Indian Corn Cob Plant Info: How to Grow and Care for Euphorbia mammillaris
The Indian corn cob (Euphorbia mammillaris) is a columnar cactus-like plant that grows into dense clusters. The chalky green stems are ribbed and occasionally covered with blunt spikes that resemble toothpicks. From late winter to early summer, this succulent produces yellow flowers.
Native to South Africa, the Indian corn cob cactus is a drought-tolerant plant that requires less pampering. Its hardiness zone is 9-11, meaning it cannot survive a hard frost. So, you must bring it indoors during the cold winter months to prevent it from being damaged.
Caring for this plant is relatively easy. Its watering needs are low and it prefers full sun and well-draining soil. Since it grows tall, protecting it from strong winds is important. I find corncob cactus a perfect addition to beds, borders, and Mediterranean Gardens.
Caution: This plant contains white sap that can irritate eyes, mouth, nose, and open wounds. So wear gloves when handling it and wash your hands with soap and water if contact is made with the sap.
| Common names | Indian corn cob plant, Corncob cactus |
| Botanical name | Euphorbia mammillaris, previously Euphorbia fimbriata |
| Plant type | Cactus-like succulent |
| Mature size | 1ft-2ft tall |
| Sun exposure | Full sun |
| Bloom season | Late winter to early summer |
| Flower color | Golden-yellow |
| Soil type | Well-draining soil |
| Hardiness zone | 9-11 |
| Toxicity | Can be toxic to humans and pets when ingested. |
Care information for corncob cactus
As I said, the Indian corn-cob cactus has low maintenance needs. Here is what it takes to grow and care for this succulent.
How to water
The Indian corn cob plant is a drought-tolerant plant. As such, it needs less watering. Overwatering can cause root rot and other fungal problems. Water once a week during the growing season in spring and summer and only once per month during the winter months.
The best time to water this plant is when the soil is completely dry. So, before watering, check the soil moisture level. You may insert your finger in the soil or use a moisture meter. Water it only when the soil feels dry to the touch.
Light requirement
This plant thrives in full sun to partial shade. So, when growing it indoors, be sure to place it where it can receive at least 8 hours of direct sunlight. An east or south-facing window can be a perfect spot. In low light conditions, this plant may grow spindly (thin and long).
In areas without sufficient sunlight, you may use artificial grow lights to supplement the natural light, particularly during the winter months when daylight hours are shorter.
While this plant needs maximum sun exposure, excessive intense sunlight can scorch the stems. Therefore, protection during the hottest part of the day is crucial. You can use a sheer curtain to diffuse the light or use other plants to block the sunlight.
Soil and fertilizer
The corncob cactus prefers well-draining soil. So, when growing use cactus or succulent potting mix. You may also combine regular potting soil with sand, pumice, or perlite in equal parts. Soils that drain poorly can cause root rot and other fungal issues.
While this succulent isn’t a heavy feeder, it can benefit from occasional fertilization during the growing season. So, apply a well-balanced fertilizer diluted to half strength once or twice every four to six weeks in spring and summer to boost growth. Stop fertilizing during the winter months.
Temperature and humidity
The Indian corn cob plants do well in warm temperatures ideally between 60°F to 80°F. If you live in a region with cold winters, consider bringing this plant indoors. Temperatures below 50°F can damage or kill it. Additionally, It prefers dry conditions and low humidity levels.
Ideally, humidity should be kept around 30-40%, which is typical of indoor environments. In places with higher humidity levels, ensure there is proper air circulation around the plant to avoid fungal issues.
Potting and repotting
Repotting corncob cactus is necessary when it has outgrown its current pot. This is typically after every 3 to 5 years. When potting or repotting, use cactus or succulent potting mix and a pot with drainage holes. The best time to repot is in spring or early summer.
Pruning requirements
Pruning the Indian corn cob succulent can be necessary when removing dead or damaged parts. You may also do it to maintain the plant’s size and shape. Use clean sharp cutting tools to avoid spreading pathogens. Prune in spring or summer during active growth.
How to propagate the Indian corn cob cactus
The Indian corn cob cactus can be propagated through stem cuttings or division. Before you handle the plant, wear protective gloves to avoid any contact with its sap. As said, it can irritate the skin, eyes, nose, and mouth.
Stem cuttings method
- Choose a healthy stem from the parent plant. It should not be damaged by either a disease or pests.
- Using a clean, sharp knife or pruning shears, cut the stem, preferably at a joint.
- Place the cutting in a shaded area for 2 or 3 days to dry and callous over. This prevents the cut end from rotting.
- Plant your cutting into well-draining cactus or succulent soil. Also, the pot should have drainage holes.
- Mist the soil and place the pot in a bright indirect light. The next watering should be when the soil is completely dry.
- The cutting will take a few weeks to grow roots and establish.
To propagate by division, inspect if the mother plant has offshoots or pups. Carefully separate them ensuring each has its own roots. Plant the divisions in new pots with well-draining soil. Water lightly and place them in a spot that receives bright indirect light.
Common problems and diseases
The Indian corn cob plant is generally hardy but it can experience a few challenges.
Overwatering can cause root rot. Excess moisture in the soil stops air from reaching the roots. As a result, they drown and die. The condition also promotes fungi that cause root rot.
If the cactus has root rot, it may shrivel or wilt. Since this can also mean that your plant hasn’t received enough water, inspect the roots for any damage. Dark mushy roots are a sign of root root rot. To save the plant, you’ll need to remove the affected roots and repot it in fresh succulent soil.
Pests such as mealybugs, aphids, and spider mites can also infest the plant. This can cause serious damage to the plant because they suck sap from the stems and leaves. If discovered, treat pests with neem oil or insecticidal soap. So, inspecting your plants regularly is crucial.
Final thought
The Indian corn cob plant is a unique addition to any garden. It generally has low maintenance needs. Grow it in well-draining soil, water only when the soil is completely dry, and provide plenty of bright indirect sunlight.
My name is Diane M Lewik, and I am the founder of this website. I am a degree holder in plant biology from the University of California – Berkeley. Over the years, I have cultivated a vast collection of succulents and I have learned a great deal about how to grow and care for these unique plants. Feel free to ask any questions in the comment section below.
