets.
Unlike many tropical plants, Corncob cactus tolerates watering mistakes. Best for beginners. Without precautions, ingestion can cause irritation in pets. Keep out of reach of cats and dogs. Without adequate drainage, root rot can develop within 14 days.
How to Care for Corncob cactus?
TLDR: Corncob cactus needs Direct sun, watering every 7 days, and temperatures between 5-30°C with 40-70% humidity.
How Often Should You Water Corncob cactus?
In summer water about once a week, always letting the mix dry out completely between waterings. In winter water once a month at most. Never leave water in the saucer: soggy soil rots the roots.
How Much Light Does Corncob cactus Need?
It likes full sun; indoors, give it the brightest window, ideally with a few hours of direct sun. It tolerates part shade, but a plant grown in shade must be moved into sun gradually or the stems scorch.
What Is the Best Soil for Corncob cactus?
A cactus and succulent mix with plenty of mineral grit (coarse sand, gravel, pumice or lava rock) and little organic matter. Fast drainage is what matters; it is not fussy about pH.
What Pot Should You Use for Corncob cactus?
A small terracotta pot with a drainage hole; it likes snug pots. Terracotta helps the mix dry out faster.
Care Schedule
Fertilize
Every 30 days
What Is Corncob cactus and Where Does It Come From?
Corncob cactus (Euphorbia mammillaris) is a succulent in the spurge family (Euphorbiaceae), endemic to the Cape of South Africa, where it grows among thorny bush in the Little Karoo and the southern Cape. Despite the name, it is not a cactus. It forms clumps of erect, thick, chalky-green stems with 7 to 17 ribs of hexagonal tubercles lined up like kernels on an ear of corn. The whitish "spines", up to 1 cm, are actually old flower stalks. It reaches 20 to 60 cm and branches from the base. From late winter to early summer it bears tiny yellow, orange or pink flowers at the stem tips. Like every euphorbia, it has an irritant white latex.
How to Propagate Corncob cactus?
Stem cuttings
Take cuttings from late spring to summer, in the growing season. Do not water before the cut has callused, or the base will rot.
- 1 Wearing gloves, cut a side shoot at its base with a clean knife
- 2 Rinse the cut with water to stop the latex
- 3 Let the cutting dry in shade for 1 to 2 weeks until callused
- 4 Plant it in dry mineral mix
- 5 Wait a week before a first light watering
Materials needed:
How Big Does Corncob cactus Grow?
TLDR: Corncob cactus can reach up to 60cm tall with Medium growth rate.
Max height
60cm
Spread
60cm
Growth rate
Medium
Foliage
Evergreen
Warning: Toxic Plant
This plant can be toxic if ingested. Keep out of reach of:
Plant Uses
Ornamental
Great for decoration
Is your plant showing symptoms?
Click on the symptom to discover possible causes:
What Diseases Commonly Affect Corncob cactus?
TLDR: Corncob cactus is susceptible to 7 known diseases. Monitor regularly for early detection.
Mealybugs
Mealybugs are small, soft-bodied insects covered with a white, waxy, cottony material. They are common pests of houseplants and outdoor plants in mild climates. These sap-sucking insects feed on plant tissue, causing damage, stunted growth, and can lead to plant death if left untreated. They produce sticky honeydew which attracts sooty mold.
Scale Insects
Scale insects are small sap-sucking pests that appear as brown, shell-like bumps on plant stems and leaves. There are over 25 species, divided into armored (hard) and unarmored (soft) scales. They feed by piercing plant tissue and extracting sap, which weakens the plant and can lead to yellowing, stunted growth, and even death if left untreated. They also excrete honeydew, which attracts ants and promotes sooty mold growth.
Spider Mites
Spider mites are tiny arachnids (less than 1/20 inch long) related to spiders and ticks that feed on plant sap. They thrive in hot, dry conditions and can cause significant damage to ornamental and vegetable plants. During severe infestations, crop losses can reach 14% or higher as these pests disrupt vital plant processes including photosynthesis, carbon dioxide absorption, and transpiration.
Root Rot
Root rot is a serious fungal disease that affects the root system of plants, causing them to decay and die. It is primarily caused by overwatering, poor drainage, or soil-borne fungi such as Pythium, Phytophthora, Rhizoctonia, and Fusarium. The disease thrives in waterlogged conditions where roots are deprived of oxygen, making them susceptible to fungal infection.
Fun Facts
The name mammillaris refers to its resemblance to Mammillaria cacti, though it is not a cactus
Its spines are dried, hardened flower stalks
Each plant is either male or female
Frequently asked questions
Is corncob cactus a real cactus?
Is corncob cactus toxic?
How often should I water corncob cactus?
What pests attack corncob cactus?
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