Euphorbia hypericifolia 'Diamond Frost' grows to a 50cm cushion and is spangled almost all year round with tiny, white flowers. It is a tough plant, coping with drought and heat, and flowering best in full sun - although some gardeners report it also blooms quite well in shade, even under trees. It can grow quite wide, so I occasionally chop it back hard to control its girth. It is great for filling in a bare area quickly! It does self-seed a bit, but I have not yet found it to be a problem. The species name of this one is a bit hard to pin down, but it seems to be a form of the African plant Euphorbia hypericifolia - a common weed in Europe and the USA. It is a great filler between other plants. I enjoy seeing it contrasted with very dark leaves (as illustrated above) but it is a suitable partner for almost any other plant in the garden. I like seeing it grown nearby bold white flowers, such as daisies; or near foliage with white flecks or markings. It could even be grown as an informal hedge!
My plant survives the occasional frost (one or two light episodes per year); but in very cold areas, it should be grown as an annual, or potted up and kept under cover in winter. In fact, it is a great plant for a large pot and can be shaped into a sphere, as illustrated at left; or it can be grown in a hanging basket. I have seen a miniature version of the plant, called 'Diamond Dazzler', which might be more controllable than the usual form!
All Euphorbia have an irritant sap in their stems so take care when handling these plants and always wear gloves when pruning. Be very careful not to get any sap in your eyes as this can cause damage to them.