Aggressive Perennials in the Garden

Perennials you should not plant

By: Sandy Feather ©2008
Penn State Extension

Q. I am new to gardening, having started most of my perennial beds in the last three years. I have been disappointed in some of my perennial purchases since they have taken over my garden. I have been taken in by the quirky flowers and superb fall color of gooseneck loosestrife, the colorful foliage of chameleon plant, and the wonderful fragrance of mint. Is there a list of perennials one should avoid? I need a list of aggressive perennials to avoid before I shop at garden centers this spring!

A. There are perennials that are very aggressive in garden beds, as opposed to invasive species that quickly overrun natural areas. My answer is going to focus mainly on those perennials that can be aggressive in the garden, but which are not taking over Penn’s Woods at an alarming rate – at least not yet. How aggressively a plant behaves depends on soil texture, moisture, and sun exposure.

For example, Japanese anemones are lovely late summer bloomers that can be quite aggressive in the shade and good garden soil. They are meeker in full sun and clay soil. I think of these plants as garden bullies – plants that will push right over a neighboring plant without so much as a “pardon me.” The worst offenders spread aggressively by rhizomes (underground stems), often popping up alarmingly far from where they were originally planted.

Lamb’s Ear - Stachys byzantina
Lamb’s Ear (Stachys byzantina)

Many of these plants are pretty, attractive to butterflies and pollinators, tasty, fragrant, or otherwise useful in the garden. Although you may wish to avoid these plants altogether, be aware that these garden thugs can have uses, including holding an erosion-prone bank in place, even when it is composed of nothing but clay and shale. In some situations, you may find you need an aggressive plant. To quote Dr. Allan Armitage, “There is no such thing as a bad plant, only a bad use for a good plant.”


Bounded by Hardscape

As long as you are aware of their thuggish nature, you can make use of aggressive garden plants. They can be grown in areas bounded by hardscape – between a building and a sidewalk, for example, where they cannot escape. They can also be grown in containers so that you can enjoy their beauty, fragrance, or flavor, without spending a lifetime of weeding them out of areas where you do not want them growing. Be sure to keep the containers up off the ground so their vigorous roots do not sneak out of the drainage holes and establish themselves in the ground.

Bugleweed or Ajuga reptans
Bugleweed (Ajuga reptans)

Always be wary when you hear words like “vigorous,” or “fast growing ground cover” to describe a plant. Many plants with square stems, such as bee balm, belong to the mint family, and share its tendency to take over. Other members of the mint family such as oregano are much better behaved.
I’m sure there are many plants that could be added to this list, so use it as a starting point. It is also helpful to look up plants before you buy them and add them to your garden so you know what you are getting. A brief bibliography will follow the plant list.


Aggressive Garden Perennials

Lilileaf Lady Bells (Adenophora lilifloria)

Bishop’s Weed (Aegopodium podagraria)*

Bugleweed (Ajuga reptans)

Japanese Anemone (Anemone x hybrida)

Wormwood (Artemesia spp.) – especially A. ludoviciana ‘Silver King’ and A. vulgaris ‘Limelight’

Tartarian Aster (Aster tartaricus)

Clustered Bellflower (Campanula glomerata)

Lily-of-the-Valley (Convallaria majalis)

White Snakeroot (Eupatorium rugosum, now classified as Ageratina altissima)

Swamp Sunflower (Helianthus angustifolius)

Chameleon Plant (Houttuynia cordata 'Chameleon')

Yellow Archangel (Lamium galeobdolan)

Gooseneck Loosestrife (Lysimachia clethroides)

Creeping Jenny (Lysimachia nummularia)

Purple Loosestrife (Lythrum salicaria)* 
On Pennsylvania's Noxious Weed List

Plume Poppy (Macleaya cordata)

Mints  (Mentha spp.)

Bee Balm (Monarda didyma)

Showy Evening Primrose (Oenothera speciosa)

Ribbon Grass (Phalaris arundinacea)*

Obedient Plant (Physostegia virginiana)

Lamb’s Ear (Stachys byzantina)

*These plants are considered a threat to natural areas.


Herbaceous Perennial Plants, 3rd Edition, Allan M. Armitage, Stipes Publishing, 2008. ISBN 9781588747754.

Armitage’s Garden Perennials, Allan M. Armitage, Timber Press, 2000. ISBN 0881924350.

The Color Encyclopedia of Ornamental Grasses, Rick Darke, Timber Press, 1999. ISBN 0881924644.

The Well-Tended Perennial Garden, Tracy DiSabato-Aust, Timber Press, 2006. ISBN 0881928038.

Manual of Herbaceous Ornamental Plants, Steven M. Still, Stipes Publishing, 1994. ISBN0875634338.


Converting lawn to wildflowers

Photos of perennials (from A - M)

Photos of perennials (from N - Z)


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