This colourful star brightens any winter garden
The members of the euphorbia family are among the stars in the winter garden. We've all been admiring the brilliant red poinsettias and the white snowflakes that have been putting on such a great show for the past few weeks.
Another euphorbia, probably less well known but just as stunning, is the euphorbia millii, or crown of thorns. This plant from Madagascar is a succulent, with stems adapted for water storage.
It has vicious looking thorns on the stems and branches, and flowers profusely for most of the year. Colours range from white through pastel yellows and pinks to vibrant reds.
The grey-brown stems are not round but have five to seven sides and many prominent grey thorns a couple of centimetres long. The leaves are smooth and oval shaped, and range in colour from bright green to greyish green.
Euphorbia millii are very popular in Thailand, where they are known as "poysean" (Chinese for eight saints), since the original forms typically have eight flowers in each bunch.
The eight saints each represent a different force - health, bravery, riches, beauty, art, intelligence, poetry and ability to overcome evil. Poysean plants are believed to help bring these positive forces to the home and its occupants.
Perhaps because of the popularity of this plant in Thailand, thousands of hybrids have been developed there. The Thai hybrids tend to have larger flowers, thicker stems and a more upright and compact form.
Euphorbia millii need a well-drained, warm spot in full sun. They look great in a pot, and can live in one for several years. Use premium potting mix or one formulated for cacti and succulents and make absolutely sure the pot can drain freely.
If the pot has a saucer, be sure to tip out excess water, and don't let the plant sit in water for any length of time.
These plants are drought tolerant and it is important not to over-water them, particularly in cool weather. Indeed you should allow the top few centimetres of soil to dry out between waterings.
Euphorbia millii are not bothered by many pests or diseases. Most problems are caused by too much water and/or inadequate drainage.