Sagittaria species may be planted from bare root stock, by transplanting the tubers, and by seeding directly into wetland soil. Live plant transplants or transplanting tubers are preferred revegetation methods where there is moving water. It takes two years for seed to germinate; planting bare root stock or tubers gives faster revegetation results.
Live Plant Collections: No more than 1/4 of the plants in an area should be collected. A depth of 15 cm (6 in) is sufficiently deep for digging plugs. This will leave enough plants and rhizomes to grow back during the growing season.
Wild plants should be collected from the time leaves emerge in spring until first frost. Plants can be pulled up easily from wet soil. When collecting wild plants, rinse roots gently. Leaves and stems can be clipped from 15 to 25 cm (6 to 10 inches); this allows the plant to allocate more energy into root production. The roots should always remain moist or in water until planted. Plants should be transported and stored in a cool location prior to planting. Water depth should be 0 to 6" and the soils should be wet.
Sagittaria grows prolifically around ponds or wetlands in shallow water. Plug spacing of 25-30 cm will fill in within one growing season. Soil should be kept saturated, with approximately 1 cm of water over the surface of the soil after planting. If water is low in nutrients (oligotrophic), fertilization will speed biomass production and revegetation. Many surface waters are already rich in nutrients (eutrophic), and fertilization is not necessary.
Transplanting tubers: Transplant success may be greater with the tubers than with bare root stock. The little underground potatoes can be separated from the parent plants with a rake, hoe, or shovel. In unconsolidated soils, the tubers can be pulled up by hand by searching around the roots of the plant.
After collecting, the Sagittaria tubers should be kept moist and cool, and stored in peat moss. Wapato tubers are then planted in shallow water, in the same conditions as described above for the whole plants. Tubers should be collected and planted when plants are dormant, in the fall, winter and early spring.
Seeds: Seeds of Sagittaria species take two years to germinate, because they have a double dormancy requiring cold then warm then cold temperatures. Temperature has a multiple role in the regulation of timing of germination. Dormant seeds become nondormant only at specific temperatures, non-dormant seeds have specific temperature requirements for germination, and nondormant seeds of some species are induced into dormancy by certain temperatures. Once Sagittaria seeds germinate, they have fairly high viability.
Procedures for growing Sagittaria seeds in the greenhouse have not been developed at this time; however, Sagittaria seeds can be planted directly in wetlands or ponds. Prepare the area by creating a washboard in shallow water, at mudflat consistency. Seeds should then be scattered on the surface of the soil, as the seeds need sunlight to germinate well. Light and temperature in natural conditions will promote seed germination, and in two years Sagittaria plants will emerge.
