Heermann's tarweed
Holocarpha heermannii
Last reviewed: September 2026
Heermann's tarweed (Holocarpha heermannii) is a annual forb native to CA. It blooms in July, August, and September. The flowers draw bees.
Toxicity unknown
Heermann's tarweed (Holocarpha heermannii) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
low
Size
8"–24" H × 8"–14" W
Bloom
Jul, Aug, Sep
Native to
CA
Pollinators
bees
Before you buy
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A sticky, resinous annual tarweed with narrow leaves and small yellow daisy flowers blooming in late summer when most other annuals have dried up. Has an informal, weedy habit typical of late-season tarweeds on dry foothill slopes.
Growing Heermann's tarweed
Grow Heermann's tarweed in full sun and low water. Mature plants reach 8 to 24 inches tall and spread 8 to 14 inches wide.
Wildlife value
Provides a rare late-summer nectar source for native bees when the surrounding grassland has already gone dormant.
Common questions
- How much sun does Heermann's tarweed need?
- Heermann's tarweed grows best in full sun conditions.
- When does Heermann's tarweed bloom?
- Heermann's tarweed blooms in July, August, and September.
- Where is Heermann's tarweed native?
- Heermann's tarweed (Holocarpha heermannii) is native to CA, per the World Checklist of Vascular Plants (Kew).
- What pollinators does Heermann's tarweed attract?
- Heermann's tarweed draws bees.
Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Ready to grow Heermann's tarweed? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.