Water parsnip (Sium floridanum) care guide

Group
Plants
Other names
Sium suave, Hemlock waterparsnip, Water parsnip, Sium cicutifolium
Family
Apiaceae (carrot family)
Origin
As Sium suave: North America, Russia and eastern Asia (China, Korea, Japan)
Water
freshwater
Maximum size
300 cm
Temperature
8–24°C
pH
6.5–8
Hardness
5–20 dGH
Care level
expert
Lighting
Medium to high light underwater; full sun to part shade emersed

Care

Sium floridanum is now treated as a synonym of Sium suave, the water parsnip, so that is the current name. It is a perennial wetland herb of marsh and pond margins, wet prairies, ditches and shallow water, which can reach about 3 m when flowering, with smooth stems, pinnate leaves and flat umbels of small white flowers in high summer. Young plants and submerged growth form a rosette of finely divided leaves that has occasionally been kept in aquaria, but our sources say nothing about aquarium use and it is really a large marginal plant. It is happiest in wet mud or standing water a few centimetres deep in a pond or bog garden. Water figures are our estimate, not from the sources. Caution: it closely resembles the highly poisonous water hemlocks, and its stems and leaves are toxic to livestock. Do not eat it, and label it clearly. It is a temperate plant that suits ponds and coldwater set-ups rather than tropical tanks. Sources: Wikipedia (en.wikipedia.org/wiki/Siumfloridanum); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Sow seed in late winter or early spring in a cold frame, on wet mucky soil or sand; seed ripens in September and October. Plants are self-fertile.

Compatibility and tank mates

A pond and bog-garden plant rather than an aquarium plant; poor in warm tropical tanks. Keep away from livestock and pets that might chew it.

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

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