How to Grow, Plant, and Care For Coral Cactus

There are many plants to choose from in the weird and wonderful world of succulents. But one of the strangest has to be the coral cactus.

You’ve probably seen these in your local nursery and wondered how a plant like that could exist. The tops emerge from thick stems in a fan shape, sporting interesting spines and captivating colors that you can’t ignore.

There is a reason for this unique look and the care requirements that go along with it. Read on to learn more about why you should grow these fascinating succulents.

About Coral Cactus

You would be forgiven for assuming the coral cactus is some kind of alien rather than a plant. The only clue to the latter is that you’ll find them among other succulents in your local nursery. With weird forms, interesting spines, and unique colors, there really is nothing like the coral cactus.

This unique look is not attributed to one plant species alone but two! That’s because the coral cactus we all recognize is a combination of two Euphorbia species – Euphorbia neriifolia on the bottom and Euphorbia lactea var. Cristata is on the top.

Euphorbia lactea has interesting spines. This plant is grafted onto the more structural Euphorbia neriifolia, creating a tree-like shape made up of two completely different plants.

The name coral cactus comes from the resemblance to sea coral. Due to the overall shape, it is also labeled as the candelabra plant or crested euphorbia. The name Coral Cactus is a bit of a misnomer because this plant is not classified as a cactus at all. It is technically a succulent, related to other plants in the expansive Euphorbiaceae family, like poinsettias.

This succulent is not the only plant made from a grafting process. Moon cactus (Gymnocalycium mihanovichii) is also grafted onto another rootstock because they lack the chlorophyll needed to survive independently. However, moon cactuses are only unique in color; the coral cactus is unique in both shape and hue.

Native Area

Species in the Euphorbia genus are largely native to Africa, but the two species that make up the coral cactus actually come from Asia, particularly the Indian subcontinent.

There are many cultivars of this species grown for ornamental purposes. In this case, ‘Cristata’ is the focus, but there are other interesting cultivars to choose from. My personal favorite is ‘White Ghost,’ a succulent I became intrigued by at first glance. After several years in my home, it is still growing strong.

Unlike desert cacti which grow in intense sun, these Euphorbia species are much more tolerant of lower lighting conditions. Their low sunlight requirements and love of mild temperatures have made them popular houseplants around the world. However, your plant can perform even better outdoors if you live in the right climate.

Characteristics

The coral cactus is instantly recognizable for its fan shape, sitting on top of the strong Euphorbia neriifolia base. This crested stem structure comes in many colors, from classic green to ghostly white, purple, and even red or pink. They also have sharp spines (hinting at the cactus misnomer) that are best to avoid when handling the plant.

Along with these spines, the sap or latex of the plant is also best avoided. This substance can irritate the skin and has even harsher effects when in contact with your eyes or ingested. Wearing gloves can prevent potential problems, especially for those with sensitive skin. Plus, it protects you from touching the pointed spines.

In perfect conditions, they can flower, but it is quite rare. If you’re growing indoors, you likely won’t ever see them flower, but you can still enjoy their unique look year-round.

How to Grow

Coral cactus care is not difficult but is different from other houseplants you may already have in your collection. If you’re growing outdoors, there are important environmental conditions to be aware of to avoid permanent damage to the stems and possible early death.

Light

Coral cactuses kept as houseplants have very different lighting from the typical houseplants you likely have in your home. As succulents are found in warm and bright native habitats, they need a healthy amount of direct sun to look their best and avoid growth issues.

Slowly introduce your succulent to new lighting conditions over a week or two to avoid any damage. For example, if they came from a nursery where they were kept in full sun, give them plenty of direct light indoors until they can adjust to the lower light levels. If you find the plant in the indoor garden section in indirect light, don’t thrust it into full sun, or the plant will likely burn.

Water

As a succulent plant, coral cactus stores water in the stems for later use, allowing it to survive for short periods in dry soil. However, despite the name, this plant is not as tough as desert cacti. They cannot tolerate dry soil for long periods, as this will cause the stems to wrinkle and shrivel. Lack of water also leads to stress which can impact growth down the line.

On the other hand, overwatering is a major risk for these succulent plants. Watering too often will cause the roots and base of the plant to rot, eventually killing the entire plant. Root rot is difficult to fix once it has taken over, so prevention is key.

Aim to water when the soil is just about to dry out. It shouldn’t be completely dry for more than a few days, but if you forget to water it for a day or two, you likely won’t do any permanent damage. Test the soil with your finger or lift up the pot to determine the moisture levels before watering again.

Environment plays a big role in how often the plant will need water. The soil will dry out more quickly in the direct sun than in bright indirect light. It’s best to test the soil every couple of days until you know the necessary watering frequency.

The amount of water required also changes with the seasons. You’ll need to water more often when the weather is warm in spring and summer. In fall and winter, slowed watering reduces your chances of rot.

Soil

Succulents need a particular soil mix to prevent waterlogging and improve drainage. Regular potting soil is unsuitable for these plants, especially if you plan to keep them indoors. Garden soil is also not ideal as it typically doesn’t drain well enough. It may also carry weed seeds, pests, or diseases to your plant.

Always choose a specialized succulent and cacti potting mix when planting in containers. These mixes are formulated with the right materials to improve drainage and provide the gritty texture these succulents love. If you want to make your own mix, you can also amend potting soil with sand and perlite.

