Give your Louts heermannii seeds a cooling treatment of about three weeks before planting them after the last frost. A vegetable crisper or sheltered outdoor storage unit should suffice for this, so long as the seeds are protected from extreme changes in the weather. Ransom Seed Laboratory recommends chilling dormant and fresh seeds for 21 days in temperatures of about 68 degrees Fahrenheit.
Prepare a site that mimics the conditions of Lotus heermannii's natural environments throughout California. These plants, which are found along the Pacific coast, inland riverbanks, and canyon and desert edges below 6000 ft., prefer full sun and moist, nutrient-rich soils that don't flood. Clear out weeds, grass and other established plants to give your Lotus heermannii room to flourish.
Plant your Lotus heermannii seeds about an inch below the soil's surface as soon as danger of frost has passed. Water them well, and keep the soil moist, but not soggy, until you begin to see sprouts. You should begin to see the first signs of the colorful flowers as early as March and and late as October.