The Giant marsh marigold (Caltha polypetala) is the larger cousin of the British native Marsh marigold and grows to around twice its size so therefore is not suitable for small ponds.  These early flowering spring perennials bring a splash of colour into the garden from as early as March but are at their best in April.  They have large yellow buttercup-like flowers with glossy green leaves making a spectacular addition to pond margins and bog gardens and quickly grow to form large clumps which are easily divided to provide new plants in spring or autumn.  If cut back after flowering you may get a second flush of flowers in the summer.

Calthas grow well as either marginal or bog garden plants making them very versatile.  As marginal plants, they will grow up to 20cm (8ins) underwater and can grow up to 100cm in height. A valuable plant providing early nectar for bees and butterflies emerging from hibernation.

Caltha a yellow flowered plant; palustris of the marshes

Height: 60-100cm

Spread: 60cm

Planting position: Pond marginal shelf up to 20cm deep; or very wet soil

Form: 3 litres in an aquatic basket