Soil is typically only a consideration when repotting, and even that is a rare occurrence. Try to replicate the current soil texture as much as possible when repotting. This will help you ensure the plant will be happy in its new home and that there will be limited issues with transplant shock.

In outdoor containers for plants in full sun, you won’t need as much drainage as the soil will dry out quicker. However, it’s still important to keep the right texture and plant in a container with plenty of drainage holes to avoid issues with overwatering.

Temperature and Humidity

In addition to overwatering, this plant can’t handle cold temperatures. Originating from warm native environments where temperatures rarely dip below 60°F, they are not at all cold tolerant. They can quickly die if left in the cold for too long.

Only those living in USDA Zones 10 and up should consider keeping coral cactus outdoors. This protects them from any potential cold damage from chilly nights or frost. Temperatures can drop to around 50°F before any serious damage occurs, but it’s still better to keep the temperature consistently above 60°F throughout the year.

If you live in a colder region, you can always bring your potted succulent indoors for fall and winter. Alternatively, many gardeners keep them indoors throughout the year to grow as houseplants. Although the conditions aren’t ideal indoors, this helps limit shock from moving the plant indoors and out twice per year and drastically changing environmental conditions.

Humidity is not much of a concern for these succulents. They typically prefer drier air, not requiring humidity to thrive like other houseplants. High humidity can lead to the growth of diseases like powdery mildew, so watch for potential issues if you live in a high-humidity area.

Fertilizing

Coral cactus is a slow-growing plant that doesn’t need much fertilizer to thrive. But, like any plant growing in containers, nutrient levels will eventually dip. A light nutrient boost is always helpful.

A balanced general fertilizer is recommended. I suggest applying at half strength to start to avoid over-fertilizing. Do this around once every 6-8 weeks or so in spring and summer. Stop fertilizing in the fall and winter to give the plant a break.

Propagation

Coral cactus is a combination of two different species, so it can’t be propagated in the ways other succulents can. In order to make more of these unique plants, you’ll have to graft new ones from separate Euphorbia neriifolia and Euphorbia lactea var. Cristata species.

Grafting is a tricky process that can get quite technical. It’s far easier to purchase a brand-new plant than to propagate it. If done incorrectly, grafting creates the risk of disease or rot, and there is the potential that the graft may not heal correctly, impacting later growth.

How to Graft Coral Cactus

Start with a healthy Euphorbia neriifolia and Euphorbia lactea var. Cristata species for the best chances of success. Sanitize a sharp knife to avoid transferring any harmful bacteria when cutting. Start by cutting a V shape into the Euphorbia neriifolia stem downwards. Avoid a straight cut that could cause the top to tip over before healing.

Next, cut an arrow shape exactly the same size into the bottom of the Euphorbia lactea var. Cristata crest, so the two pieces fit together. Lower the top species onto the base plant so they fit well together. There should be no gaps between the two sections, as this can negatively impact healing and increase disease risk.

Tie the two sections together with twine or secure them with grafting tape to keep the cut surfaces touching. Place the plant in a bright spot to heal. Water as usual, when the soil has just dried out.

After several weeks, the cutting will heal. At this point, the twine or grafting tape can be removed to continue growing as usual.

Repotting

Frequent repotting is not a concern because these plants are slow growers and don’t grow much bigger than their initial grafting size. It will be happy in its existing pot for several years without showing signs of struggle.

However, as the soil degrades over time, it is helpful to provide a soil refresh every three to four years. Simply replant in the same container. You can also repot if you want to change the container to improve drainage or aesthetics.

It’s best to repot during spring and summer. Optionally, choose a pot one size up to provide a little more space. Ensure you use the same soil mix when repotting to keep conditions consistent.

Common Problems

There are a few common problems to look out for, especially if you want to keep this unique succulent alive as long as possible. Some are easier to fix than others.

Branches Sprouting From Base

This issue is common among coral cactus owners and luckily is not a cause for concern. Extra branches sprouting from the base of the plant (Euphorbia neriifolia) are simply the plant’s natural growth processes. You can keep this branch on the plant if you like or trim it off to return to its original shape.

Wrinkling

Wrinkling can be a sign of drought conditions. Due to the ‘cactus’ in the name, some gardeners may assume these plants need very little water. While they do need less water than other houseplants, they still don’t like dry soil for long periods. Without moisture, the stems shrivel and develop wrinkles until you water the plant.

Wrinkling can also be a sign of overwatering, but this is usually accompanied by other issues like mushy stems and yellowing. Hold off on watering for a while and repot if you suspect any cases of root rot.

Yellowing

A yellowing succulent is another sign of overwatering. It is not particularly common, but can happen if there is not enough drainage. This can also occur if you often water when the top layer of soil is still moist. Yellowing combined with soft stems indicates a serious problem, requiring quick repotting and trimming of the roots if you want to save the plant.

Pests

Coral cactuses are susceptible to a range of pest issues, including spider mites, scales, and mealybugs. This is very common. I’ve had the bad luck of dealing with mealybug infestation on every one of my Euphorbias at some point. Some pests are easy to pick off yourself. However, if the infestation is severe, you should spot-treat with rubbing alcohol for a few rounds until all the bugs are gone.

There are also a few diseases to watch out for, such as powdery mildew and root rot, but these are far less common. Provide the right care and tackle any issues as soon as they pop up to prevent spread.

Frequently Asked Questions