Hardiness Zone: 6a
Paul from Detroit, MI
Don't worry about your lilies. It sounds like your lilies are in a good sunny spot, and hopefully you provided them with some good well-drained soil. As long as you see some green foliage now, they will probably be just fine.
As you mentioned, your lilies did flower after you planted them this first year. Right now they are settling in and trying to adjust to their new location.
When lilies are planted in the early spring, they usually produce shorter, later-flowering stems. This is especially true if warm summer weather arrives early. Your lilies will need to pass through another winter in order to get back on schedule and "reset their clocks" to their new growing conditions.
Don't give them any more fertilizer. It's best not to over do it-especially during this first year. Too much will promote weak stems by diverting too much of the lily's energy into above ground growth.
If your original stalks formed seed pods, you can go ahead and cut them off. Leave as much of the leafy stem as possible though, so the plant's energy goes toward building up bulb reserves for next year. Once the stems turn brown and die this fall, you can clip them back to the soil level in order to tidy up your beds.
Over the next two year they will establish themselves and you should see lots of gorgeous blooms.
Asiatic lilies don't add more leaves as they grow-- they add bulk and strength to their bulb for next year. It's growing! Check your local growers about leaving the bulb in the ground over winter.
It probably will not grow much the first year and they only bloom once a year. There is an old saying about perennials that after planting, the first year they sleep, the second year they creep, and the third year they leap, meaning it takes a while for them to get established. We have asiatic lilies and they do grow very slowly. This is their third year and they were full of blooms, very lovely.
Thanks for the responses you have answered my question.