June is a sublime month in the garden with a huge range of plants enjoying the long days and looking resplendent at the peak of the gardening year. Not commonly grown but worth looking out for is Euphorbia cornigera, which is a lovely herbaceous perennial.
Although the spurges (the common name for Euphorbia) primarily flower in the spring, Euphorbia cornigera looks at its best in mid-summer when it reaches around 1.2m (4ft) tall and 60cm (2ft) across. It is self-supporting and doesn’t usually need staking unless the rainfall is high or the soil is rich and it puts on lots of lush growth. This is one of the best euphorbias as it has very attractive foliage and it can be used through a planting scheme as a ‘foil’ for other strongly coloured plants. It also contrasts particularly well with dark purple or blue-flowered plants.
As well as very floriferous plants, a successful planting scheme also needs ‘foliage’ plants that add a calming influence to a combination. This Euphorbia achieves this through its foliage, which consists of narrow, dark green leaves, which have a very prominent white central midrib and striking white veining running through the leaf. Its flowers are borne during mid-summer when involucres of tiny bright lime-green flowers open and are surrounded by small, bright green bracts, creating a very fresh and zingy feel to any planting scheme.
This Euphorbia likes deep, humus-rich and moisture-retentive soil that doesn’t dry out during the summer months. It also prefers part shade but it will tolerate full sun as long as the moisture remains in the soil throughout the summer. It is easy to maintain and we cut the old growth back in the early spring months as the new growth begins to come through from the base of the plant.
At RHS Garden Hyde Hall you can find Euphorbia cornigera flourishing in the Robinson Garden where it enjoys the moisture-retentive soil and associates well with perennial geraniums such as Geranium phaeum ‘Lily Lovell’, an attractive cultivar with violet flowers that have a white centre, and perennials such as Astrantia major subsp. involucrata with its dark maroon, pincushion-like flowers.
Towards the back of a border, Euphorbia cornigera also works well with Sanguisorba, a tall perennial with small egg-shaped flowers, which are dark red if a cultivar such as ‘Arnhem’ is selected. This Euphorbia also works well in a mixed border where it can be repeated through a scheme as a linking element and it contrasts well with perennial salvias such as Salvia nemorosa ‘Lubecca’ with their dark purple flowers.
More on euphorbias
Discover more plants from the spurge family
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