The best way to grow waterlilies is from tubers (tropicals) or rhizomes (hardies). I have grown waterlilies from seed....and you can get a tropical to bloom in the first season but a hardy will take two years or longer. Most people who grow them, grow them from divisions, since almost all are hybrids and won't bloom true from seeds. It can be interesting for a just for fun project. Tropical seeds are small...similar to poppy seeds. The way to plant them is to use finely sifted garden soil. Plant them and then cover the soil with some fine sand...like what is used for sand boxes...play sand. Lower carefully in water...like in an aquarium where there are no fish. Grow under lights....germinate usually in 10 to 14 days. However, they can be plagued by algae and fungus. so I wouldn't bother with it if that is your aim to have plants for a watergarden....I'd stick with buying or trading for plants. Hope this helps. I have grown waterlilies for almost 50 years.