THE top Japanese knotweed hotspots in Hampshire have been revealed in a new map. 

Infestations of the invasive plant can mean trouble, with it known to severely damage properties.

It usually emerges in March or April and can reach up to 2.5 metres in height by the time summer rolls around.

Environet, an invasive plant specialist, has revealed this year’s hotspots for the plant following the latest data from its live online tracker.

Basingstoke Gazette: Japanese knotweed hotspots in Hampshire in 2023Japanese knotweed hotspots in Hampshire in 2023 (Image: Environet)

Full list

  • Southampton comes out on top in Hampshire, with 118 infestations reported in 2023.
  • This is a stark contrast between runner-up Portsmouth, which only had 30 infestations.
  • Aldershot and Winchester had 29 infestations respectively and Andover had 24.

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Protect your property

Nic Seal, founder of Environet, said: “Vigilance is the best way to protect your property from the risks posed by Japanese knotweed.

“Make sure you know what knotweed looks like and how it differs from other common garden weeds like ivy and bindweed, so you can keep an eye out for it in your garden and neighbourhood.

“Knotweed is easily identifiable during summer, but as we head through the autumn and into winter, the above-ground growth dies back, and it becomes much harder to spot.

“It’s also easier to conceal, so anyone viewing a property to buy should be extra careful.”

Japanese knotweed is identifiable by its hard, bamboo-like canes and distinctive shield-shaped bright green leaves which grow in a zigzag pattern along the stem.

Mature plants flower in August, becoming covered in clusters of white flowers.

Knotweed does not produce viable seeds as all the plants in the UK are female.

It is usually spread accidentally through the movement of soil or gardening waste, or via rivers and streams when pieces of rhizome break off and take hold in new locations.