annualN. America Native

Coast Tarweed

The Story

Plant Bio

Madia sativa, commonly known as coast tarweed, is an erect annual native to western North America and South America with stiff stems covered in sticky, glandular hairs. The plants produce dense clusters of small yellow flower heads from summer into early fall, releasing a strong, pungent aroma.

The stems and foliage are coated in a visceral resin that deters insect herbivores and traps dust in arid coastal or inland conditions. Heavy production of oil-rich seeds makes it a valuable autumn food source for seed-eating birds.

Uses & Benefits:

Produces small yellow flowers in summer and fall atop coarse, textured stems.

Historically used as an oil-rich seed crop for pinole flour by indigenous peoples.

Provides nutrient-dense seeds for native finches, quail, and small mammals while resisting insect herbivory.

Essentials

At a Glance

Plant Type

Annual

Height

94"

Width

24"

Light

Full Sun

Zones

6, 7, 8, 9, 10

Water

Low

Humidity

Tolerates coastal maritime conditions

Lifespan

Annual

Native To

Western North America, South America

Toxicity

Non-toxic (can cause skin irritation)

Bloom period

Summer – Early fall

In flower about 4 months of the year

Planting

How to Grow

Select a full-sun location with well-draining sandy, loamy, or clay soil.
Sow seeds directly outdoors in early spring, lightly pressing them into bare soil.
Water sparingly during germination until roots establish.
Cease watering once plants reach active growth to prevent root rot.

Pro Tip

Withhold summer irrigation once seedlings establish, as wet soil causes weak, leggy stems and encourages fatal root rot.

Keep It Thriving

Care Guide

Do

Provide full sun exposure throughout the growing season.
Ensure high soil drainage to protect root systems.
Mow or pull plants before seed heads ripen if self-seeding must be controlled.

Don't

Do not overwater or use automatic overhead sprinklers.
Do not apply excess fertilizer, which induces weak, rank stem growth.
Do not handle plants bare-handed if susceptible to resinous contact dermatitis.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Harvest
Pest Check
Propagate
Prune

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Wildlife gardensMeadow plantingsNative restoration sitesCoastal gardens

Companion Plants

Eschscholzia californica Layia platyglossa Lupinus nanus

Multiply

Propagation Methods

Good to Know

Common Questions

Coast Tarweed questions

What zones can Coast Tarweed grow in?

Coast Tarweed is an annual: it grows, flowers and sets seed in one season, so winter cold doesn't limit where it grows. Gardeners in any zone can grow it by planting at the right time, usually after the last spring frost.

Is Coast Tarweed deer resistant?

Not reliably. Deer may browse Coast Tarweed, especially tender spring growth — plan on repellents or fencing where pressure is high.

When does Coast Tarweed bloom?

Coast Tarweed typically blooms from early summer to early fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Coast Tarweed need full sun?

Coast Tarweed does best in full sun (6+ hours).

Is Coast Tarweed drought tolerant?

Yes — once established (usually after the first full season), Coast Tarweed handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.