I got brand new calla lilies at Lowes and I'm having trouble starting them.
My Calla Lilies Won’t Grow
Certified GKH Gardening Expert
Did you purchase tubers or a plant?
Both would not be able to be outdoors until danger of frost is past.
You could start the tubers in a pot indoors to give them a head start.
Use an adequate sized container with drainage holes and a good potting mix.
Plant the lily tubers so the tops are exposed with the eyes pointed up.
Water enough so the soil is damp but does not remain soggy.
It may take a few weeks for roots and leaves to began forming.
Here are a few links for you.