Hoary Alyssum: The Gray-Green Volunteer You Might Already Have
If you’ve ever noticed clusters of tiny white flowers sprouting up in disturbed garden areas, along walkways, or in that forgotten corner of your yard, you might have made the acquaintance of hoary alyssum (Berteroa incana). This European native has made itself quite at home across North America, and while it’s not exactly a garden showstopper, it’s certainly made its presence known in the plant world.
What Exactly Is Hoary Alyssum?
Hoary alyssum, also known as hoary false madwort, is a biennial plant that completes its life cycle over two years. The hoary in its name refers to the soft, grayish hairs that give the entire plant a slightly fuzzy, silver-green appearance. These tiny hairs are actually the plant’s way of conserving moisture – pretty clever for a species that often grows in less-than-ideal conditions.
This member of the mustard family typically grows 1-3 feet tall and has a spreading habit that allows it to form colonies over time. Its small, four-petaled white flowers bloom in dense, elongated clusters from late spring through early fall.
Where You’ll Find It
Originally from Europe and western Asia, hoary alyssum has established itself as a non-native species throughout much of North America. It’s been documented in numerous states and provinces, from Alaska down to Arkansas, and from coast to coast including Alberta, British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan, and dozens of U.S. states.
This adaptable plant thrives in disturbed soils, making roadsides, construction sites, abandoned lots, and the edges of cultivated areas its preferred real estate.
Garden Considerations: To Plant or Not to Plant?
Here’s where things get interesting. While hoary alyssum isn’t currently classified as invasive in most areas, it’s definitely what you’d call an enthusiastic self-seeder. It reproduces spontaneously in the wild and tends to persist wherever it lands. For most gardeners, this plant is more likely to show up uninvited rather than being intentionally planted.
The Case Against Intentional Planting:
- Aggressive self-seeding can lead to unwanted spread
- Not particularly ornamental compared to native alternatives
- May compete with desired native plants
- Can be difficult to control once established
If It’s Already There:
If hoary alyssum has already taken up residence in your garden, you’ll find it’s relatively easy to manage with regular weeding, especially if you catch it before it sets seed. The shallow root system makes young plants fairly easy to pull.
Growing Conditions and Care
Should you find yourself with hoary alyssum (invited or not), here’s what it prefers:
- Soil: Tolerates poor, disturbed soils but adapts to various soil types
- Sunlight: Full sun to partial shade
- Water: Drought tolerant once established
- Hardiness: USDA zones 3-8
- Maintenance: Requires little care but deadheading prevents excessive self-seeding
Wildlife and Pollinator Value
While not a powerhouse for native wildlife, hoary alyssum’s small flowers do attract some pollinators, particularly small flies and occasional small bees. However, native alternatives typically provide much more significant benefits to local ecosystems.
Better Native Alternatives
If you’re drawn to the delicate white flower clusters of hoary alyssum, consider these native alternatives that offer similar aesthetics with greater ecological value:
- Wild bergamot – offers white flower clusters and attracts beneficial insects
- White wild indigo – provides white flower spikes and supports native butterflies
- Culver’s root – features tall white flower spikes beloved by pollinators
- Wild quinine – offers white flower heads with excellent wildlife value
The Bottom Line
Hoary alyssum is one of those plants that’s neither hero nor villain – it’s simply making its way in the world. While it won’t win any garden design awards, it’s not causing major ecological havoc either. If you encounter it in your garden, you can choose to leave it be, manage it through selective weeding, or remove it entirely in favor of native alternatives.
The key is being intentional about your choices. If you’re looking to support local ecosystems and create a truly sustainable garden, native plants will always be your best bet. But if hoary alyssum has already settled into a corner of your yard and isn’t bothering anything, sometimes the most sustainable choice is simply to let it be – just keep an eye on it to prevent any unwanted spreading adventures.
