It's good that you are planting species seed now while it is still that cold, Arturo. Some lily species seeds benefit greatly from fluctuating temperatures, and some want to germinate more at 50-60°F than 65-70°.
Your Dutch hybrids that have died back will need a cold treatment to sprout again. About 40°F for 60 days(minimum) is optimal, temp can be as low as 30°. Otherwise, keep the bulbs warm (55° or more) and plant them outside in mid to late summer. Planting them outside now or in early summer could begin the cold treatment process because the soil has not warmed sufficiently, and you risk them finishing their cold treatment in the fall before winter arrives, and they might sprout in the fall.
If your Dutch origin hybrids that have died back are L. longiflorum or L. formosanum hybrids, they could come up again this season for you without a cold treatment. Let the soil get almost completely dry for a month (or more), and then resume normal watering.
