Many euphorbias come to the fore in spring and early summer, adding to the wide array of colour in gardens. They range from species that enjoy sunny and arid situations, to others that conversely enjoy damp and boggy conditions.
Euphorbia palustris (marsh spurge) belongs in the second category, as it enjoys growing in soil that stays permanently moist. Luckily, though, it will tolerate a degree of dryness and will grow in a mixed border in moisture-retentive soil, as long as the soil doesn’t dry out in summer.
Although it likes moist soil, it also prefers the sun rather than shade, and is well-suited to growing around a pond where the soil stays moist throughout the year. Euphorbia palustris is a robust, clump-forming perennial and, as its new shoots emerge from the plant's base in mid spring, they form into bright yellow flowerheads, 15cm (6in) across.
Bright and bushy
Each individual flower is tiny and is surrounded by a modified petal, which is what gives the plant its bright yellow appearance. When the flowerheads first develop, the plant is quite small, but as they continue to grow the plant will reach around 90cm (35in) tall by the time the flowers fade. The narrow leaves of this euphorbia are bright green with a pale white midrib, and as autumn progresses they turn shades of yellow and orange.
Cut the stems down to the base of plant in winter, before new growth emerges in spring. At Hyde Hall we use E. palustris in areas such as the Upper Pond in the Hilltop Garden, where it forms stately clumps on the margins of the pond, adding zesty, fresh colour to the planting in late spring.
Plants that associate well with this euphorbia include Iris sibirica ‘Perry’s Blue’ with its pale blue flowers, and astilbes with their feathery pink flowerheads. For lower-growing plants around the base, consider using geraniums such as G. macrorrhizum ‘Czakor’, or G. sanguineum. We’ve also used this euphorbia in the herbaceous border where it fits beautifully in the white, lemon and green colour combinations. Even after it has finished flowering, its bright green foliage adds valuable structure and freshness to the planting.