A small family of stout, hardy marginal perennials, with bright yellow or white flowers in spring. Grows well in marshy ground, often near streams. It may either be erect or creeping in form.
Family: Ranunculaceae (buttercup)
Botanical Name: Caltha
Common Names: Marsh marigold, kingcup, bull flower, golds, cow lily, water buttercup.
Foliage: Evergreen, broadly heart-shaped, round or pointed, green leaves.
Flowers: Clusters of buttercup-like yellow or white flowers. Single or double forms are available.
Flowering Period: Early to late spring.
Soil: Moist, poorly-drained soil (clay or loam). Any pH.
Conditions: Best in full sun. Plant in a west or south facing aspect.
Habit: Bushy, clump forming.
Type: Rhizomatous herbaceous perennial.
Origin: Northern hemisphere.
Hardiness: Hardy in most regions of the UK.
Easy to grow. Thrives at the margins of ponds or in boggy ground. Best grown in an open, sunny aspect.
Plant out between spring and autumn in wet soil or in aquatic containers in around 6in (15cm) of water.
Ideal for the edges or ponds, streams, lakes or water gardens.
The roots must be kept moist all times.
Marsh marigolds can be cut back and tidied up around the end of May, once flowering has finished. This may produce a second flush of flowers in warm summers.
Generally pest and disease free. Although rust fungus may be a problem in some areas.
Separate mature clumps after they have finished flowering, in late spring and replant immediately.
Caltha palustris (marsh marigold) has cup-shaped, golden-yellow flowers, early in the spring. It grows in water up to 6in (15cm) deep. Height to 24in (60cm). Available from Thompson and Morgan.
Caltha palustris 'Plena' is a smaller, more showier variety with double flowers. Best as a marginal plant. The variety 'alba' is a white form that blooms in early spring.
Caltha polypetala (Giant marsh marigold) has heart-shaped leaves and deep golden flowers. Height to 24in (60cm).
Caltha leptosepala (Western marsh marigold, white marsh marigold) has rounded broad, light green leaves and starry late spring flowers. Usually white with a yellow centre.