Marsh-marigold (Caltha palustris) care guide

Group
Plants
Other names
Kingcup, Molly-blob, Water boots, Cowslip (North America), Caltha palustris 'Flore Pleno'
Family
Ranunculaceae (buttercup family)
Origin
Temperate Northern Hemisphere, including Britain
Water
freshwater
Maximum size
80 cm
Temperature
0–22°C
pH
5.5–7.5
Hardness
Tolerant (estimate)
Care level
expert
Lighting
Full sun to part shade, emersed

Care

Warning: this is a bog and pond-margin plant, not a true aquarium plant. Kept fully underwater it slowly weakens and dies, so grow it emersed in a paludarium, bog garden or pond margin, with only its roots and crown in shallow water. Marsh-marigold or kingcup (family Ranunculaceae) is a perennial of marshes, fens, ditches and wet woodland across the temperate Northern Hemisphere, including Britain. It grows among reeds at lake and river edges, likes oxygen-rich water near the soil surface and rich soil, but dislikes fertiliser, high phosphate and ammonium, and brackish water. It grows 10–80 cm tall, with kidney-shaped leaves and glossy yellow flowers 2–5.5 cm across from spring to summer. It dies back in autumn and overwinters as buds at the soil surface. The double 'Flore Pleno' holds the RHS Award of Garden Merit. It is one of the best native plants for a wildlife pond edge or bog garden. It contains protoanemonin, which is toxic if eaten raw, and the sap can blister skin. Water figures are our estimate, not from the sources. It is a cold-hardy pond plant and unsuitable for tropical tanks. Sources: Wikipedia (en.wikipedia.org/wiki/Calthapalustris); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Divide clumps after flowering. Seed is produced only by cross-pollination; it floats and germinates on wet mud.

Compatibility and tank mates

Do not sell or buy it as a true aquarium plant; it belongs in a paludarium, bog garden or damp border. In a pond, fish leave it alone.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

About Aquatic-Auctions

  • Aquatic-Auctions (aquatic-auctions.com) is a UK online marketplace for aquarium and pond livestock and equipment: tropical and marine fish, corals, shrimp, snails and other invertebrates, aquatic plants, tanks, filtration, lighting and food.
  • Items are sold by auction, buy it now or classified advert, by hobbyist and business sellers in the UK.
  • Buyers pay sellers directly; Aquatic-Auctions does not hold the money. Hobbyist sellers must offer PayPal and may also take cash on collection. Business sellers take PayPal (required) or cash on collection, and bank transfer only once they have a seller rating of 50 out of 100, a company and pet-selling licence checked by Aquatic-Auctions, a bank account in the company's name, and bank details approved by Aquatic-Auctions.
  • Buyers are told to pay by PayPal Goods & Services, never PayPal Friends and Family, gift cards or crypto.
  • Live fish and other vertebrates must be sent by specialist live-animal couriers (for example APC Overnight or DX Express), never by Royal Mail. Some invertebrates and plants may go by Royal Mail Special Delivery or 1st Class within its rules.
  • Banned and invasive species (for example those on the GB invasive species lists) cannot be listed, and sellers must meet the site’s animal welfare standards.
  • Members must be 16 or over to buy (16 and 17-year-olds with a parent or guardian’s agreement); sellers must be 18 or over.
  • Business sellers show their address, company details and pet-selling licence to buyers. Seller ratings run from 0 to 100: +1 for each positive feedback, −1 for each negative.
  • The site includes a free community species wiki with care guides (water parameters, tank size, diet, temperament, breeding).
  • Aquatic-Auctions is run by Etavonni Tech Limited trading as Aquatic-Auctions (company number 10204188), Aldershot, Hampshire, UK. Contact: info@aquatic-auctions.com.