Wildflowers in Silicon Valley

Wildflower viewing can be one of the most rewarding aspects of hiking. In the Silicon Valley area, cool and wet winters lead into longer, warmer spring days that trigger wildflower blooms. Grasslands and oak woodlands in the region’s open space preserves are popular destinations for hikers wanting to see these blooms.

To protect both the flowers and their pollinators, stay on designated trails and resist the urge to pick or trample any blooms. Taking photos rather than souvenirs helps ensure these natural displays remain for everyone to appreciate.

Below is a color-coded guide to some of the wildflowers you might encounter while hiking in the Silicon Valley area.

White flowers

Common yarrow (Achillea millefolium)

• Description: This flowering plant produces clusters of tiny white heads arranged in flat-topped bunches. It’s known for its fern-like leaves.
• When they bloom: Spring through early summer.
• Where to see them: Look along grassy or disturbed areas in parks like Rancho San Antonio Open Space Preserve or Edgewood County Park.

Popcorn flower (Plagiobothrys sp.)

• Description: Named for the small, fluffy white blooms that resemble popped kernels of corn. These plants are low to the ground, so keep an eye out.
• When they bloom: Early spring to mid-spring.
• Where to see them: Found in open meadows and fields, such as at Almaden Quicksilver County Park.

Shooting star (Primula clevelandii and Primula hendersonii)

• Description: These striking wildflowers have nodding blooms with reflexed petals that range from white to purple, often with a yellow or dark “eye” at the center.
• When they bloom: Late winter through spring, peaking in early to mid-spring.
• Where to see them: Look for them in open woodlands, grassy slopes, and areas with moist springtime soils, such as Almaden Quicksilver or Santa Teresa County Parks.

Red flowers

Indian paintbrush (Castilleja sp.)

• Description: Known for its bright red bracts (specialized leaves that look like petals). The actual flowers are small and tucked within these bracts.
• When they bloom: Typically spring to early summer.
• Where to see them: Sunny, open hillsides in places like Henry W. Coe State Park and Fremont Older Open Space Preserve.

Western columbine (Aquilegia formosa)

• Description: A nodding flower with red outer petals and yellow inner petals; often visited by hummingbirds. “Nodding” in botany means that the flower points downward.
• When they bloom: Late spring to early summer.
• Where to see them: Partially shaded woodland edges, such as at Long Ridge Open Space Preserve.

Orange flowers

California poppy (Eschscholzia californica)

• Description: The state flower of California, easily recognized by its bright orange petals. They often close in cloudy weather or at night.
• When they bloom: Often from mid-February through November, depending on rainfall.
• Where to see them: Sunny fields and slopes throughout Silicon Valley preserves, including Edgewood County Park and along Coyote Ridge.

Sticky monkeyflower (Diplacus aurantiacus)

• Description: Tubular orange blooms, slightly sticky leaves, and a preference for dry, rocky soils.
• When they bloom: Spring through early fall.
• Where to see them: Chaparral and coastal scrub habitats such as in Almaden Quicksilver County Park and Monte Bello Open Space Preserve.

Yellow flowers

Black mustard (Brassica nigra) – nonnative

• Description: A tall, invasive plant with clusters of small yellow flowers. Despite its name, the petals are bright yellow.
• When they bloom: Late winter into spring, often persisting into early summer.
• Where to see them: Disturbed soils, roadsides, and open fields throughout Silicon Valley, including Rancho San Antonio Open Space Preserve, St. Joseph’s Open Space Preserve, and Almaden Quicksilver County Park.

California golden violets (Viola pedunculata)

• Description: Also called Johnny jump-ups, these delicate plants have heart-shaped leaves and yellow petals with dark markings.
• When they bloom: Early spring to mid-spring.
• Where to see them: Grassy slopes and oak woodlands, such as at Santa Teresa County Park.

Goldfields (Lasthenia sp.)

• Description: Small, daisy-like yellow flowers that often form bright carpets. These blooms can cover entire meadows in a good rainy year.
• When they bloom: Early spring.
• Where to see them: Seasonally wet meadows and open grassy areas at Edgewood County Park and Coyote Ridge.

Blue flowers

Blue-eyed grass (Sisyrinchium bellum)

• Description: Though called a “grass,” this is actually in the iris family. The small, six-petaled flowers are typically a vivid purple-blue with a yellow center.
• When they bloom: Late winter into early summer.
• Where to see them: Grassy areas in many local parks, including Foothills Nature Preserve and Rancho San Antonio Open Space Preserve.

Purple (indigo and violet) flowers

Lupine (Lupinus sp.)

• Description: Striking spikes of purple or blueish petals. The leaves are palmate (hand-shaped), giving the plant a distinctive look.
• When they bloom: Spring into early summer.
• Where to see them: Sunny fields and hillsides, especially in Edgewood County Park, Henry W. Coe State Park, and Coyote Ridge.

Owl’s clover (Castilleja exserta)

• Description: A low-growing wildflower with purplish or pinkish clustered bracts. A close relative to the paintbrushes.
• When they bloom: Spring.
• Where to see them: Open grasslands and meadows such as at Edgewood County Park or Coyote Ridge.