Some plants, while beautiful and ornamental, are also vigorous and thuggish, with a tendency to take over.
Thuggish plants are those that can overwhelm and push out other plants, some do this by being prolific self-seeders, while others send out fast-growing suckers that spring up and push aside other plants.
This is why it's always a good idea to do a bit of research around the plants you're thinking of buying before you make the purchase – many will prove tricky to get rid of if you decide you no longer want them in the garden.
While the plants in our list might be vigorous, you don't necessarily have to avoid them. Many can be grown in containers and plant breeders are always producing new, often less vigorous cultivars that are better suited to gardens. A bit of research around specific cultivars should reveal these traits.
Check out some of the most thuggish garden plants, with tips on how to control their spread.
Flag irises, Iris pseudacorus, is a native aquatic iris and a brilliant wildlife plant, but in small ponds and bog gardens it can quickly spread and overwhelm other plants. If you're worried about it spreading, try one of the less vigorous cultivars like 'Variegata'.
Borage (Borago officinalis) is a prolific self-seeder, as is the similar looking green alkanet (Pentaglossis sempervirens). Bees and other pollinators love the flowers, but they can swamp out other plants. Pull up unwanted seedlings. Older plants can be dug out, but make sure you remove all of the roots. Do leave some for pollinators, though.
Ajugas are often grown as ground cover plants for shade, but they can often do their job a bit too well. However, the spreading runners are easy to pull up and cut back to the desired size. Evergreen and great for pollinators, so still worth growing in the garden.
Rhus typhina is a small deciduous tree, prone to producing suckers that can spring up in borders and other unwanted places. In lawns they can be mown off, otherwise prune them out, or grow the plant in a large container. 'Tiger Eyes' is a less vigorous, dwarf alternative.
Like ajugas, lily-of-the-valley is often grown as a ground cover plant in shady spots. However, when conditions suit, they can run rampant. If you do find them thriving a little too much, grow in containers or try one of the less vigorous varieties like 'Albostriata'.
Persicarias, particularly Persicaria capitata and Persicaria amplexicaulis do like to spread themselves about. There are lots of lovely cultivars to grow, like 'Orange Field', but do give them plenty of space.
Welsh poppies, Papaver cambricum, have terrific self-seeding abilities, but it does mean that the seedlings can pop up all over the place, potentially outcompeting other plants. Control their spread by removing seedheads before they mature.
Phygelius varieties like 'African Queen' and 'Devil's Tear's' can really run riot if they find conditions to their liking, sending out spreading runners. Try growing them in containers for pops of colour, or plant in the ground but cut out any unwanted runners.
In the right growing conditions, Japanese anemones will spread rapidly and can be difficult to control. If they start spreading too far, dig up the unwanted parts of the plant, getting as much of the roots as possible. Or try less vigorous cultivars like 'Pamina' and 'Honorine Jobert'.
Euphorbia griffithii, including its cultivars like 'Fireglow' and 'Dixter', spread by means of underground runners, so you'll need to be prepared to restrict the size of the plants. Alternatively, go for one of the many other lovely euphorbias.
Houttuynia cordata can quickly spread in wet soils, forming dense colonies. It will grow in drier soils, though not as quickly, so can be restricted in this way, or you could grow it in a pot.