Some of the most attractive and useful garden plants can also be the most invasive. Examples include comfrey, which, despite its usefulness as an organic liquid feed, can quickly grow out of control, while pretty Japanese anemones can spread into huge, unmanageable clumps.
Sadly, despite their beauty, invasive plants out-compete others in the garden. Some also escape into the wild, where they grow alongside, and often kill, native plants, which can disrupt the ecosystem.
Luckily, there are some cultivars or closely related versions of invasive plants that aren’t problematic to grow. It may be that they’ve been bred to flower without producing pollen, therefore they can’t spread as readily as the species. Or they might be the product of a hybridisation, resulting in a less vigorous growth habit.
We’ve picked out some of our favourite cultivars of invasive plants, that are safe to grow. Find out more, below.
Cotoneaster frigidus ‘Cornubia’
Cotoneasters are popular garden shrubs and come in a range of forms and varieties. Some species are highly invasive and are listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales. The popular garden variety Cotoneaster horizontalis is on the list, making it an offence to plant or otherwise cause to grow these species in the wild (this includes allowing it to spread out of your garden). It’s therefore advisable to choose an alternative.
Cotoneaster frigidus ‘Cornubia’ is one of the largest cotoneasters, usually forming an enormous bushy shrub. It bears flat flowerheads in summer, followed by large red berries. But the best thing about it is that it’s not invasive. The Royal Horticultural Society has assigned it the Award of Garden Merit (AGM).
Anemone ‘Wild Swan’
Japanese anemones can be invasive. Spreading by underground runners, they can quickly become out of control, and are difficult to eradicate. They tend to be most invasive in loose, sandy soils, where they can spread more easily.
Anemone ‘Wild Swan’ is a delicate, white-flowering cultivar, thought to be a cross between early and late flowering species (possibly Anemone rupicola and Anemone hupehensis). Far less invasive than Anemone hupehensis, Anemone hupehensis var. japonica and Anemone × hybrida, ‘Wild Swan’ is a much better option for those with sandy soils or in need of a low-maintenance garden.
Comfrey ‘Bocking 14’
Comfrey has a reputation for being invasive. In fact, there are many types of comfrey and not all of them are as troublesome as Russian comfrey, Symphytum x uplandicum, which was identified by Henry Doubleday as being a fantastic plant for use in the kitchen garden. However, it spreads like wildfire.
In the 1950s, Lawrence Hills continued Doubleday’s research and developed a comfrey research program in the village of Bocking, in Essex. He tested more than 20 comfrey strains, each one named after the village. Strain 14 came out top in tests for its nutritional content but also as the least likely to spread, as it didn’t produce seeds. It’s the best choice for organic gardeners who want a reliable source of plant food without risk of it taking over the plot.
Running bamboos bear long underground stems, or rhizomes, and are considered invasive because, if not managed properly, they can quickly take over the garden. They can be almost impossible to eradicate.
Phyllostachys nigra is a running bamboo but its growth habit is far less vigorous than others in the Phyllostachys genus. It has attractive green culms which darken to black/brown with maturity, and a graceful, arching habit.
Greater periwinkle bears pretty purple flowers over dark green foliage. It’s best for large gardens, or areas where it can spread without control, but it can be invasive. Lesser periwinkle is far less invasive than greater periwinkle, and is ideal for small gardens. It bears pretty, pale blue-purple flowers from April to September.