Succulent euphorbias need to grow in a place that is always bright, although this does not necessarily mean full midday sun! In habitat many euphorbias survive in full sun, but the roots are usually in a relatively cool soil often under rocks. In a pot on a south-facing windowsill, the soil can be much warmer.

Some euphorbias “remember” the seasons of the southern hemisphere and grow in our winter months. For these we recommend artificial lights to supplement normal daylight, programmed to switch on an hour before sunset and remain on for up to 4 hours. Normal room lighting does not have the right spectral values for plant growth. The so-called “Truelight” light-bulbs give off little light and are only really suited for situations where the plants stand right under the lights, but even so the light production drops off sharply in the second year. The best results are achieved with mercury vapour bulbs and high pressure sodium vapour bulbs. However as they get very hot they are not appropriate for small-scale applications, but are better suited to large greenhouses, also bearing in mind their high cost.

Euphorbia mammillaris