Euphorbias are the perfect perennials. While some are as exotic-looking as the rarest succulents and just as drought tolerant, others tastefully blend in when used in a mixed border scenario. They come in just about any colour imaginable, from burgundy verging on black to a brazen flaming orange and there isn’t a season when one can’t find a member of this plant family to brighten your garden. So I thought we’d do a tour of the family Euphorbiaceae so that you too can appreciate the depth that these perennials can bring to our landscapes.
Although normally perceived as full sun lovers, several thrive in open shade to part sun exposures. The best of these are the Wood Spurges (Euphorbia amygdaloides) which can form dense colonies that act as tall groundcovers. Purple Wood Spurge (‘Purpurea’) features eye-catching reddish-burgundy foliage, while Mrs. Robb’s Bonnet (var. robbiae) bears leathery deep green whorled leaves with both of them producing contrasting yellowish-green blooms from mid to late spring.
At the other end of the size spectrum is the massive Euphorbia characias subsp. wulfenii or Mediterranean Spurge, which is used extensively in city street plantings and parks. This imposing evergreen perennial grows up to 3’ tall with striking bluish-green foliage, covering themselves in terminal clusters of chartreuse bracts from late March into June. Wulfenii fits perfectly into tropical-themed gardens or even a mixed border, where it pairs nicely with Berberis t. ‘Rose Glow’. Compact forms can also be found in ‘Shorty’ and ‘Humpty Dumpty’, with both averaging 2-3’ tall and like the species, preferring sun with good air circulation and adequate soil drainage.
Of equal stature but herbaceous in nature (dies down in winter) is one of my favourites, Euphorbia griffithii. There are basically two common cultivars, ‘Fireglow’ and ‘Dixter’ (tan stems), which are quite similar with both bearing stunning fiery orange bracts (with tiny yellow center flowers) starting in early summer. They grow an average of 3’ tall and can form sizeable spreading clumps over time, but that works well in larger landscapes, particularly in the back of a perennial border. Both Euphorbia schillingii and ‘Excalibur’ (a cornigera x schillingii hybrid) have a similar height and growth habit but with deep green leaves highlighted with a prominent white rib and very showy lime green summer flowers.
Euphorbia characias 'Humpty Dumpty' with Bluebells, Euphorbia characias subsp. wulfenii with Berberis 'Rose Glow', Euphorbia x 'Excalibur', Euphorbia griffithii 'Dixter', Euphorbia griffithii 'Fireglow' in mass, Euphorbia schillingii.
Autumn is a very popular season for Euphorbia, particularly the variegated forms which are evergreen and work well in winter planters. The most common of these are ‘Tasmanian Tiger’ (pale gold leaf margins) and ‘Glacier Blue’ (frosty blue foliage with cream edges) both of which are hardy to USDA zone 7, although I find the latter more resilient in cold snaps. ‘Helena’s Blush’ and E. x martini ‘Ascot Rainbow’ bring a kaleidoscope of foliar colour (gold, green and burgundy) to the garden palette which intensifies with the cold, and the variegated spring blooms are nothing short of spectacular. ‘Silver Swan’ is a newer variegated introduction while ‘Blackbird’ (a sport of ‘Redwing’) provides purplish-black foliage that contrasts well with evergreen grasses such Carex ‘Evergold’ or Acorus ‘Ogon’.
Late winter brings out the best colouring in both Euphorbia x martinii ‘Rudolph’ and ‘Efanthia’ (an amygdaloides hybrid) which are primarily a deep green colour, developing intense reddish-purple growth tips in the colder weather. Come spring you can enjoy two species of Euphorbia in your rock garden, starting with Donkey-Tail Spurge (E. myrsinites) with its cascading evergreen whorled blue branches which terminate with chartreuse blooms. The herbaceous Euphorbia polychroma or Cushion Spurge is no less showy, forming a tight mound (12-18” tall and wide) of chrome yellow flowers from April to May, with ‘Bonfire’ bearing multicoloured foliage.
Euphorbia 'Ascot Rainbow', Euphorbia 'Blackbird', Euphorbia 'Efanthia',
The good news about Euphorbia is that they are all deer and rabbit resistant due to their milky sap, however some species (such as E. myrsinites) can burn skin and should be handled with gloves. Pests are infrequent, with aphids occasionally attacking bloom bracts, but this is easily handled with a spray of an organic pesticide such as Trounce. Herbaceous forms can be cut back in fall when they die down, while evergreen types are pruned to their base (look for those new shoots) after the flowers fade and rejuvenate entirely. The number one killer of Euphorbia is poor drainage, so avoid these areas when planting.
Well that ends our whirlwind tour of the Euphorbia family, with the best part being that no matter when you decide to visit the garden centre, there’ll be one waiting for you to bring home.
All images Copyright to Mike Lascelle 2015-2020