Caltha palustris

Caltha palustris is believed to be one of our most ancient native plants. It may have been growing since before the last Ice Age and, after the retreat of the icecaps it proliferated across the watery landscape. It is a spectacular-looking, hardy perennial plant, with large rich yellow flowers, each with five petals, and shiny green, heart-shaped leaves borne on long, smooth hollow stems.
It is in flower from March to August, and is one of the first plants to appear. It has been long regarded as a herald of spring. The plant’s yellow flowers and dark green shiny leaves cheer up the otherwise barren landscape as winter recedes. In a number of places it was the centre of a custom known as ‘bringing in the mayflower’. The flowers were scattered over doorsteps on the eve of May Day.

Caltha palustris, commonly called Marsh Marigold is one of the most cheerful native plants to adorn the edges of a pond or stream and possesses the added benefit of flowering in the shade.
This wet-footed, rich soil-loving, versatile plant grows in a pleasing, compact habit while the height ranges from 20 to 60cm (8 to 24in) tall. The heart shaped, glossy green leaves up to 18cm (7in) in diameter attain mature size in summer well after flowering.
The delightful yellow flowers which grow to around 2 to 5cm (1 to 2in) in diameter, with 5 to 9 waxy deep yellow petal-like sepals are also likely to be the first pond plants to bloom in the spring.

Marsh Marigold loves any rich soil that’s damp to fully submerged, and will thrive and bloom in part sun to shade, which is always a much appreciated characteristic in the water garden because most flowering plants used in water gardens prefer full sun.
It is good for colonising areas to encourage wildlife as it gives plenty of habitat opportunities and will spread by seedlings if allowed to. Marsh Marigold are loved by hoverflies, bees and butterflies when in flower later in the summer.

• Awarded the RHS Award of Garden Merit
  Caltha palustris has been awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).

Sowing: Sow in late summer/autumn or late winter/late spring
Sow at 18 to 22°C (65 to 70°F) in a well drained compost mix. Cover with vermiculite. Water from the base of the tray, keeping the compost moist but not wet at all times. Germination should occur in 21 to 28 days but is occasionally a little longer.
Prick out each seedling once it has its first set of true leaves, transplant into 7.5cm (3in) pots or trays containing a peaty soil. Grow on under glass. Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out in spring. Plant 40cm (15in) apart.

Cultivation:
Grow in full sun to part shade in shallow water at the margins of a pond or water garden or in wet, boggy soils. Best flowering usually occurs in full sun, but in hot areas, plants appreciate some part shade in the heat of the summer. If sited in full sun in hot summer climates the plants may go dormant in summer.
The plants can be situated in wet mud in a stream edge/bog garden or with up to 10cm (4in) of water over the top of the basket in a sunny or partially shaded pond.
Cut back leaf growth after Caltha palustris has flowered and allow fresh foliage to regrow - old leaf growth can become grey in colour. A second flush of Marsh Marigold flowers may appear later in the season. Divide plants in early spring before blooming or in the summer when almost dormant.

Plant Uses:
Ponds, streams and damp areas. Wildlife

Origin:
This plant’s range can best be described as circumboreal, meaning ‘around the north’. Marsh marigold is found across most of the UK and Europe (although rare in Mediterranean regions), Northern Asia and large parts of North America. It is a plant of marshy meadows, wet flushes and ditches, from the lowlands to the uplands.
Caltha palustris is familiar to Finns on ditch banks, but it is equally familiar to Australians, Americans and even inhabitants of the East Indian archipelago. In North America it can be found in marshes, swamps, wet meadows and stream margins from Newfoundland to Alaska south to Nebraska, Tennessee and North Carolina.
Although marsh marigold declined somewhat in Britain and Ireland through drainage of land for farming during the 1970s, its distribution has changed little. The withdrawing of agricultural grants for draining wetland stabilised this decline, and there is no perceived threat to its survival as a native species.
The wide distribution of the plant shows that it is ancient, as does the primitive structure of the flower. Although Marsh marigold is not known as a fossil, it can be justifiably termed a living fossil. It is not however encumbered by its age because it changes and adapts to ever-changing conditions.
It is a flowering plant of the family Ranunculaceae.

Nomenclature:
The botanical name, Caltha derives from the Greek kalathos and means cup
The species name palustris means boggy or marshy. “Marsh Cup” or “Cup of the Marsh.”
Its common name, ‘Marigold’ comes from a corruption of the Anglo-Saxon term merso-meargealla which means literally 'marsh gold.' This etymological detail was apparently lost on whoever coined the term 'Marsh Marigold' which is obviously redundant with the word Marsh added back into the name again.
The name ‘Marigold’ has also been associated with the Virgin Mary (Mary Gold) and with Britain’s 16th century monarch, Mary I (Queen Mary).
Unfortunately, the name marsh marigold is only descriptively accurate as to this plant’s habitat, because it neither looks like nor is related to marigolds (Aster family). It belongs to the buttercup family, Ranunculaceae and its shiny yellow flowers indeed look very much like buttercups.
Other common names for Marsh Marigold include Cowslip, Kingcup and Cowflock. In Britain, it is known by a number of common names which may be unfamiliar to some gardeners, such as Mayflower, May Blobs, Mollyblobs, Pollyblobs, Horse Blob, Water Blobs, Water Bubbles, Gollins and the Publican