Caring for Coral Cactus

What do you call a cactus that isn’t a cactus? Sometimes known as the candelabra plant, the crested euphorbia, or the crested elkhorn, the coral cactus is actually a melding of two succulent varieties. The grafted plant resembles an unusual coral, and depending on the variety, the edges of its crinkled leaves can be white, yellow, green, red or purple.

It can – very rarely – produce pink or purple flowers. Only older plants will flower, and many may never produce a bloom.

Though it may look like a stunning cactus, if treated as such, your crested cactus will be very unhappy. This Frankenstein’s monster of the plant world actually prefers a humid environment.

What is a coral cactus

The coral cactus is comprised of two types of succulent from the Euphorbia genus – a surprisingly large family of over 2000 plant species.

The base is usually a Euphorbia neriifolia, a plant that resembles a cactus with wide, oval leaves. It’s chosen for its tendency to grow straight and tall. Euphorbia lactea – often the ‘Cristata’ variety – with its large, rippled, fan-like leaves is then grafted to the top.

A word of caution

Like many euphorbia species, both the base and crest of the coral cactus may have sharp spines that can cause irritation. Use caution when handling the plant to avoid injury.

The sap, or latex, of the coral cactus is toxic and can be very dangerous. The thick white sap may cause skin conditions if it is touched – it’s best to wear gloves and avoid the risk of dermatitis or other rashes or skin reactions. If ingested, the latex will cause nausea or vomiting. And if it gets in the eyes, it can irritate them or even cause temporary blindness.

It’s safest to only touch the plant when absolutely necessary, and you should wear gloves at all times for maximum protection. If you must pick up the plant, either use long tongs or hold the pot to avoid contact with the latex.

Propagating coral cactus

While most euphorbias are propagated by cuttings rather than seed, a coral cactus can only be creating by grafting. The process can be slightly complex. As mentioned above, you should wear gloves while grafting your plant.

You must begin by choosing a healthy young euphorbia neriifolia and eurphorbia lacteal – the younger plants generally take to grafting better than older, established plants. Try to choose plants that you feel would look right together.

Next, you’ll cut a V-shape into the base plant, removing its upper portion but leaving enough of the stem sides to support the crest. Then, cut the stem of the lactea in an arrowhead shape so that it fits snugly into the neriifolia stem. Any gaps between the two plants will allow the latex to leak out and might result in the formation of fungal rots.

Once the two plants are tightly fitted together, use grafting wax to cover the join, ensuring they remain sealed and clean. Use twine to reinforce the grafted joint. It will take at least 2-3 weeks for the plants to fuse together, but don’t be concerned if it takes longer.

After 3 weeks, it’s time to remove the twine and wax to inspect the joint. If it doesn’t appear to have fully fused, apply fresh wax and retie the twine in place. After another 3 weeks, check the plant again.

Caring for coral cactus

This mishmash of euphorbia plants requires particular care. In zones 10-11, it can remain outdoors year-round, but should spend the cooler months indoors in any other region. It can be grown indoors as well.

Soil and fertilizer

Coral cactus prefers a cactus potting soil or any other gritty soil that provides good drainage. You can mix a bit of organic matter into the planting hole for added nutrition, though it’s not strictly necessary. Euphorbia can tolerate changes to the soil pH; they will do well in either slightly alkaline or slightly acidic soil.

Storebought grafted plants may have been mulched with gravel which is glued together to help support the plant during transit. The layer of gravel will not harm the plant, but may make it difficult to determine if the soil is dry and the plant needs watering.

During the spring and summer, the cactus should be fertilized regularly using a 10-10-10 liquid fertilizer at ¼ strength every couple of weeks at most. In especially rich soils, even less fertilizer is required. The plant doesn’t require any extra nutrition in the fall or winter.

Light and temperature

New plants should be started in partial shade conditions and can be moved gradually to full sun. In hot regions, the plant should be partially shaded during the heat of the day to avoid sun damage.

If grown indoors, the plant should be placed in a window with 3-5 hours of bright sunlight daily. As the crest will grow toward the sun, you should turn the pot regularly to prevent the cactus from growing lopsided. 

Like most succulents, the coral cactus will only thrive in warm temperatures of at least 10°C and preferably above 15 °C – if your outdoor temperatures dip below this, bring your plant indoors. Frost or freezing will damage the fragile tissues of the coral cactus and most likely kill it.

Water and humidity

Contrary to most succulents and cacti, the coral cactus doesn’t tolerate drought conditions – though it does prefer drier soil. Soggy soil may cause problems like root rot.

A good rule of thumb is to water when the top 5-10 cm of the soil seems dry. Do not water the plant directly, but instead water the soil until it runs out of the pot base. A droopy or wilted coral cactus is probably under-watered.

The coral cactus will need more frequent watering during its active growth period in the spring and summer months. You can reduce the frequency of water during the fall and winter.

Coral cactus also enjoys humid environments such as greenhouses – provided there is good airflow. If growing coral cactus indoors, watch for signs of powdery mildew.

Coral cactus problems

These plants are rather hardy and not susceptible to many issues.

Growing problems

The grafted coral cactus can rarely be subject to reverting – the rootstock may try to develop as usual, resulting in a secondary stem of neriifolia next to the lactea crown. If this happens, you can either leave it – creating an even more unusual plant, or remove it carefully near the crest and allow the latex to scab over the cut portion.

Pests

Though the latex is a good deterrent to most pest, mealybugs and other scale insects may still appear on coral cactus. Use a cotton swab dipped in slightly diluted rubbing alcohol to remove them.

Spider mites may also affect coral cactus. Because insecticidal soaps can harm the plant, use a firm spray of water to remove the spider mites and their eggs, then allow the plant to dry thoroughly. Heavily diluted neem oil can also be effective for removing spider mites.

Diseases

In humid environments with limited airflow, powdery mildew may develop – this disease is best prevented as many of its treatments will harm the coral cactus’s leaves. If mildew appears, the plant surface can be treated with a solution of baking soda (15 mL) in water (4L).

If the soil is too wet, the plant may develop root rot – use a cactus potting mix and water only when necessary to avoid root rot. Once the coral cactus begins to show damage, it’s usually too late to save it from root rot.

Fungal rots can also develop during the grafting process, or on the leaves of a plant that has been exposed to cold. This usually presents as browned and mushy parts on the leaves which may be pruned away.

Growing a coral cactus is an experience unlike any other – both challenging and beautiful!

Get your own Coral Cactus today!

Costa Farms Coral Cactus Live Indoor Tabletop Plant in Flared Pot, Turbulence Gray

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Features

  • Do not recommend shipping to states currently experiencing extreme cold weather/temperatures.
  • The Delray Plants' coral cactus is an artistic take on a Desert classic
  • The coral cactus will invite conversation over its unique, splayed foliage & interesting ripples
  • Indoor foliage plants are one of the most sensible decisions one can make for home improvements
  • We're unable to ship this item to: AK,AZ,CA,GU,HI

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