Growing Waterlilies From Seed
Though growing waterlilies from seed will not produce exact duplicates of the parents (except with some species lilies), it can be fun! For how to actually create your own new hybrids, see the following articles. Though these articles are about tropical waterlilies, the information applies to hardies as well.
Whether you have made a cross yourself or found a ripening pod made by the bees, you will want to bag it. Plastic bags either zipped or twist-tied loosely around the stem work well as do old panty hose. When the pod ruptures, seeds, each of which will be surrounded by a little floatation aril, will float up into the bag trying to reach the surface of the water.
When the bag is collected, the contents can be placed in a small bucket or other open container with plenty of water. Small white, tan and red seeds will not be viable. Larger dark seeds, gray, green and black are those that can be viable. Within a few days, arils and residual flower parts will rot away and viable seeds will sink to the bottom. Swirling water in the bucket and pouring debris off several times will leave just the seeds.
At this point, tropical seeds can be dried, on paper towels for instance, and stored indefinitely in the refrigerator or they can be planted. Seeds from all hardies (Nymphaea), N. gigantea from the Australian subgenus Anecphya, as with Victoria and Euryale, must be stored in water to remain viable.
Though seeds can be sprouted in warm water and potted individually, we prefer to plant them before they sprout. The number of seeds determines container size, everything from small pots to dish pans to small ponds. We put a layer of soil in the bottom, add water to the brim, level and compact the soil once it has settled from filling with water. We then distribute the seeds as evenly as possible over the soil and drizzle a thin layer of white sand through the water over the seeds. This helps to anchor them and to see them as they sprout. Adding water after putting the seeds are put in can dislodge them, as can placing the container in a pond.
When seedlings have made several floating leaves in smaller containers, we carefully dig them up and pot them individually. In small ponds designed for seedlings we let plants grow to blooming stage and then remove them, either to propagate or discard, making more space for still developing seedlings.
Craig Presnell prefers to pot seeds individually. In his experience, pods that make only a few seeds often have the most promising offspring and he doesn't want to risk losing any in group planting.