The first signs of Japanese knotweed have appeared in North Devon, a month earlier than expected.

The warmest February on record has prompted the emergence of the invasive plant by removal firm Environet UK last week in Lee Bay.

Japanese knotweed hibernates during the winter months before emerging when the ground temperature reaches around 4°C, usually in late March or early April.

Red or purple asparagus-like shoots sprout from the ground and quickly turn into green bamboo-like stems, growing at a rapid rate to reach approximately three metres in height by June.

But the unseasonably warm weather has prompted knotweed to awake early from its winter slumber and begin its annual assault on property foundations, patios, driveways, cavity walls and drains.

Japanese knotweed growing in February in Lee Bay, North Devon. Credit: Environet UKJapanese knotweed growing in February in Lee Bay, North Devon. Credit: Environet UK

Environmental scientist Nic Seal, founder and MD of Environet, said: “In 20 years of operation, I’ve never seen Japanese knotweed appear in February.

“The unseasonably warm weather has awakened the plant from its winter hibernation and prompted it to start growing an entire month earlier than normal.

“We’re gearing up for an early start to our treatment season to give our customers maximum protection from this highly invasive plant.

“Those who discover knotweed on their land should seek professional advice.

“They will probably need to put a professional treatment plan in place to protect their property and themselves from the threat of litigation from their neighbours.”

While herbicide treatments require the plant to be in full leaf, it isn’t necessary to wait as it can be removed at any time of year.

Those who spot the plant can report the sighting on Environet’s new Japanese knotweed heatmap, Exposed.

Members of the public can enter a postcode to discover the number of reported knotweed sightings nearby, with hotspots clearly visible in yellow or red.

Environet also offers a free Japanese knotweed identification service. Just email a photo to