Calochortus uniflorus aka Monterey Mariposa Lily

Calochortus uniflorus is a bulbous plant in the lily family, Liliaceae. Its native range runs from western Oregon to western California. It grows in a temperate climate and survives through an underground bulb. Common names include Monterey mariposa lily and large-flowered star tulip. The RHS calls it one-flowered Mariposa lily. It reaches about 1 foot [0.3 metres] in height. Plants For A Future records it from low, moist meadows.

Flowers appear from April to June, according to Plants For A Future. Each flower has both male and female organs. Insects pollinate the flowers. The supplied species records give no details of flower colour or fruit. They also give no species-level account of the leaves or stems. The RHS lists Calochortus lilacinus as a synonym. This plant is not native to Britain or Ireland.

Give it full sun and deep, fertile soil that drains well. Sandy soil suits it, though loam is also listed as suitable. It accepts mildly acid, neutral, and mildly alkaline soil. Keep nearby plants from crowding it. A spot beside a south-facing wall is one suggested outdoor site. A bulb frame offers more control over moisture. Plants For A Future describes cultivation in Britain as difficult. Cold is less of a problem than wet soil.

Water needs change with the growth cycle, and the cited advice differs. One account calls for ample water while the plant grows. That account then calls for very dry soil after flowering. Another stresses keeping the bulb dry through winter. Both accounts warn against wet conditions during rest. Plants For A Future gives USDA zones 3–7. Seedlings need care during their first dormant spell. Too much water can cause rot, but complete drying can also kill them.

Seeds can be sown fresh or in early spring under cold-frame cover. Use a medium that drains very freely. Germination may take one to six months at 15°C. Leave seedlings in place for their first two years. The bulb is edible raw or cooked, though its food-use rating is low. Plants For A Future reports no known hazards or medicinal uses. That hazard statement does not establish safety for pets. The same source records no weed potential.