Despite its common name, the coral cactus (Euphorbia lactea ‘Cristata’) isn’t a cactus at all. It is actually two different kinds of succulents that have been grafted together to create this sculptural, other-worldly-looking plant. The top ruffled portion of the plant is the crest of a Euphorbia lactea, while the green ‘stem’ (or rootstock) is a Euphorbia neriifolia. Once grafted together, these two Euphorbias make up the coral cactus. Depending on the variety of Euphorbia lactea used to create the coral cactus, the top crest of the plant can vary from green to blue-grey, to whitish-green in color.
The coral cactus is a popular houseplant, not only because of its unique appearance but also because it’s low-maintenance and easy to care for. Before bringing one of these succulents into your home, be aware that like all plants in the Euphorbia genus, the latex sap of the coral cactus is considered toxic to both pets and humans.
What is Grafting?
Grafting is a propagation technique that joins two plants into one. This is accomplished by connecting the bottom portion of one plant (rootstock) to the top portion of another (scion) and allowing the tissues to grow together, where they will continue their growth as one plant.
|Botanical Name||Euphorbia lactea ‘Cristata’, Euphorbia lactea x neriifolia|
|Common Name||Coral cactus, crested Euphorbia, crested elkhorn, crested candelabra plant, candelabra plant|
|Mature Size||1-2 ft. tall (indoors)|
|Sun Exposure||Full, partial|
|Soil Type||Sandy, well-drained|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Spring, summer|
|Flower Color||Pink, purple|
|Hardiness Zones||10-11 USA|
|Toxicity||Toxic to pets, toxic to humans|
Coral Cactus Care
Caring for a coral cactus is relatively straightforward, although it does differ slightly from most desert cacti and succulents. This Euphorbia mix is more tolerant of shady conditions than most Euphorbias, and also requires more frequent watering. Additionally, since this succulent is made by manually grafting two Euphorbia plants together, it cannot be propagated in the traditional sense, such as through stem cuttings, division, or by seed. In order to create new coral cactus plants, you would need to follow the grafting process.
This succulent does best with plenty of light. When growing the coral cactus indoors, choose a location that gets several hours of direct light to encourage optimal growth. If you choose to grow your coral cactus outdoors where the light is more intense, a location that is partially shaded is best. Make sure that you rotate your plant regularly (if you are growing it in containers) to prevent lopsided growth.
To prevent overwatering and waterlogged soil choose a light, well-draining soil mix that is amended with plenty of perlite and sand. Cactus and succulent soil is designed specifically for these types of plants and provides lots of drainage, but you can also make your own at home if you wish. Simply mix together equal parts potting soil, perlite, and sand.
The coral cactus is not as drought-tolerant as some of its close relatives in the Euphorbia family. It should not be allowed to dry out and does best when watered once the top 2 to 4 inches of soil is dry. However, don’t worry if you forget the occasional watering as it can bounce back from minor periods of drought.
Temperature and Humidity
This Euphorbia enjoys warm, dry conditions which makes it well-suited to indoor growing. That being said, it can also be grown outdoors year-round in USDA zones 10 to 11. Alternatively, for growers that live in colder regions, this succulent can be grown outdoors during the spring and summer and then moved back indoors during the chilly fall and winter months. Avoid exposing the coral cactus to temperatures below 60 degrees Fahrenheit (15 degrees Celsius) to prevent putting the plant into shock.
The coral cactus is not considered a high-feeder but can benefit from some light fertilization during the spring and summer. Apply a fertilizer designed for cacti and succulents once a month until the fall and then stop applications until the following spring.
Potting and Repotting Coral Cactus
Due to the fact that these plants are grafted, they rarely (if ever) outgrow their pots. However, it is still a good idea to repot them every few years to provide the plant with fresh soil and upsize the pot if needed. Wait until the spring or summer months when the plant is actively growing to repot, as this will prevent the plant from going into shock.
Common Pests and Plant Diseases
Watch out for common houseplant pests like scale, mealybugs, spider mites, and aphids which can all take up residence on this Euphorbia. If you notice pests on your plant, isolate it from your other plants immediately and remove any pests you can see with an alcohol-soaked cotton swab. You can also use neem oil or insecticides to help treat more serious infestations. In addition to these common pests, coral cacti are also susceptible to root rot which usually results from overwatered conditions.
Common Problems With Coral Cactus
Besides some common houseplant pests and diseases, caring for the coral cactus is relatively simple and problem-free. However, there are a couple common problems to watch out for, including yellowing, and brown spots developing on the rootstock or top crest of the plant.
If your coral cactus is turning yellow it is likely that the plant is suffering from overwatering. While these succulents enjoy more frequent watering than some other types of Euphorbias, they should still be allowed to dry slightly between waterings and should never be kept in consistently moist soil conditions. If you suspect overwatering is the culprit, repot your coral cactus with fresh, dry soil immediately.
Brown spots can show up on your plant in two different ways—as brown mushy spots, or as hardened ‘crispy-looking’ spots. Out of the two, brown mushy spots are by far the more concerning result and are usually an indication of some kind of rot or fungal infection. First things first: it’s a good idea to check the roots of your plant in order to rule out root rot. If root rot is not the culprit then it’s likely that your coral cactus is suffering from a fungal infection, at which point cutting out the affected area is the best course of action.
Usually, hard brown spots are less concerning and are sometimes just a ‘scar’ on the plant’s skin from a previous wound that healed over. They can also be a result of sunburn which might occur if your plant is suddenly moved from a shady location to an extremely bright location.
How big does a coral cactus grow?
These grafted plants rarely grow taller than 1 to 2 feet tall. While the grafting process successfully combines two separate plants that will live on as one, neither plant will continue to grow to its full potential once grafted together. This means that the coral cactus is often more of a decorative plant than a plant that you can watch grow over time.
Why is my coral cactus turning pink?
Environmental stress can cause the top portion of a coral cactus to start turning pink. While it sounds bad, stress isn’t necessarily a bad thing for a plant although it is usually an indication that something in the plant’s growing environment has changed. For example, if you recently moved your coral cactus from a partially shaded location to a bright location you may notice its colors change. As long as the plant’s overall conditions are still okay your plant is likely going to be fine. However, if you are worried you can try to determine which change is causing the stress and reverse it.
Why is my coral cactus growing branches and leaves?
If you have had your coral cactus for a long time, it is not uncommon for it to start growing new branches and leaves from the bottom stem of the plant. This is a natural progression of the growth of the Euphorbia neriifolia which makes up the rootstock of the coral cactus. While it may change the overall look of your coral cactus, it is a sign that the plant is happy and growing well. If you don’t like the look of it, you can always remove the branches using a sharp pair of pruning shears or scissors.