Could You Identify Japanese Knotweed in Your Garden?

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How to Tell Between Different Types of Knotweed in UK

You need to look out for the key features in order to identify different types of Japanese knotweed. You can easily identify this weed throughout different seasons.

Here at JKSL, we specialise in Japanese knotweed identification, there are various types of knotweed in the UK, including:

Combining more than 15 years of experience with cutting edge capabilities:

Japanese Knotweed (Fallopia japonica)

Japanese knotweed is the most widespread and known species of knotweed. There is a distinctive growth pattern of one stem per node, which creates a zigzag design. The leaves are mid-green in colour, fairly smooth and have truncate leaf bases; often compared to a shovel/spade shape. The plant produces loose clusters or panicles, made of tiny, creamy-white flowers, which appear late summer / early autumn.

Giant Knotweed (Fallopia sachalinensis)

The leaves of Giant knotweed are much larger and elongated than those of Japanese knotweed. They have heart shaped bases (cordate) and are pointed at the tip. It also grows much taller, 4 to 5m in a single season.  The plant bears dense clusters of small green-white flowers in late summer/early autumn. It is widespread across the UK but much less common than Japanese knotweed.

Hybrid Knotweed (Fallopia x bohemica)

This is a hybrid species between the Giant knotweed and the Japanese knotweed. This weed is less common than Japanese knotweed in the UK and varies in habits. The darker-green leaves are broadly ovate with a pointed tip and rounded base. The veins are reddish purple. The creamy-white flowers are a dense cluster.

Dwarf Japanese Knotweed (Fallopia japonica var. Compacta)

This plant, also called Polygonum reynoutria, is a dwarf type of the Japanese knotweed. It reaches up to 40 inches in height. It has the traditional zigzag structure of the petiole but the leaves have crinkled edges that are darker green. It produces a leathery texture with reddish veins that are curled into a concave shape. Flowers are clustered and come in pale pink or white colours. The weed is less invasive than the Japanese knotweed.

Himalayan Knotweed (Persicaria wallichii)

This knotweed is known by many names. It has slender with elongated leaves and resembles Giant knotweed and Lesser knotweed. It originates from the Himalayas from South West China to Afghanistan. It is not very common in the UK but is more prevalent in South West England. It can reach up to 1.8 meters high.

The green stems are hairy with a brown sheath at the base of the leaf stalk. Leaves are dark green, leathery, long and slender with a slightly heart-shaped base. Flowers are pale pink or white and bloom in summer or late autumn. They are common in riparian areas where they can survive infrequent flooding.

Lesser Knotweed (Persicaria campanulate)

This is also called the Reynoutria or Polygonum campanulata. The weed originated in North India and southwest of China. Although it grows with the same vigour as the other knotweeds, it is less invasive. The leaves come in varied sizes but retain the same growth speed and long shape. It resembles the Himalayan Balsam.

It grows better in moist soil. The veins can be reddish in colour with a herring-bone shape. The inner side of the leaves is felted by small white hairs and is lighter in colour. The zigzag is distinctively absent. The weed is more common in Northern Ireland and Scotland.

Selling a property is hard enough, but a slight trace of Japanese knotweed can deter a buyer. Some banks are questioning mortgage opportunities at the hint of Japanese knotweed presence. This is due to the speed and ferocity that knotweed grows. There are several methods Japanese knotweed experts use to get rid of the weed. These methods will be determined by the scale and the magnitude of the spread.

It is important to seek Japanese knotweed services as soon as you suspect the invasive weed. Please contact us if you think you have Japanese Knotweed and we can advise on the best treatment methods for your site.

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