Good winter foliage is a rare thing in the garden, but some euphorbias produce handsome rosettes that can endure in the hardest weather. Others retreat underground and rise up again in the spring, from asparagus-like shoots. It’s not surprising that there’s so much diversity.
The genus Euphorbia is the second largest in the world with over 2,000 species ranging from stunning garden plants to cactus like trees found in Africa.
Where to plant
Foliage varies from green, through to variegated, to metallic gun-metal grey. Generally the ones with silvered succulent like foliage need very sharp drainage and an open position and are best planted on scree beds, the sunny front of a border, or on rockeries.
Green-leaved euphorbias with winter rosettes generally prefer woodland shade and flower in spring.
Ones with grey-green leaves, often with the Mediterranean E. characias in their bloodline, are sun-lovers. There are variegated form and these need more light to grow well, because the green area that produces chlorophyll is reduced.
Wintergreen euphorbias need to be kept compact. Cut them back after flowering so that they produce lots of new basal shoots. This will keep them vigorous and prolong their life, although all euphorbias tend to only live for four to five years on average.
The fact that they self-seed often provides new plants. They also produce sports, shoots that vary from the parent plant, and this has produced a supply of new varieties - especially variegated forms.
After cutting back new basal growth appears and this makes perfect cutting material. Take pieces that are between two and three inches.
Trim off the lower leaves and plunge the cuttings into small trays or pots of coarse horticultural sand. Pot up singly once rooted.
Silver-leaved succulent-like euphorbias for good drainage
This low-growing, silver-leaved, succulent-like euphorbia is perfect for a free-draining scree bed, or front of the sunny border. The spidery arms loll over the ground and produce an acid-yellow topknot of flowers in April.
More erect and sharper-leafed, this euphorbia spirals up as it flowers rather like a snake being charmed. Looks almost metallic in winter light.
Variegated euphorbias for good light
Variegated euphorbias really stand out in winter light because the soil is very dark. Many are micro propagated and readily available in garden centres, although the new ones seem to replace older varieties every year.
Variegated euphorbias have been short-lived in the past, but they make excellent container plants for winter. Really vicious winters kill them, so in colder parts of America they are grown as summer container bedding.
The brightest of all, this form of the Mediterranean spurge Euphorbia characias has grey-green leaves margined in cream. Cream and grey-green flowers follow, rather than the usual limy yellow. It was first spotted in 1993 by an Australian plantswomen in a cultivated area of Tasmania - hence the name. It’s now widely available in America, Canada and Britain and it’s love at first sight for most people.
Much subtler, with long, slender grey-green leaves finely edged in cream. Said to be much hardier than ‘Emmer Green’ and the similar ‘Silver Swan.’
A very bushy form with distinctive blue-grey foliage raggedly edged in cream. A sport of ‘Tasmanian Tiger’, it was found at and introduced by Skagit Gardens in Washington State, is said to have much better vigour.
The silver Mediterranean spurge for hot spots
The Mediterranean grey-leaved species, E. characias, makes a very handsome winter plant in sunny, well-drained spots that are sheltered from the worst of the weather. The cottage gardener Margery Fish, who gardened at East Lambrook Manor in Somerset, likened their crook-shaped winter stems to “a flock of long-necked birds”. (From “Carefree Gardening” by Margery Fish -published in 1966). By midwinter these tall, billowing plants are already craning their necks before producing acid-yellow flowers in spring. These self seed if left to their own devices.
Our own native wood spurge, Euphorbia amygdaloides, loves a dark woodland setting and grows wild close to my Gloucestershire home. There is a selected beetroot-leaved form called ‘Purpurea’ that will provide a sorbet of lime-green flowers and maroon leaf in spring. ‘Craigieburn’ is the finest purple form, with wide rosettes, but it’s difficult to find.
A hybrid between a woodland spurge E. amygdaloides subsp. amygdaloides and the Mediterranean E.characias occurred naturally in France and produced a stocky euphorbia with soft grey-green foliage and lime-green ‘flowers’ studded with tomato-red stars. These were named E. x martini and there are some fine forms including ‘Helen Robinson’, named after the original founder and owner of RHS Hyde Hall’s garden in Essex.
‘Helen Robinson’ may be a hybrid with Mrs Robb’s bonnet, more correctly called E. amygdaloides var. robbiae. Mrs Robb was a rather grand lady and the granddaughter of Lunar Society member Matthew Boulton. She travelled through Turkey in 1891 by stage coach. On the way home she noticed a splash of gold on a hillside near Istanbul. She alighted and tucked a piece of the plant into her empty hat box, after quickly reinstating her bonnet. William Stearn, writing in 1973, says that she cultivated the plant successfully in her garden and shared it with friends.
Euphorbia ‘Whistleberry Garnett’ has wide low-growing rosettes which display red undersides in winter. It appeared as a seedling in the garden of Tessa Hobbs, a garden designer, circa 1995.