If you have multiple stems, it might be time to dig them up this fall and divide the bulbs. Lilies that have been growing in the same spot for a number of years and have typically done well until this past summer usually is a signal that the entire 'system' is congested below and each individual bulb will require it's own space and resources to perform well.

There's really no need to supply lilies any fertilizer at this time of year because it really isn't in active growth.

I typically fertilize with a granular 5-10-10 fertilizer when the first come up in the spring and another application just before they flower. I also top dress my beds in fall or winter with compost and mulch, which adds to the nutrients my lilies receive.

I hope this helps a bit. Visit the site below for more info!

Cheers,

Riz

Here is a link that might be useful: North American Lily Society

Thank you, Riz. Yes, that is very helpful and informative.

Kate