Invasive garden plants

weed hoeingMost gardeners will have heard about Japanese knotweed, the problems it causes and how difficult it is to eradicate. More than 100 years ago it was sold and grown as a garden plant, but thoughtless dumping of plants in the wild led to its escape. Unfortunately it is not the only plant to have escaped and to have caused a problem in the British countryside.

Our botanists are working on some of these garden plants to establish the nature of this problem, as the situation is nowhere near as straightforward as often assumed. A more accurate understanding will allow more effective use of resources to tackle the real invasive non-native species.

Invaders that threaten our native plants

It is said that a weed in the garden is a just plant in the wrong place, but what about the unwelcome plants that thrive and spread outside our gardens? Many are not really weeds, but have been planted by gardeners in the past, unaware of their invasiveness.

Some of the most troublesome weeds include non-native water primrose (Ludwigia species) and giant hogweed (Heracleum mantegazzianum).

Read RHS advice about controlling weeds

Watch a video interview with Dr Ken Thompson and plantsman James Wong on invasive plant species to the UK

Watch a John MacLeod lecture video which covers invasive plant species to the UK, and is given by Dr Ken Thompson


With your support, we can undertake valuable research into gardening pests and diseases.

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.