Biennial Wormwood: What Every Gardener Should Know About This Widespread Plant
If you’ve ever noticed a somewhat scraggly plant with silvery-green leaves popping up in disturbed areas, parking lots, or along roadsides, you might have encountered biennial wormwood (Artemisia biennis). This member of the Artemisia family has quite the story to tell – and it’s probably not what you’d expect from a wormwood.
What Exactly Is Biennial Wormwood?
Biennial wormwood is a forb – basically a non-woody plant that completes its life cycle over two growing seasons. As its name suggests, it’s an annual or biennial plant, meaning it either completes its entire life cycle in one year or takes two years to flower, set seed, and die.
This plant belongs to the Artemisia genus, which includes many aromatic plants like sagebrush and tarragon. However, biennial wormwood is quite different from its more famous cousins.
Where Does It Come From and Where Can You Find It?
Here’s where things get interesting: biennial wormwood isn’t actually native to most of North America. It’s considered non-native in Alaska and Canada, where it has established itself and reproduces without human help. In the lower 48 states, its native status is undefined, but given its widespread distribution, it’s likely non-native there too.
You can find this adaptable plant across an impressive range of locations, from Alaska and all Canadian provinces to most U.S. states, including Arizona, California, Colorado, and stretching all the way to the East Coast states like Maine, New York, and South Carolina.
What Does It Look Like?
Biennial wormwood won’t win any beauty contests, but it has its own understated charm. The plant features silvery-green foliage and produces small, inconspicuous greenish flowers arranged in dense clusters. It’s not the kind of plant that stops traffic, but once you know what to look for, you’ll start spotting it everywhere.
The Wetland Connection
One fascinating aspect of biennial wormwood is how its relationship with water varies dramatically across different regions:
- In Alaska, it’s equally happy in wet and dry spots
- In the Arid West, it actually prefers wetland areas
- In eastern regions like the Atlantic Coast, Eastern Mountains, and Great Plains, it typically sticks to drier, upland areas
- In the Midwest and northern regions, it swings back to preferring wetter conditions
This adaptability explains why the plant has been so successful in establishing itself across such diverse climates and conditions.
Should You Plant It in Your Garden?
Here’s the honest truth: biennial wormwood isn’t typically considered a garden-worthy plant. While its invasive status isn’t definitively established, it has a weedy nature and tends to pop up in disturbed areas rather than well-maintained gardens. It’s wind-pollinated, so it doesn’t offer much for pollinators, and its aesthetic appeal is minimal.
If you’re looking for native alternatives that offer similar adaptability but with better garden credentials, consider these options instead:
- Native Artemisia species like white sage (A. ludoviciana) for western gardens
- Native asters for fall interest and pollinator support
- Local native grasses that provide structure and wildlife habitat
If It Shows Up Anyway
Given its widespread distribution and hardy nature, biennial wormwood might appear in your garden whether you invite it or not. If it does, you don’t need to panic – it’s not aggressively invasive, and since its status varies by region, removal isn’t necessarily urgent. However, if you prefer a more curated garden space, it’s easy enough to pull up since it’s not deeply rooted.
The plant grows in USDA hardiness zones 3-9, thriving in various soil conditions and tolerating both wet and dry situations depending on your region.
The Bottom Line
Biennial wormwood is one of those plants that’s more interesting from an ecological and botanical perspective than a horticultural one. While it demonstrates remarkable adaptability and has successfully established itself across North America, it’s not a plant most gardeners would deliberately choose to grow.
Instead of focusing on this somewhat weedy species, consider exploring the wonderful world of native plants in your area. They’ll give you better garden performance, support local wildlife, and help create the kind of sustainable, beautiful landscape that both you and nature can appreciate.
