Plant them as soon as you buy them. Letting them sit on dry shelves is not good for them (or for you if you forget to plant them)
Put the base of the bulb - the lower end approximately six inches deep.
Plant the bulbs approximately 10 to 12 inches apart.
Plant the bulb in the sunshine although ideally, you've planted it so the tops are in the full sun but the roots are shaded by other plants. Lilies like to have cool feet.
You can plant your lily in the garden soil or in containers. It makes no difference to the lily bulb and you'll enjoy it either way. You can even plant lilies in the rock garden as long as you use Lilium cernuum and L. pumilum because they seldom grow taller than 24 inches.
Plant in fall or spring - it makes no difference in my garden. Having said that, if you buy your bulbs in the fall, then plant in the fall and if you purchase in the spring, plant in the spring. Storing a bulb out of the soil for a long time will cause them to dry out and die.
And yes, if you forgot to plant them, they might be dead. There are two ways to tell if they're dead - if they're soft. And if you plant them. If the bulb is hard and firm, plant it no matter how long you've stored it.
I always planted my lily bulbs in the perennial flower garden mixed up with the rest of the perennials. They naturalized out there and multiplied. Try planting lily bulbs with Salvia nemorosa and its cultivars, various Aconitum species and cultivars (Monkshood), Anchusa azurea, Erigeron cultivars, Aster amellus, Echinops bannaticus (Globe Thistle), the taller Geranium species, Polemonium caeruleum (Jacob's Ladder) and Veronica longifolia (a Speedwell species). Plants with grey foliage, such as Artemesia species and Stachys byzantina are also interesting combinations.
You'll often see lily bulbs sprouting, this is acceptable if you plant carefully and don't wreck the growing tips. Hint-backfill the hole carefully and water heavily to force the soil around the sprouts instead of stepping on the planting hole
Shopping Resources for this Page
If you need lily bulbs for planting lilies :-) you can find a wide selection here