North America Native Plant

San Joaquin Tarweed

Botanical name: Holocarpha obconica

USDA symbol: HOOB

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

San Joaquin Tarweed: A Golden Native for California Gardens Meet the San Joaquin tarweed (Holocarpha obconica), a charming little annual that’s as tough as it is beautiful. This native California wildflower might not win any beauty contests against flashy garden favorites, but it’s got something special that makes it a ...

San Joaquin Tarweed: A Golden Native for California Gardens

Meet the San Joaquin tarweed (Holocarpha obconica), a charming little annual that’s as tough as it is beautiful. This native California wildflower might not win any beauty contests against flashy garden favorites, but it’s got something special that makes it a true gem for wildlife-loving gardeners.

What Makes San Joaquin Tarweed Special?

San Joaquin tarweed is a native annual forb that belongs exclusively to California’s landscape. As its name suggests, this plucky little plant calls the San Joaquin Valley home, though you’ll find it scattered throughout other parts of California as well. It’s what botanists call a forb – basically a fancy way of saying it’s an herbaceous plant that doesn’t develop woody stems like shrubs or trees.

This golden-flowered beauty produces small, cheerful yellow blooms that might remind you of tiny sunflowers. The flowers appear in clusters and create a lovely carpet of gold when planted in groups.

Where Does It Come From?

San Joaquin tarweed is a true California native, found naturally growing throughout the state. It’s particularly at home in the Central Valley and surrounding foothills, where it has adapted to the Mediterranean climate and challenging growing conditions that many other plants simply can’t handle.

Why Plant San Joaquin Tarweed in Your Garden?

Here are some compelling reasons to consider adding this native beauty to your landscape:

  • Pollinator magnet: Native bees, butterflies, and other beneficial insects absolutely love the nectar-rich flowers
  • Drought tolerant: Once established, it thrives with minimal water – perfect for California’s dry summers
  • Low maintenance: Being an annual, it completes its life cycle in one year and often self-seeds for next season
  • Native plant benefits: Supports local ecosystems and provides food for native wildlife
  • Extended bloom time: Flowers typically appear in late summer and fall when many other plants are winding down

Perfect Garden Situations

San Joaquin tarweed shines in several garden settings:

  • Native California plant gardens
  • Wildlife and pollinator gardens
  • Naturalized meadow areas
  • Xeriscaped landscapes
  • Restoration projects
  • Areas where you want seasonal color without ongoing maintenance

Growing Conditions and Care

The beauty of San Joaquin tarweed lies in its simplicity. This plant has evolved to thrive in California’s challenging conditions, making it remarkably easy to grow:

Sunlight: Full sun is essential – this plant loves to bask in California sunshine

Soil: Well-draining soil is key. It’s not picky about soil type and can handle everything from sandy to clay soils as long as water doesn’t sit around the roots

Water: Drought tolerant once established, but appreciates occasional deep watering during extended dry periods

Climate: Thrives in USDA hardiness zones 8-10, perfectly suited to California’s Mediterranean climate

Planting and Care Tips

Getting San Joaquin tarweed established in your garden is refreshingly straightforward:

  • When to plant: Direct seed in fall for best results, allowing natural winter rains to support germination
  • Seeding: Scatter seeds directly where you want plants to grow – they don’t transplant well
  • Spacing: Allow plants plenty of room to spread naturally
  • Maintenance: Minimal care needed once established; let plants go to seed if you want them to return next year
  • Watering: Water lightly until germination, then reduce frequency as plants establish

A Few Things to Consider

While San Joaquin tarweed is generally wonderful, there are a few things to keep in mind:

As an annual, plants will complete their life cycle in one growing season. However, if you let them go to seed, you’ll likely see new plants the following year. The flowers, while charming, are quite small and might get lost in a formal garden setting – they’re best appreciated in more naturalized landscapes.

Some people find the plant’s natural tarweed scent a bit strong, especially on warm days, though many gardeners actually enjoy this aromatic quality.

Supporting California’s Native Ecosystem

By choosing San Joaquin tarweed for your garden, you’re doing more than just adding pretty flowers. You’re supporting California’s native ecosystem, providing crucial habitat for pollinators, and helping preserve a piece of the state’s natural heritage. In a world where native habitats are increasingly under pressure, every garden that welcomes native plants makes a difference.

Whether you’re creating a dedicated native garden or just looking to add some easy-care, wildlife-friendly plants to your landscape, San Joaquin tarweed offers a perfect blend of beauty, resilience, and ecological value that’s hard to beat.

San Joaquin 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

Holocarpha Greene - tarweed

Species

Holocarpha obconica (J.C. Clausen & D.D. Keck) D.D. Keck - San Joaquin tarweed

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