North America Native Plant

Hayfield Tarweed

Botanical name: Hemizonia congesta leucocephala

USDA symbol: HECOL2

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Hemizonia leucocephala Tanowitz (HELE3)   

Hayfield Tarweed: A Humble Native Wildflower Worth Getting to Know If you’re looking to add some authentic California character to your native garden, let me introduce you to a plant that might not win any beauty contests but certainly earns its keep: hayfield tarweed (Hemizonia congesta leucocephala). This unassuming annual ...

Rare plant alert!

Region: Conservation status by state

Status: S5T2T3: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘ 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. ⚘

Hayfield Tarweed: A Humble Native Wildflower Worth Getting to Know

If you’re looking to add some authentic California character to your native garden, let me introduce you to a plant that might not win any beauty contests but certainly earns its keep: hayfield tarweed (Hemizonia congesta leucocephala). This unassuming annual wildflower is one of those sleeper natives that quietly does important work in the ecosystem while asking for almost nothing in return.

What Exactly Is Hayfield Tarweed?

Hayfield tarweed is a native California annual forb – basically a non-woody flowering plant that completes its entire life cycle in one growing season. Don’t let the word tarweed put you off; while some of its relatives can be a bit sticky, this particular species is quite well-behaved. You might also see it listed under its synonym Hemizonia leucocephala in older plant references.

As an annual, this plant follows nature’s live fast, bloom bright philosophy, sprouting from seed, flowering, setting seed, and completing its cycle all within one year.

Where Does It Call Home?

This California endemic has chosen the Golden State as its exclusive territory, growing naturally in coastal and inland valley areas. It’s truly a homegrown native, having evolved specifically to thrive in California’s unique climate patterns.

A Note About Conservation

Here’s something important to know: hayfield tarweed has a conservation status that suggests it may be somewhat uncommon in the wild. If you’re interested in growing this native, please make sure to source seeds or plants from reputable native plant nurseries that collect responsibly. Never collect from wild populations, and always ask about the source of your plants.

Why Consider Hayfield Tarweed for Your Garden?

You might be wondering why you’d want to invite a plant called tarweed into your carefully planned native garden. Here’s why this modest wildflower deserves a spot:

  • True California native: It belongs here and supports local ecosystems
  • Pollinator magnet: Those small white to pale yellow flowers attract native bees, butterflies, and other beneficial insects
  • Low maintenance: Once established, it’s quite drought tolerant
  • Authentic wildflower appeal: Perfect for naturalized areas and wildflower meadows
  • Self-sufficient: Will often self-seed for next year’s display

Growing Hayfield Tarweed Successfully

The good news is that hayfield tarweed isn’t particularly fussy about its growing conditions, though like most California natives, it has some preferences:

Ideal Growing Conditions

  • Sunlight: Full sun is best – at least 6 hours of direct sunlight daily
  • Soil: Well-draining soil is essential; it doesn’t tolerate soggy conditions
  • Water: Drought tolerant once established, but appreciates some water during germination
  • Climate: Thrives in USDA hardiness zones 8-10, which covers most of California

Planting and Care Tips

Growing hayfield tarweed is refreshingly straightforward:

  • Timing: Direct seed in fall or early spring when temperatures are cool
  • Seeding: Scatter seeds over prepared soil and lightly rake in
  • Germination: Keep soil slightly moist until seedlings establish
  • Maintenance: Once growing, it needs very little care – perfect for busy gardeners
  • Harvesting seeds: Let some plants go to seed to ensure next year’s display

Perfect Garden Roles

Hayfield tarweed shines in several garden settings:

  • Wildflower meadows: Blends beautifully with other native annuals
  • Native plant gardens: Adds authentic California character
  • Naturalized areas: Great for spots where you want a wild look
  • Pollinator gardens: Provides nectar for native insects

Setting Realistic Expectations

Let’s be honest – hayfield tarweed won’t stop traffic with its dramatic blooms. Its flowers are small and somewhat modest, and the plant itself has a rather humble appearance. But that’s exactly what makes it special. In a world of flashy garden showstoppers, there’s something deeply satisfying about growing a plant that’s all about function and authenticity rather than pure ornamental appeal.

The Bottom Line

Hayfield tarweed might not be the star of your garden, but it’s definitely a valuable supporting player. If you’re creating a native California landscape, establishing pollinator habitat, or simply want to grow something that truly belongs in your local ecosystem, this unassuming annual deserves consideration.

Just remember to source it responsibly, give it the well-draining soil it craves, and then step back and let it do its thing. Sometimes the most rewarding plants are the ones that remind us that gardens don’t always have to be about spectacle – sometimes they can simply be about belonging.

Hayfield Tarweed

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Asterales

Family

Asteraceae Bercht. & J. Presl - Aster family

Genus

Hemizonia DC. - tarweed

Species

Hemizonia congesta DC. - hayfield tarweed

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