Japanese Knotweed

The worst weeds in the world and Japanese knotweed and horsetail though fortunately they are not too widespread. Knotweed forms great strands of pinkish bamboo-like stems and broad oval leaves with loose sprays of white flowers to a height of 2.4 meters or more.

Horsetail is a prehistoric plant which emerges rather like an erect dull green bottle brush.

These weeds are so vigorous that you need a good deal of persistence to get rid of them. The roots go so deep that digging is no use at all and pulling the tops off is a life sentence.

If the invasion is not yet too serious chemicals should work - crush the leaves and stems when plants are growing strongly in summer and apply weed killer containing glyphosate. Several applications will probably be needed.

For serious infestations it's best to smother them out. Laying black polythene over the whole area will deprive them of light and eventually kill them off, though it might take up to two years to eliminate them completely.