Invasive non-native plants in your garden: how to recognise and replace them
Some popular garden plants spread into the wild and crowd out the native plants there. How to recognise them, and some good alternatives.
A non-native (or exotic) plant is one that doesn’t occur naturally in our part of the world. Most non-natives are harmless. But some spread from gardens into the wild, grow faster there than the native plants and crowd them out. These are invasive non-natives.
The best-known ones in our gardens
- Cherry laurel: a popular evergreen hedge. Blackbirds and thrushes eat the berries and so sow cherry laurel in woodland, where it forms a dense, dark shrub layer.
- Black cherry (American black cherry): once planted in woods on sandy soil, now one of the most troublesome invaders in the Campine (Kempen) region of northern Belgium and on the Veluwe in the Netherlands.
- Tree of heaven: grows at a tremendous rate, throws up masses of root suckers and is on the EU list of invasive species.
- False acacia (robinia): enriches poor, sandy soil with nitrogen, so that the typical vegetation of heathland and dunes disappears.
- Japanese rose (Rosa rugosa): a sturdy hedge, but on the coast it crowds out the dune plants.
- ShrubCherry laurelPrunus laurocerasus
- Broadleaf treeBlack cherryPrunus serotina
- Broadleaf treeTree of heavenAilanthus altissima
- Broadleaf treeFalse acaciaRobinia pseudoacacia
- ShrubJapanese roseRosa rugosa
Good to know
Japanese knotweed is another notorious example: a plant with hollow, bamboo-like stems that can even grow through tarmac. It isn’t in our own guide, but you’ll find it under Species if you search for ‘duizendknoop’ (its Dutch name) or ‘Reynoutria’ (its scientific name).
Good alternatives
| Instead of | Choose |
|---|---|
| Cherry laurel | yew, holly, privet, laurustinus |
| Black cherry | native bird cherry, rowan, alder buckthorn |
| Tree of heaven | large-leaved lime, hornbeam, whitebeam |
| Japanese rose (on the coast) | dog rose, sea buckthorn |
Removing them
- Pull up seedlings, roots and all, when the soil is moist.
- Saw down a large shrub and dig out the root stump. If the roots stay in the ground, it often sprouts again.
- With tree of heaven and black cherry, felling alone just produces masses of new shoots. For large trees, ask a tree surgeon for advice.
- Prunings with berries or roots should never be dumped in the countryside: take them to the recycling centre (containerpark) or put them in your garden waste bin.
Tip
On every species page, the Pruning section shows the label Invasive non-native, and the planting advice (Will it fit here?) warns you if you’re about to plant one.