Giant King Cup (Caltha palustris ‘Polypetala’)

Giant King Cup | Caltha palustris ‘Polypetala’

Large flowering marsh marigold with bold golden blooms for pond margins

Giant King Cup, also known as the Giant Marsh Marigold, is a stunning, larger growing variety of the much loved native marsh marigold. This impressive marginal plant produces an abundance of rich golden yellow flowers that bring instant colour and brightness to pond edges, streams, and bog gardens early in the season.

Flowering from April through to June, and often into early July in cooler conditions, the bold buttercup style blooms sit proudly above lush, glossy green foliage. These vibrant flowers are not only visually striking but also highly attractive to pollinators such as bees, making this plant a valuable addition to any wildlife friendly pond.

Compared to the standard marsh marigold, Caltha palustris ‘Polypetala’ offers larger flowers, more vigorous growth, and a stronger visual presence. Its rounded, deep green leaves form a dense clump that provides excellent ground cover, helping to suppress weeds and stabilise damp soil around pond margins.

This plant thrives in shallow water or consistently moist soil, making it perfect for marginal shelves, wetland planting, or natural pond edges. It performs best in full sun where flowering will be at its most prolific, although it will also tolerate partial shade. Once established, it is incredibly reliable and low maintenance, returning year after year with very little input required.

Giant King Cup is particularly beneficial for pond ecosystems. Its dense foliage offers shelter for amphibians such as frogs and toads, while its early flowering period provides an important food source for pollinators emerging in spring. It is an excellent choice for both ornamental and naturalistic planting schemes.

Due to its size and spread, it is best suited to medium to large ponds or areas where it has room to develop fully. Regular division will keep it healthy and ensure it continues to perform at its best.

Please note this plant is toxic if ingested and should be handled with care.

🇬🇧 UK-grown aquatic plant: Grown at a dedicated aquatic plant nursery in the South of England and carefully prepared for delivery across the UK.

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Key Benefits

• Large, vibrant golden yellow flowers for strong visual impact
• Early flowering adds colour when ponds need it most
• Excellent for pollinators such as bees
• Provides shelter for amphibians and pond wildlife
• Dense foliage helps stabilise pond edges
• Fully hardy and very reliable in UK conditions

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Reasons to Buy

• Bigger and bolder than standard marsh marigold
• Ideal for wildlife ponds and natural planting schemes
• Easy to grow and low maintenance
• Perfect for adding early season colour
• Suitable for pond margins, streams, and bog gardens

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Care Instructions

• Plant on a marginal shelf at a depth of 0 cm to 20 cm, or in consistently moist soil. Depth is measured from the top of the basket to the water surface.
• Position in full sun for best flowering, although partial shade is tolerated. Keep soil or planting area consistently moist.
• Divide clumps every few years in early spring to maintain vigour and prevent overcrowding. Remove spent flowers to encourage a longer display and cut back foliage in autumn to keep the plant tidy.

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Flowering Period

April to July

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Size and Growing Conditions

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Dispatching Your Pond Plants

Your Giant King Cup will be carefully packed to protect the foliage and roots during transit.

Orders received by 11am Monday to Wednesday are normally dispatched on the following working day using a next working day courier service. During busy periods, dispatch may occasionally take an extra day.

To avoid plants being held in depots over a weekend, we do not usually dispatch on Fridays. Highlands and Islands orders using a two day service are not normally dispatched on Thursdays.

Available basket sizes:

• 3 Litre Hexagonal Basket – 18 × 18 × 16cm

Planting depth is measured from the top of the aquatic basket to the water surface.

Finofil baskets are manufactured in the UK from 100% recycled plastic and are fully recyclable. Their fine dual-mesh construction helps retain aquatic soil while allowing water and nutrients to reach the roots. Basket shape may vary slightly depending on the plant and supplier availability.

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Similar pond plants

For another pond-edge planting option, compare Marsh Marigold (Caltha palustris) and Golden Club (Orontium aquaticum). Explore the Caltha pond plant group to compare the whole collection.

Explore more marginal pond plants or browse our complete pond plants range. Need baskets, aquatic soil or planting essentials? Browse our pond plant baskets and aquatic planting supplies.