North America Native Plant

Timber Milkvetch

Botanical name: Astragalus miser var. crispatus

USDA symbol: ASMIC

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Astragalus decumbens (Nutt. ex Torr. & A. Gray) A. Gray var. crispatus (M.E. Jones) Cronquist & Barneby (ASDEC2)   

Timber Milkvetch: A Tough Western Native for Dry Gardens If you’re looking for a resilient native plant that can handle tough conditions while supporting local wildlife, timber milkvetch might be just what your garden needs. This hardy perennial (Astragalus miser var. crispatus) is a true survivor of the American West, ...

Rare plant alert!

Region: Conservation status by state

Status: S5T3?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ Subspecies or variety is vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. ⚘ Secure: At very low or no risk of extinction in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. ⚘

Timber Milkvetch: A Tough Western Native for Dry Gardens

If you’re looking for a resilient native plant that can handle tough conditions while supporting local wildlife, timber milkvetch might be just what your garden needs. This hardy perennial (Astragalus miser var. crispatus) is a true survivor of the American West, bringing both beauty and ecological benefits to the right landscape.

What Makes Timber Milkvetch Special?

Timber milkvetch is a native perennial that belongs to the legume family, which means it has the superpower of fixing nitrogen in the soil – basically, it’s feeding itself and helping your other plants too! This tough little plant has adapted to some pretty challenging conditions in its natural habitat.

Where Does It Come From?

This plant is native to the western United States, specifically found growing wild in Idaho and Montana. It’s perfectly adapted to the challenging conditions of the intermountain West, where summers can be scorching and winters brutal.

What Does It Look Like?

Timber milkvetch produces clusters of small, cream to white flowers that may not win any beauty contests, but they have a subtle charm that fits perfectly in naturalistic gardens. The silvery-green foliage adds a nice textural contrast to other plants, and the overall growth habit is low and spreading, making it excellent for ground cover applications.

Why Grow Timber Milkvetch?

Here are some compelling reasons to consider this native plant:

  • Drought tolerance: Once established, it needs minimal water
  • Native pollinator support: The flowers attract native bees and other beneficial insects
  • Soil improvement: As a legume, it fixes nitrogen naturally
  • Low maintenance: Perfect for gardeners who want beauty without the fuss
  • Cold hardy: Can handle harsh winters in USDA zones 3-7

Where to Use It in Your Landscape

Timber milkvetch shines in several garden settings:

  • Rock gardens: Its low growth habit and drought tolerance make it perfect for rocky, well-draining areas
  • Xeriscape gardens: An excellent choice for water-wise landscaping
  • Native plant gardens: Pairs beautifully with other western natives
  • Ground cover: Use it to cover difficult slopes or areas where grass struggles

Growing Conditions

This plant is refreshingly easy to please if you give it what it wants:

  • Sunlight: Full sun is best
  • Soil: Well-draining soil is absolutely essential – it hates wet feet
  • Water: Drought tolerant once established, but appreciates occasional deep watering during extreme dry spells
  • Climate: Hardy in USDA zones 3-7

Planting and Care Tips

Getting timber milkvetch established is straightforward:

  • Plant in spring after the last frost
  • Ensure excellent drainage – amend heavy clay soils with coarse sand or gravel
  • Water regularly the first year to help establishment, then back off
  • Avoid fertilizers – as a legume, it prefers lean soils
  • Once established, it’s virtually maintenance-free

A Word of Caution

Before you rush out to find this plant, there’s something important to consider. Timber milkvetch has a relatively limited native range and may have conservation concerns in some areas. If you’re lucky enough to find it available from reputable native plant nurseries, make sure you’re getting responsibly sourced material. Never collect plants from the wild!

The Bottom Line

Timber milkvetch is a fantastic choice for gardeners in its native range who want a low-maintenance, drought-tolerant native plant that supports local ecosystems. While it may not be the showiest plant in your garden, it’s the kind of reliable, hardworking plant that makes everything else look better while quietly doing important ecological work behind the scenes.

If you can source it responsibly and you garden within its native range, timber milkvetch deserves a spot in your sustainable landscape. Your local pollinators – and your water bill – will thank you!

Timber Milkvetch

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Fabales

Family

Fabaceae Lindl. - Pea family

Genus

Astragalus L. - milkvetch

Species

Astragalus miser Douglas ex Hook. - timber milkvetch

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA