1L Powdery Alligator-flag Thalia dealbata

Code: PL0870
1L Powdery Alligator-flag Thalia dealbata
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1L Powdery Alligator-flag Thalia dealbata
Powdery Alligator-flag Thalia dealbata - 1L Pot

The Thalia dealbata is an aquatic plant that can grow up to 6ft in height. A panicle above the foliage supports its small violet flowers, and its blue-green leaves have attractive purple edges. It is a truly dramatic plant that will add height and colour to your pond. This plant is half-hardy but it should grow without any trouble in the southern regions of England. In colder parts of the UK it might lose its foliage during winter, although it can be overwintered in a greenhouse.


  • Flower Colour: purple in summer
  • Foliage Colour: green and grey/silver all year
  • Approx. Growth Height: up to 1.5m - 2.5m
  • Max. Spread: 0.5m - 1m
  • Flowering Time: summer
  • Planting Time: spring
  • Uses: in ponds, pond margins, bog gardens
  • Growing Habit: clump forming
  • Exposure: sheltered
  • Hardiness: half-hardy (may lose foliage in colder parts of the UK during winter)
  • Rate of Growth: max. height in 5-10 years


  • Light Requirements: full sun
  • Soil Requirements: clay, loamy, chalky, sandy, acid, alkaline, neutral
  • Moisture: poorly drained


  • Planting Depth: up to 15cm
Grow as a marginal aquatic in pond margins with a water depth of up to 15cm. Choose a sunny spot. In colder areas of the UK it will become deciduous although it can be over wintered in a greenhouse to provide some protection top the plant. It is suitable for zones 1 & 2 of a pond. Aquatic and marginal plants should be placed in pond plant baskets filled with aquatic soil (sold separately) and topped with a thin layer of gravel to help prevent the soil from washing away.

Caring and Maintenance

If you live outside of the south of England it may be too cold in your garden to leave this plant outside all year around. It could lose some foliage and become deciduous. If there is a particularly sudden and cold winter snap then it is advisable to move the plant into a greenhouse until the frosts have passed. Propagate by division in spring.

Below is a comparison of pot sizes. From left to right: 9cm Pot, 1L Pot, 3L Pot


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