Gorgeous plants are usually the perfect additions to gardens – but some of the most attractive varieties can become surprisingly difficult to manage once they are established. Many of these are designed to grow vigorously – and, in the right conditions, that can quickly become a problem.
'A plant that gives you stunning flowers or creates fast coverage can also spread beyond its space, overwhelm other plants, damage structures or become incredibly difficult to remove once it's established,' explains Dr Russell Sharp, gardening expert and founder of Eutrema.
From fast-spreading mint to towering Leyland cypress, these are five plants to think carefully about before allowing them to establish in your garden.
1. Mint planted directly into flower beds
Mint is one of the easiest herbs to grow. As well as boasting a wonderfully fresh fragrance, it has an abundance of practical uses in the kitchen.
Why it can become a problem:
The same vigorous growth that makes mint so easy to grow can also make it difficult to control.
'Mint spreads through underground roots known as runners, allowing it to move away from its original planting position and appear elsewhere in flower beds,' says Dr Russell. 'Once established, these roots can compete with other plants for space, water and nutrients.'
What to do:
You don't need to remove mint from your garden completely, but it is much better grown in a pot or container so its roots are contained. 'If mint has already escaped into a flower bed, remove as much of the root system as possible rather than simply cutting back the foliage,' adds Dr Russell. From here, any remaining roots can allow it to return.
2. Bamboo planted without checking the variety
Known for its modern, tropical appearance and ability to create privacy quickly, bamboo's tall stems and dense foliage can quickly transform a space.
Why it can become a problem:
Not all bamboo behaves in the same way, which is why checking the variety before planting is so important.
'Some types spread aggressively through underground stems called rhizomes, which can travel surprisingly far from the original plant, such as in lawns, flower beds, and even the gardens of neighbours,' says Dr Russell.
'Golden’ and ‘black’ bamboos are particularly attractive, but can develop a rapidly expanding rhizome system within a few years.
What to do:
Before buying bamboo, check whether you are choosing a clumping variety, which tends to grow in a much more controlled way. 'If spreading bamboo is already established, cutting back the visible stems won't solve the problem because the underground root system will continue producing new shoots,' he adds.
3. Ivy left to grow unchecked
A great choice for charming cottage gardens, ivy's green foliage can quickly cover anything it finds itself upon. It can also provide valuable shelter for wildlife.
Why it can become a problem:
The issue with ivy is not necessarily the plant itself, but allowing it to grow unchecked. 'It can spread across the ground, smother smaller plants and work its way into cracks and gaps in walls and structures,' explains Dr Russell. Mature ivy can also become heavy, particularly when it has been allowed to grow over the same surface for many years.
What to do:
Ivy can still have a place in the garden, but regular pruning is important to keep it within its intended area.
'Its leaves have a waxy coating that can make them difficult to treat effectively with weed treatments,' says Dr Russell. 'Specialist products such as ivy pre-spray can help open up this protective layer before applying a suitable herbicide.'
4. Leyland cypress planted too close to boundaries
If you're looking to create privacy quickly, Leyland cypress is excellent for this as it grows rapidly and produces dense foliage.
Why it can become a problem:
The speed of growth that makes Leyland cypress appealing is also what can make it difficult to manage.
'If left unchecked, these trees can become extremely large, blocking sunlight and taking up substantial amounts of space,' says Dr Russell. 'Branches or roots can also extend beyond property boundaries, potentially causing problems with neighbours.'
What to do:
Be sure to think about the mature size of the tree before planting it, rather than simply considering how much space the young plant takes up.
'If privacy is the priority, slower-growing hedging plants can be a more manageable long-term choice, particularly in smaller gardens,' adds Dr Russell. If you already have Leyland cypress, regular trimming is essential to keep it under control.
5. Ground elder
This can initially appear to be a useful ground cover plant, with it seeming like an easy way to fill bare patches of soil thanks to its fast-spreading green leaves.
Why it can become a problem:
Its ability to spread is exactly what makes ground elder such a frustrating plant for gardeners. 'It spreads through underground roots that can travel through borders, while even small pieces of root left behind can produce new growth,' explains Dr Russell.
What to do:
The best approach is to remove as much of the root system as possible rather than relying on cutting back the foliage.
'This can take time, particularly where ground elder has spread through an established border, and repeated removal may be necessary to prevent it returning,' he adds. If you want ground cover in your garden, choose intentional varieties that are suited to the space, such as hardy geraniums and alpine strawberries.
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