Larger Western Mountain Aster: A Late-Season Pollinator Powerhouse for Western Gardens
If you’re looking for a native wildflower that brings color to your garden when most other plants are calling it quits for the season, meet the larger western mountain aster. This unassuming perennial might not win any beauty contests in spring, but come late summer and fall, it transforms into a pollinator magnet that’ll have you wondering why you ever bothered with non-native alternatives.
What Is Larger Western Mountain Aster?
Larger western mountain aster (Symphyotrichum spathulatum var. intermedium) is a native perennial forb that belongs to the sunflower family. Don’t let the fancy botanical name intimidate you – this is simply a hardy, herbaceous plant that lacks woody stems and dies back to the ground each winter, only to cheerfully return the following spring.
You might also encounter this plant listed under its former scientific name, Aster occidentalis var. intermedius, in older gardening references. Same plant, different name – botanists do love to keep us on our toes!
Where Does It Call Home?
This western native has quite the range, naturally occurring across British Columbia, California, Idaho, Montana, Nevada, Oregon, Washington, and Wyoming. It’s perfectly at home in mountainous regions and has adapted beautifully to the variable conditions of western North America.
Being native to both Canada and the lower 48 states, this aster has earned its stripes dealing with everything from alpine conditions to valley floors, making it a remarkably adaptable garden companion.
Why Your Garden (And Local Pollinators) Will Love It
Here’s where larger western mountain aster really shines – it’s a late-season bloomer that provides crucial nectar when many other flowers have finished their show. The purple to lavender daisy-like flowers, typically measuring about half to three-quarters of an inch across, appear just when butterflies, bees, and other pollinators are getting desperate for food sources.
From a gardener’s perspective, this plant offers several compelling benefits:
- Low maintenance once established
- Drought tolerant – perfect for water-wise gardening
- Provides late-season color when gardens need it most
- Supports native pollinator populations
- Self-seeds modestly, filling in naturalistic plantings
Perfect Garden Companions and Landscape Roles
Larger western mountain aster works beautifully in native plant gardens, wildflower meadows, and xeriscape designs. It’s particularly stunning when planted in drifts rather than as solitary specimens – think natural meadow rather than formal border.
This plant excels in:
- Native pollinator gardens
- Mountain and alpine-style landscapes
- Naturalistic prairie or meadow plantings
- Low-water garden designs
- Areas where you want late-season interest
Growing Conditions and Care
One of the best things about larger western mountain aster is its easygoing nature. This plant thrives in full sun and well-drained soils – think of the conditions it evolved in across those western mountain ranges.
Ideal growing conditions:
- Full sun (6+ hours of direct sunlight)
- Well-drained soil (it won’t tolerate soggy conditions)
- USDA hardiness zones 3-8
- Moderate to low water once established
Planting and Care Tips
Getting larger western mountain aster established in your garden is refreshingly straightforward:
Planting: Spring is the ideal time to plant, giving roots time to establish before winter. Space plants about 12-18 inches apart if you’re planting multiples.
Watering: Water regularly the first growing season to help establish roots, then gradually reduce watering. Once established, this plant is quite drought tolerant.
Maintenance: This is where larger western mountain aster really wins points for being low-maintenance. You can deadhead spent flowers if you prefer a tidier look, but leaving them provides seed for birds and allows for natural self-seeding.
Division: Every 3-4 years, you might want to divide clumps in early spring to maintain vigor and prevent overcrowding.
A Few Considerations
While larger western mountain aster is generally well-behaved, it can self-seed in favorable conditions. This is usually a feature rather than a bug in naturalistic gardens, but if you prefer strict control over your plantings, simply deadhead before seeds form.
The plant may look a bit rough around the edges during the heat of summer before it begins blooming, so consider planting it behind or among other perennials that provide earlier season interest.
The Bottom Line
Larger western mountain aster might not be the flashiest plant in the garden center, but it’s exactly the kind of reliable, beneficial native that makes western gardens both beautiful and ecologically valuable. If you’re gardening in its native range and want to support local pollinators while adding late-season color with minimal fuss, this mountain aster deserves a spot in your landscape.
Plus, there’s something deeply satisfying about growing a plant that’s perfectly adapted to your local conditions – it’s like welcoming home a long-lost relative who just happens to feed butterflies.
