This is the time of year when duckweed and green algae blanketweed may begin to reappear.

Duckweed:

• Has a 3 lobed leaf with a thread thin root
• It could have seeded down last Autumn and will rise up now
• Use a dipping net as soon as any piece appears
• Or it will soon cover the entire water area.
• It is a British Native plant so is not banned but is troublesome if allowed to grow excessively

Blanketweed is a green algae growth:

• This looks like green cottonwool or can be like green froth
• It will start to grow quickly in the warm weather of late Spring especially if you had large volumes of frog spawn jelly decomposing into the water this month.
• This is a pond plant that can and will grow in any nutrient high water.
• It spreads by air in microscopic spores
• The Barleystraw product added in February/March should be having an inhibitor effect by now on this green algae growth.
• Newly hatched tadpoles will eat small amounts of blanketweed
• The rest should be overcome by waterlilies and other surface cover plants in height of summer
• But you need sufficient to cover 50% of water surface in summer for balance
• Do not twist the blanketweed around a stick to remove it from the pond as that traps young wildlife inside the twist
• Even leaving it in a pile on the pond side will not allow the creatures to get out.
• Unravel it and shake it over the water straight away to dislodge the trapped creatures.

Both duckweed and blanketweed are a nuisance & can be invasive. But they are not banned like other imported Non British Native invasive plants.

Watch out for other invasive pond plants -

• Since 2014 there have been 8 aquatic plants banned from sale in the UK
• Deal with all these carefully if you already have them in your pond.
• Do not throw into open waterways.
• Compost with care or better still put into a green waste bin for collection and future disposal by professionals.

See our Tips and Advice page for images for identification: Banned invasive pond plants and our article on duckweed found here.