Lagarosiphon major

curly waterweed

This plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive, non-native species and is banned from sale. See cultivation notes for further details A submerged perennial with close-set, recurved, dark green leaves and small tubular pinkish flowers in summer

Other common names

curly water thyme
giant water thyme

Synonyms

Elodea crispa

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Ultimate height

Up to 10cm

Time to ultimate height

5–10 years

Ultimate spread

0.5–1 metres

Loam

Moisture

Poorly–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

South–facing or East–facing or West–facing

Exposure

Exposed or Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Hydrocharitaceae
Native to GB / Ireland: No
Foliage: Semi evergreen
Habit: Submerged
Genus: Lagarosiphon are semi-evergreen, submerged aquatic perennials forming a cluster of branched stems clothed in spirally arranged, linear-lanceolate leaves, and tiny white or pink flowers in summer
Name status: Correct

How to grow

Cultivation

This 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

Propagation

See cultivation notes

Suggested planting locations and garden types

Get involved

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