Great Valley Phacelia, scientifically known as Phacelia ciliata, is a native annual herb that brings beauty and ecological benefits to California’s diverse landscapes. This plant offers gardeners an opportunity to cultivate California’s natural heritage. Its attractive blooms and adaptability make it a noteworthy addition to various garden settings, especially for those interested in supporting local ecosystems.
Understanding Great Valley Phacelia
Phacelia ciliata is an annual herb typically growing erect up to two feet. Its stems can be branching or unbranched, often covered with fine hairs and sometimes glandular. The plant’s leaves are oblong or oval, reaching up to 15 centimeters in length, with larger ones often divided into lobed or toothed leaflets.
The flowers of Great Valley Phacelia appear in one-sided, curving or coiling clusters known as cymes. Each flower is funnel- or bell-shaped, displaying a blue or lavender-blue corolla with a pale throat. These blooms have deeply veined, hair-lined sepals and can be about one inch across.
Where Great Valley Phacelia Grows
Great Valley Phacelia is native to California, thriving across various regions, including coastal mountain ranges, the Central Valley, and the Sierra Nevada foothills. Its natural distribution extends south into Baja California. It is commonly found in grasslands and on low mountain slopes.
This species prefers full sun, though it can tolerate partial shade. It is well-adapted to drought once established, thriving with between 7 to 18 inches of annual precipitation. It flourishes in a range of soil types, including clays, sandy loams, and gravelly slopes, and can tolerate moderate salinity. Great Valley Phacelia is found at elevations from sea level up to 5,000 feet.
Conservation Status
Great Valley Phacelia (Phacelia ciliata) is not listed as endangered or threatened. However, one of its subspecies, Phacelia ciliata var. opaca, also known as Merced Phacelia, is recognized by the California Native Plant Society (CNPS) with a Rare Plant Rank of 3.2. This designation indicates it is rare, threatened, or endangered within California, and further information is needed regarding its status.
While Phacelia ciliata is stable, other Phacelia species face threats such as habitat loss and degradation. Competition from non-native plants and the impact of off-road vehicle use are common challenges for many native California flora.
Growing Great Valley Phacelia
Great Valley Phacelia is grown from seed, best established by direct sowing. Seeds can be sown in the fall, ideally after the first significant rains, allowing them to undergo natural stratification over winter for better spring germination. Alternatively, spring sowing is possible after the last frost, though blooms might appear slightly later.
To prepare the soil, loosen it to a depth of 6 to 8 inches and incorporate compost or well-rotted manure to enhance fertility and drainage. It prefers a neutral to slightly alkaline pH between 6.0 and 7.5. For sowing, cover the seeds with a thin layer of soil, about 0.5 centimeters deep, as they require darkness to germinate. Space the seeds about 30 centimeters apart for proper growth.
Once established, regular watering during germination and occasional watering during prolonged dry periods will benefit the plants. Avoid overwatering to prevent issues like root rot. The plant typically blooms from winter through spring, and can continue for several months if water is not limited. Great Valley Phacelia self-seeds readily. If uncontrolled spread is a concern, deadheading spent flowers before they produce seeds can help manage its presence.