Gardening expert reveals five danger signs you have Japanese knotweeds, and the hefty fine you could get from it

GARDENING experts have revealed the five danger signs you need to be on the lookout for to spot Japanese knotweeds.

The fast-growing weeds tend to shoot up around early May, so it’s the perfect time to start hunting for them.

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Gardening expert Chris Bonnett from GardeningExpress revealed the five danger signs you need to look out for.

The World Conservation Union claims the weed is one of the world’s worst invasive species, the weed’s root system and rapid growth of 10cm (four inches) a day can damage concrete foundations, buildings, roads and paving.

If you ignore official orders to remove Japanese knotweeds from your garden, you can face a hefty fine of up to £2,500.

He told Birmingham Live that the first sign to look for is red shoots coming out of the soil.

These can look a bit like asparagus spears and the leaves are normally rolled up and dark green or red in colour.

As the leaves mature, keep an eye out for heart-shaped leaves.

They’ll become a vibrant green colour and heart/shovel-shaped with a point at the tip.

The gardening pro added that some can be as big as 20cm across and they grow staggered at the stem.

Later in the summer, the plants will grow white or cream clusters of flowers

The flower clusters grow to approximately 0.5cm wide and 10cm long.

The heart-shaped leaves will still be visible along with the flowers, creating dense foliage.

If you spot bamboo-like stems then it might be another sign you have Japanese knotweeds.

The gardening whizz added that the stems are hollow with nodes – knobble points where the buds, leaves and branches come out.

The stems will have a zigzag pattern and can grow up to three metres tall and become brittle during the winter months.

Finally, be on the lookout for the horizontal creeping roots – known as rhizomes which are the underground part of the weed.

The outside is dark brown in colour and the inside will look orange or dark yellow.

If you spot the weed in your garden, you need to take action as it can damage the foundation of your property.

Government advice says you must stop Japanese knotweed from spreading beyond your property into the countryside.

Legally, you do not have to remove knotweed from your land unless it’s causing a nuisance but you can be prosecuted for letting it spread into the wild.