Here are a few garden aggressors you may want to think twice about before planting.
Physalis alkekengi are aggressive plants that you should warn fellow gardeners about. The lanterns are great for dried arrangements, but the plant spreads quickly via underground stems. And once you have this plant, you will spend years trying to eliminate it from the garden.
Achillea millefolium is a perennial that can be found listed in both weed and perennial books. This blooming beauty tolerates hot, dry conditions and readily reseeds and spreads. I spent years weeding this out of my backyard butterfly garden. Select less aggressive species and cultivars that do not reseed.
Phalaris arundinaceae picta is another vigorous grower. This 3-foot-tall cream-and-green striped grass spreads by rhizomes. Once it takes hold, it will weave itself throughout the garden, crowding out any weaker perennials.
Giant silver banner grass
Miscanthus sacchariflorus robusta is another aggressive ornamental grass. This 5- to 6-foot-tall grass can quickly fill a garden, swale or any area where it is planted. They fill space fast and will quickly encroach on the rest of your landscape, as well as your neighbour’s.
Lysimachia nummularia is a ground-hugger that tolerates sun and shade as well as wet soils. Yellow flowers resembling buttercups top the coin-shaped green leaves in late spring. The yellow cultivar Aurea is a bit less aggressive than the species. Avoid using moneywort near natural waterways, and be prepared to do a bit of weeding to control it.
Lysimachia clethroides, a close relative to moneywort, is another garden bully. The slender white spiky flowers are curved, hence their name. If you plant this in your garden, be prepared to lift and divide yearly to keep it in check.
Also known as bugleweed is a popular ground cover recommended for shady locations. This vigorous grower has tried to creep into my sunnier areas, infiltrating the lawn and surrounding perennials. Consider less aggressive cultivars, or use a physical edge, walk or other barrier to keep this eager grower contained.
Physostegia virginiana does not behave as its name suggests it would. This rapidly spreading plant is 2 to 4 feet tall and blooms in late summer and fall. Plant this in your perennial garden only if you can keep it in bounds.
Also beware of bargain backyard plant sales. These are often filled with aggressive plants that have overrun the seller’s garden. Keep a keen eye out for these, and your yard won’t have to contend with garden bullies.