Calochortus venustus aka Butterfly Mariposa Lily

Calochortus venustus is a bulb from California in the lily family, Liliaceae. Its common name is butterfly mariposa lily. It grows in a temperate climate within its native range. Wild plants occur in grasslands and mixed evergreen forests. They grow in light, sandy ground, often formed from granite. Records place its habitat below about 7,874 feet [2,400 metres].

This plant grows to about 2 feet [0.6 metres] tall. Its spread reaches about 0.33 feet [0.1 metres]. The bulb lies below ground and has a summer dormant period. Its leaves die back during that summer rest. Plants For A Future gives June to July as its flowering season. Each flower has both male and female organs. Insects pollinate the flowers.

Give it full sun and deep, fertile soil that drains well. Sandy soil suits it, though loam is also suitable. It accepts mildly acid, neutral, and mildly alkaline ground. It can grow in dry or moist soil. However, its water needs change through the year. Keep it fairly dry from flowering until late winter. Wet ground poses a problem, above all in winter. The source rates it for USDA zones 3–7. Cold tolerance does not remove its need for sharp drainage.

Growing this bulb in Britain can be difficult despite its cold hardiness. A bulb frame offers one way to manage its conditions. A sunny spot beside a south-facing wall is another option. Avoid crowding it with nearby plants. The source also describes lifting bulbs after the leaves die. These can stay in a cool, dry place until spring planting. Advice on replanting time differs, so this is not a settled method.

Seed offers another route to new plants. Sow ripe seed promptly, or sow in early spring. Use a cold frame and a mix that drains freely. Spring-sown seed may benefit from a cold treatment. Leave young plants undisturbed for their first two growing years. Their first dormant spell needs care: excess moisture can cause rot. Too much drying can also kill the seedlings. The cooked bulb has a sweet taste and is edible. Plants For A Future lists no known hazards or medicinal uses. That hazard statement does not establish safety for pets.