About
Lagarosiphon major, curly waterweed, is a submerged, perennial aquatic with close-set, recurved, dark-green leaves and small, tubular, pinkish flowers in summer. Note: this plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive non-native species and is banned from sale. It must not be introduced into the wild.
About the genus
Lagarosiphon are semi-evergreen, submerged aquatic perennials forming branched stems clothed in spirally arranged, linear-lanceolate leaves and tiny, white or pink flowers in summer. Several species are highly invasive � check current legal restrictions before growing.
Growing conditions
SunlightFull sun
Soil typeLoam
Soil pHAcid, Alkaline, Neutral
Soil moisturePoorly-drained
AspectSouth-facing, East-facing, West-facing
ExposureExposed, Sheltered
UK hardinessH5
Plant details
Plant typeAquatic
HabitSubmerged
FoliageSemi evergreen
HeightUp to 10 cm
Spread0.5-1 metres
Time to full height5-10 years
Suggested usesPonds, water features, bog gardens.
Care notes
CultivationThis plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive non-native species. Across the EU, UK and NI it is an offence to plant or cause to grow in the wild plants listed on Schedule 9 of this order. These plants should not be planted or caused to grow in the wild and in addition are banned from sale. Gardeners possessing them should undertake measures to control them. See RHS advice on invasive non-native species for further information
PruningMinimal pruning required. Remove dead or damaged growth as needed.
PropagationSee cultivation notes
Pest resistanceGenerally trouble-free. Monitor for slugs and aphids.
Disease resistanceGenerally disease-resistant. Ensure good air circulation.