Troy,

I'll assume you have hardy water lilies, like me (same zone; I'm near Kansas City). I haven't looked it up in any aquatics book but I've always started adding fertilizer tabs made for lilies just as soon as I move my plants UP. I overwinter them on the bottom (deepest part) of the pond.

My plants have always preformed really well; in fact, I have too many just after two years. :\

I think I'm seeing some growth on a few of my 12 lily containers, but I'm not really too interested in getting in the water just yet. My water temp was 55 yesterday but we're still getting the occasional snow.

I'll probably add tabs around our last probable frost date, which is mid-April.

Yeah I do have the hardy lilies in the pond. I Just moved them up into the shollow water to get them to start. I will start fertilizing them when it gets warmed up enough to get in the water. 55 is a bit cold to get into.. Thanks for the help.

Fertiliser components are readily soluble in water, set them out early and you will be feeding the algae, before the waterlily gets started.

The moment they are wet, the nitrates will be out of that pot, and quite likely to risk scorching tender new root tips as the plant is just starting up

By allowing new feeder root networks to form, with 2-4 weeks of growing temps, the plant is likely to be budding up, inserting any slow release fertiliser between the growing plant and the root network going about the inside surfaces of the pot it is planted in would be good timing

Odds on, the water will be a more comfortable temperature at which to go shunting pots about a pond, raising them to a height where you can poke a hole, bury the fertiliser within some clay to slow down the fertiliser dissolving, without water dissolving the fertiliser before you can insert it