Perennials are a favorite for many gardeners. They come back year after year, filling garden beds with color and life. Their varying bloom seasons add variety to your garden, making it interesting and appealing all through the season. However, some plants grow a little too well and, while they may be popular choices, these are perennials that can overrun your garden if left unchecked.
List of Perennials That Can Overrun Your Garden
The plants in this list are often valued for their ability to fill bare spaces fast, but that same trait can make them a nuisance. Learn more about why they spread so aggressively and what you can do to keep them in check.
1. Black-eyed Susan (Rudbeckia fulgida)
Black-eyed Susans are gorgeous perennials that produce cheerful yellow flowers over a long season from mid to late summer. They spread by seed and underground stems (rhizomes), forming dense colonies if left alone.
Containment tip: Remove spent flowers before they set seed. Then, dig up new shoots that pop up outside your desired area.
2. Mint (Mentha species)
Mint is prized for its scent and flavor, but it is notorious for taking over garden beds. It spreads by fast-growing runners above and below the soil.
Containment tip: If you want to grow mint, do it in pots or containers. If you decide on planting in the ground, sink barriers at least 12″ (30 cm) deep around the plant.
3. Gooseneck Lysimachia (Lysimachia clethroides)
This plant’s white, gooseneck-shaped flower clusters are beautiful, and they certainly make your garden look gorgeous. However, gooseneck lysimachia spreads aggressively by rhizomes and can crowd out its neighbors in just a few seasons.
Containment tip: Plant it in a contained area, such as a raised bed. Dig around the clump each spring to remove spreading roots.
4. Chameleon Plant (Houttuynia cordata)
The chameleon plant has colorful foliage and thrives in wet spots. This is one of those perennials that spreads rapidly by rhizomes, popping up several feet away from where it was planted.
Containment tip: The chameleon plant is best grown in containers or spaces restricted by pavement. You should also remove stray shoots quickly and never plant them near natural waterways.
5. Wintercreeper (Euonymus fortunei)
Wintercreeper is a hardy evergreen groundcover. It is a perennial that spreads by rooting at the nodes along its stems and can climb trees and structures.
Containment tip: Make sure you regularly edge around plantings. Also, you should prune aggressively to stop wintercreeper from climbing or escaping beds.
6. ‘Angelina’ Stonecrop (Sedum rupestre)
This low-growing succulent spreads by rooting stems. ‘Angelina’ stonecrop can quickly cover rock gardens and spill into lawns or other beds. In short, it can easily take over your garden, and you will not know where to start to mend it.
Containment tip: Remember to plant ‘Angelina’ stonecrop where you do not mind it wandering or edge beds to keep it in bounds. It’s easy to pull unwanted stems by hand when necessary. Keep in mind that small bits of plant material left behind can easily sprout to create more plants, so you’ll want to be thorough when cleaning up.
7. Common Milkweed (Asclepias syriaca)
Milkweed is great for monarchs and other pollinators, but it spreads by both deep rhizomes and seeds, colonizing large areas quickly.
Containment tip: Deadhead the flowers before seeds mature. Also, dig out unwanted shoots regularly. And plant these perennials in a spot where spreading is welcome, so you do not end up with loads of work on a single plant.
8. Shasta Daisy (Leucanthemum x superbum)
Shasta daisies are classic perennials. They spread by both seed and clumping roots, which can crowd out other plants.
Containment tip: Divide clumps every few years and remove self-sown seedlings.
9. Periwinkle, Vinca (Vinca minor)
Periwinkle is a popular groundcover, spreading by long, trailing stems that root wherever they touch the soil. Once established, it can quickly form dense mats that are difficult to remove.
Containment tip: Remember to regularly trim back runners. Moreover, you should create physical barriers or plant in contained areas to prevent escape.
10. English Violet (Viola odorata)
Sweetly scented violets spread by seed and above-ground runners, forming thick mats that will intrude on any part of the landscape from flower beds to turf grass.
Containment tip: To prevent these perennials from overrunning your garden, remove unwanted clumps and deadhead flowers to reduce self-seeding.
11. Bergamot, Bee Balm (Monarda hybrid)
Bee balm is a pollinator magnet. It spreads by rhizomes, creating large, dense patches over time.
Containment tip: Divide clumps every 2-3 years and dig out wandering shoots.
12. Plumbago (Ceratostigma plumbaginoides)
Plumbago is a plant that spreads by underground stems, making it a robust groundcover that can take over beds.
Containment tip: Keep it contained with edging, and remove stray shoots each season.
Tips for Managing Aggressive Perennials
There are a few tips that you should keep in mind when you have perennials that can overrun your garden.
- Always check how a plant spreads before adding it to your garden. You may want to try searching, “how does [insert plant name] spread”, to learn more about its behavior.
- Avoid planting perennials that are known to be fast-spreaders next to each other. They will quickly intermingle making them difficult to “untangle” later. They’ll also overrun surrounding plants twice as fast.
- Barriers such as deep garden edging or raised beds can help contain known spreaders.
- Confined spaces surrounded by pavement, such as between a curb and a sidewalk, are perfect places to grow and contain perennials that you love, but that may spread too aggressively.
- Containers are one of the most popular ways to grow your favorite herbs and perennials without worrying about them spreading throughout the garden.
- Perform regular maintenance, like deadheading, dividing, and digging up unwanted shoots to help keep these perennials in check.
Some aggressive perennials can be managed with a little planning and effort. When you know what to expect, you can easily ensure that your garden will always look amazing and your plants will always be healthy. So, enjoy the beauty and the benefits of perennials, but be ready to give them some boundaries!
Using Fast-spreading Perennials for Groundcover
Alternatively, some fast-spreading perennials can be an excellent solution for large areas where you need a dense groundcover. This can include spaces that are difficult to maintain such as rocky areas and slopes or areas that are prone to drought and difficult to water. Perennial plants are a way to add beauty while providing the benefits of soil erosion control.
Better yet, some perennial groundcover plants look good year-round. Learn more in our article, 12 Evergreen Groundcovers for a Low-Maintenance Landscape and see if there is an evergreen option that would be right for your location.
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