North America Native Plant

Wetherill’s Milkvetch

Botanical name: Astragalus wetherillii

USDA symbol: ASWE2

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Wetherill’s Milkvetch: A Rare Gem for Dedicated Native Plant Gardeners If you’re the type of gardener who gets excited about growing something truly special and rare, Wetherill’s milkvetch (Astragalus wetherillii) might just be your next obsession. This little-known perennial is one of those plants that makes you feel like you’re ...

Rare plant alert!

Region: Conservation status by state

Status: S3: Status is uncertain but is somewhere between the following rankings: 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 ⚘

Wetherill’s Milkvetch: A Rare Gem for Dedicated Native Plant Gardeners

If you’re the type of gardener who gets excited about growing something truly special and rare, Wetherill’s milkvetch (Astragalus wetherillii) might just be your next obsession. This little-known perennial is one of those plants that makes you feel like you’re part of an exclusive club – and for good reason!

What Makes Wetherill’s Milkvetch Special?

Wetherill’s milkvetch is a native wildflower that calls the rugged landscapes of Colorado and Utah home. This perennial produces delicate purple to pink pea-like flowers that may be small in stature but are big on charm. The compound leaves give it a feathery, delicate appearance that contrasts beautifully with its hardy nature.

This plant is found naturally in Colorado and Utah, where it has adapted to some pretty challenging growing conditions in the Colorado Plateau region.

A Word of Caution: Rarity Matters

Before we dive into growing tips, here’s something important you need to know: Wetherill’s milkvetch has a Global Conservation Status of S3, which means it’s considered vulnerable. This typically means there are only 21 to 100 occurrences or between 3,000 and 10,000 individuals in the wild. Pretty exclusive, right?

If you’re determined to grow this rare beauty, please only source it responsibly from reputable native plant nurseries that propagate their own stock rather than wild-collecting. Never, ever dig plants from the wild – that’s a big no-no for conservation!

Why Grow Wetherill’s Milkvetch?

So why would you want to tackle growing this challenging little plant? Here are some compelling reasons:

  • You’ll be supporting native plant conservation efforts
  • It attracts native bees and other small pollinators to your garden
  • Perfect for specialized native plant collections
  • Adds authentic Colorado Plateau character to rock gardens
  • Low-maintenance once established (if you can get it established!)

Growing Conditions: Not for the Faint of Heart

Let’s be honest – Wetherill’s milkvetch isn’t going to be happy in your typical suburban flower bed. This plant has very specific needs that mirror its native habitat:

  • Soil: Well-draining sandy or rocky soils are absolutely essential
  • Sun: Full sun exposure
  • Water: Minimal water once established – think desert conditions
  • Climate: Hardy in USDA zones 4-7

Best Garden Settings

This isn’t a plant for every garden, but it can shine in the right setting:

  • Rock gardens with excellent drainage
  • Xeriscapes and drought-tolerant landscapes
  • Native plant collections focused on Colorado Plateau species
  • Specialized conservation gardens

Planting and Care Tips

Growing Wetherill’s milkvetch successfully requires patience and attention to detail:

  • Plant in spring after the last frost
  • Ensure perfect drainage – consider raised beds or slopes
  • Start with small plants rather than seeds for better success rates
  • Water sparingly, even when establishing
  • Avoid fertilizers – this plant prefers lean conditions
  • Mulch with gravel or small stones rather than organic mulch

The Bottom Line

Wetherill’s milkvetch is definitely not a beginner’s plant, but for dedicated native plant enthusiasts, it offers the chance to grow something truly special while contributing to conservation efforts. The delicate flowers and unique character make it a conversation starter, and knowing you’re helping preserve a vulnerable species adds extra meaning to your gardening efforts.

Just remember: only source this plant responsibly, be prepared for some trial and error, and celebrate small victories. Sometimes the most rewarding plants are the ones that challenge us the most!

Wetherill’s 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 wetherillii M.E. Jones - Wetherill's milkvetch

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