Glad you got your waterlilies
I use regular old dark brown Texas dirt, Osmocote green cap fertilizer, & Vigoro 15-30-15 granular fertilizer. Scatter the bottom of your dishpan covering about 1/3 of the pot with the fertilizer, add the dirt, add your plant, & cover the dirt with gravel but don't bury the crown of the water lily. If I have a hardy that is being difficult, I'll switch over to a pot or even a basket with holes. Cover the holes with newspaper or weed barrier cloth & plant (sandwich the fertilizer in the dirt though).
Good luck & hope your summer is a lot warmer
![Cool 8)](https://www.worldwidewatergardeners.org/forum/Smileys/smilies_smf/cool.gif)
Maybe this fall you can bring your plants inside to your basement for overwintering?