Plant Love: Euphorbias

07.07.2017

Plant Love: Euphorbias

Poinsettia’s unexpected relations

The common Poinsettia with the brilliant and oversized dark-red flowers that is sold at Christmas time doesn’t look a bit like it’s related to the cowboy cactus. Welcome to the wonderful world of Euphorbia. The family is a big one. With about 2000 members, it’s one of the biggest families of flowering plants. Most share good looks, sun-hardiness and drought-tolerance. And all share a milky white sap in the stems that can cause skin irritations. It’s best to wear gloves and long sleeves when pruning and repotting, but that is pretty much the only effort required. These are easy-care, great plants. Our favourites include these three:

Euphorbia acruensis ‘Cowboy’

The Tex-Mex vibe gives this Euphorbia its common name, Cowboy Cactus. (Below right)  It thrives in Sydney’s mild climate, and will do well in either full sun or some shade, so suits balcony gardens, courtyards, and even indoors in a well-lit well-ventilated space. It will get to 1.5 m in a large enough pot, but given a choice, buy it at the size you want to keep it, as it’s not an easy job to repot it – the spines are sharp, and like all Euphorbias the sticky white sap can be a skin-irritant. The big risk in growing this plant is overwatering, which will cause it to rot. Let the mix dry out completely before using the watering can.

Euphorbia hybrid ‘Diamond Frost’

This is one of those magic plants that is almost always in flower, with airy white flowers hovering over the bright green foliage as if a host of butterflies was looking for landing space. It grows in sun or shade, though it flowers best and is more compact in more sun. Diamond Frost (Above left) grows into a mound about a metre high and wide, but can be trimmed to make it more compact. Use shears to trim the whole plant in the warm months, wearing long sleeves and gloves to protect against the sap. It works as a filler in between and under other plants, offering a good textural contrast to more architectural plants. It is just as happy in pots or hanging baskets as it is in the garden. Once established in the garden it needs little extra water, though it will need to be cared for when growing in pots.

Above: Euphorbia tirucalli

Euphorbia tirucalli

The original green version of this succulent is called pencil cactus, for the cactus-like, pencil-thin branches that stick up like so many waving fingers. We love its sculptural look and the clear green colour, though there is another version, commonly called ‘Firesticks’, which is also popular. New growth in ‘Firesticks’ is gold, intensifying to rich orange in the cold weather. Euphorbia tirucalli grows well in containers or in the garden, and if left untrimmed can get to three metres tall. Trim a little bit often to maintain a compact plant.

 

Robin Powell

Images: Nicholas Watt; Richard Unsworth.

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