This is the yellow version of this much sought-after North American native. Like most lilies, they like a good soil and not too dry in summer. Bulb size: While the regular sized bulbs are 5/8" to 3/4" in diameter and might bloom the first year, these large ones are 1-1/4" to 1 1/2" in diameter, capable for 5-7 blooms in the first season.