It depends on your climate. The more sun they get, the faster they will grow. But the soil must not get too hot, or they will go dormant or the bulbs will rot. I plunge the root ball into the soil in late May, and cover with an inverted 17-inch flat to keep the birds and mice away. It helps if they get shade in the afternoon. Feed and water until they go dormant. After they go dormant, the soil should be allowed to partially dry out, but don't let it get hot. They take about four years to bloom from seed.
Maybe the best way for you is to keep them in the coldframe, in a big pot that does not get too hot, or in a smaller pot that is plunged into sand or gravel. Never let the air get too hot. Use shade cloth or lath. When the plants go dormant, you will be able to dry out the soil very easily by covering the coldframe with something opaque, like plywood. You can't just close the glass, because that will cause very high temperatures.
They need rich soil, water and fertilizer. If you have grown western US Erythroniums, you can grow these.
