African Cathedral Cactus

African Cathedral Cactus (Euphorbia heterochroma) is a succulent spurge from east Africa, not a true cactus, grown for its upright columns of mottled green and red stems. It builds slowly to about 1.5m tall and 1m across, branching into a candelabra shape that holds a courtyard on its own. Small yellow flowers appear along the ridges in the warmer months.

Why you'll love it

• Architectural from day one. The vertical ribbed stems give a clean sculptural line that suits modern paving and rendered walls.
• Stem colour that shifts with the sun. Green columns flush red and bronze in strong light, so the plant changes tone without flowers.
• Genuinely tough. Heat tolerant, drought tolerant and happy in poor soil, it holds up through a dry summer unattended.
• Slow and predictable. It will not outgrow a pot or a rockery in a hurry, which makes it easy to place.

Where it works best

Pots and courtyards. A heavy pot 400mm or wider gives the stability tall stems need. Cactus and succulent mix, full sun, and almost no watering through winter.

Rockeries and gravel gardens. Plant it high in the rockery where drainage is sharpest, with low succulents around the base to set off the height.

Feature planting. In a hot, dry bed one plant carries the whole composition. Keep it well back from paths and play areas because of the sap.

Growing African Cathedral Cactus in Australia

Position and climate. Full sun brings the strongest stem colour and the tightest growth. It suits tropical, subtropical, warm temperate and arid gardens. It is frost tender, so cool temperate and frost prone gardens need it in a pot that can move under cover, or in a bright position indoors over winter.

Soil. Sharp drainage above all else. Use a cactus and succulent mix in pots, or open heavy soil with coarse sand and gravel and plant on a raised mound. Poor, stony ground suits it better than a rich bed.

Water and feed. Water only when the mix is dry right through, roughly every three weeks in summer and once a month or less in winter. Feed a half strength liquid fertiliser twice over the growing season, no more.

Handling and pruning. It rarely needs cutting. When you do prune or repot, wear gloves and eye protection, because the milky sap is caustic and burns skin and eyes. Wash any contact off immediately with soap and water.

What to expect when it arrives

It is sold as tube stock only, so your plant arrives young, usually a single stem 10cm to 20cm tall. It takes several years to build the branched candelabra shape. Potting it up in stages, rather than straight into a large pot, gives the best result.

Succulents travel well because there is nothing to wilt, and small marks from packing grow out. Leave it dry for a week after unpacking before the first water. Delivered Australia wide, delivery from $29.95, with our 30 day healthy plant guarantee.

Plant care guides and related reading

• Low maintenance cacti for a front garden
• Browse the cacti collection
• Succulents for hot and dry climates
• Plants for rockeries and gravel gardens

Common questions

Is the sap dangerous?

Yes. The milky latex is caustic and toxic to people and pets, and it can cause serious eye injury. Wear gloves and glasses when handling it, and plant it away from children and animals.

Is it actually a cactus?

No. It is a euphorbia that has evolved a cactus like form in a similar climate. The care is much the same, but the sap makes it a very different plant to handle.

How fast does it grow?

Slowly. Expect a few centimetres a year in the ground and less in a pot, with branching once the main stem has real height.

Can I grow it indoors?

Yes, in the brightest window you have, and it is the sensible option in a cold garden. Water sparingly and turn the pot to keep the stems straight.