Phacelia tanacetifolia aka Fiddleneck

Phacelia tanacetifolia is an annual in the borage family. Gardeners call it fiddleneck or lacy phacelia. Its native range runs from southern Nevada to northern Baja California. It also grows wild in California and Arizona. It grows on open flats and slopes. Gardeners grow it for flowers, wildlife, and green manure.

This fast-growing plant has an upright, bushy form. Garden heights range from about 1–3.3 feet [0.3–1 metre]. The RHS also records extremes of 0.7–3.9 feet [0.2–1.2 metres]. Spread varies between sources, from 0.3–3 feet [0.1–0.9 metres]. Green stems stand upright or lean a little. They are fleshy, with glands and short, stiff hairs. The leaves grow alternately along the stems. Their deep cuts and toothed lobes give a fern-like look. Leaves may reach 0.7 feet [0.2 metres] long. Their colour ranges from green to grey-green.

Flowers appear from spring into summer, though timing varies. Dense clusters curl at the tips of flowering stems. The blooms open in sequence along each cluster. Each bell-shaped flower has joined petals and five hairy sepals. Colours range from soft blue to lavender and purple-blue. Darker stamens and styles project beyond the petals. Bees and other pollinators gather nectar and pollen from them. The plant also supports predatory insects and parasitoids. Each egg-shaped fruit holds two brown seeds with wrinkled surfaces. Ripe fruit drops its seeds onto the ground.

Grow it in full sun and fertile soil that drains well. It tolerates sand, rocky ground, heat, and drought. Waterlogged soil causes problems. The RHS gives it a UK hardiness rating of H4. North Carolina State reports cold tolerance to 18°F. Sow seeds where plants will grow in spring or early autumn. Plants seed themselves freely in sunny sites. No pruning is needed, and pests and diseases are seldom problems.

Use it in meadows, wildlife gardens, and informal flower beds. Growers also sow it as a cover or green manure crop. Its roots include a taproot and a dense fibrous network. Heavy self-seeding can make it weedy in some places. PFAF lists no known food or medicinal uses. Its lack of known hazards conflicts with the RHS warning. The RHS identifies it as a skin allergen. Wear gloves and protective clothing when handling it.