Broadleaf arrowhead is aquatic and very cold hardy. Grown in ponds and other water features in the home garden as well as in the wild, this aquatic plant has large, edible roots sometimes referred to as Indian potatoes. The roots also provide food to wildlife, primarily ducks of varying species. The broad leaves emerge above the water surface and the stems grow three-petaled white flowers. The entire plant turns white during dormancy in the fall and winter.
Purchase arrowhead tubers from a nursery or gather wild plants where it is allowed. Dig up the tubers and cut the foliage down to 6 inches before planting.
Plant tubers in fresh water, such as a garden pond, anytime from after the first frost in spring until early autumn. The water depth should be between 1 and 6 inches and the soil must be very moist.
Plant tubers just under the soil surface. Space plants 10 inches apart.
Ensure that the roots of the plant stay submerged in areas where the water line may recede. Water with 1 inch of water daily if necessary in this case.
Harvest the arrowhead 'potatoes' if desired in late summer when the leaves of the plant die back. Use a hoe to gently dislodge them from the soil and allow them to float to the water surface.