lillies that are getting shorter

i have lillies that are getting shorter and shorter every year. I live in a very cold climate. Is it beacuse of the cold or is it another issue? They are now about 1 foot tall. They started out 3 ft tall

Doug says you aren't feeding them nor taking care of them. If they're getting shorter - then they're under stress. You don't say what a "cold" climate is but given that these are a very hardy plant, if you can grow it you can grow it well. Step up the compost feeding (a shovel per plant in the spring will make a huge difference). Yes, you can still do it mid-summer right now to try to boost them for next year.

I'm assuming they're on decent soil (not heavy clay) and well-drained in full sun. In other words, that you're giving them the growing conditions they want to begin with. :-) If not, move 'em this fall.

Good luck - let me know how you do