Helensburgh and Lomond Japanese Knotweed hotspots revealed

The plant, known for its fast and aggressive growth, is in its peak flowering season from late summer through August and early September.

Growing up to three metres tall with roots reaching down 20 metres, the plant is known for wreaking havoc on homeowners, destroying pipework, drains and even weakening building foundations.

Heart shaped leaves from Japanese Knotweed (Image: Japanese Knotweed Specialists)

Helensburgh has been identified as Argyll and Bute's hotspot for Japanese Knotweed, closely followed by the Isle of Bute.

The figures have remained almost the same since we previously reported on the hotspot areas in Helensburgh and Lomond in March.

According to research by invasive plant specialists Environet, there are 45 recorded occurrences of Japanese knotweed within a four-kilometre radius of Helensburgh town centre itself.

The A818 between the town and Arden also has a high concentration of the plant, with 39 cases within 4km of the town and another 26 within a 4km zone around Arden.

There are 39 cases within 4km of Rhu and Shandon, and 27 within 4km of Garelochhead.

Many of these cases, however, will be duplicates, as the 'within 4km of Helensburgh' zone, for example, overlaps with 'within 4km of Rhu'.

If Japanese knotweed is found on private property, the law states that the land owner must take the necessary steps to prevent any further growth.

The plant has cream coloured flowers (Image: Japanese Knotweed Specialists)

Some parts of Glasgow have recorded 138 sightings of the plant within 4km. While in London, some parts have recorded 265 sightings of knotweed.

While it hibernates over winter, from March and April it returns and can destroy pipework, drains and can even weaken building foundations.

You can check their full list of hotspots here.

According to experts Japanese Knotweed Specialists, now is the time to act.

A spokesperson said: "Japanese Knotweed is most visible and active during the flowering season. If not controlled, it can quickly take over gardens and cause long-term damage due to its aggressive nature and strong desire to reproduce."

They said three critical indicators of Japanese Knotweed to look out for in the summer months are:

White to cream-coloured flowers

The flowers grow in clusters, known as panicles, which can be 6 to 15 cm long and feathery in appearance.

Heart-shaped leaves

The leaves are broad and heart-shaped, with a pointed tip. They range from 7 to 14 cm long and often grow in an alternate pattern along the stem.

Hollow, bamboo-like stems

The plant's hollow stems, similar to bamboo's, can be green, red, or purple. It has a zigzag growth pattern and can reach 3 to 4 metres (10 to 13 feet). It can form dense thickets that are difficult to control and penetrate.

To find out more, visit japaneseknotweedspecialists.com.