Tall flatsedge, or Cyperus eragrostis, is a grass-like perennial herb with skinny leaves and long triangular stems. It is native to California, except the desert and Great Basin regions. It has also been found in Louisiana, Mississippi, New Jersey, Oregon, Pennsylvania, South Carolina, Texas and Washington. The flowers are golden-brown or green in color and have rays sticking out from a central point with clusters on the ends. Fruits and flowers spread out, much like the ends of an umbrella do. The plant blooms between the late spring and midsummer.
Choose a planting site that is either in the sun to partial shade or light shade. Clear debris and weeds using a weed killer (follow manufacturer instructions) or hand tools.
Dig holes that are about 3 inches deep with a spade. Drop a bulb in each hole, with its roots pointed down. If you don't know which side the roots are on, place it on its side and it will right itself. Cover with a couple inches of soil.
Keep the soil consistently moist, and do not let it dry out between waterings. If you live in a hot, dry climate, this will mean daily waterings. If you live in a cooler area, you can go a couple of days between watering. Touch the soil to determine moisture content and if it is dry, add water.
Plant tall flatsedge in areas with shallow water, if desired. It does well on the sides of streams and pools in nature.
Expect the flatsedge to grow between 12 and 24 inches high.
Deadhead the plant by pulling off dead blooms if you don't want it to self-sow, creating more plants. It typically drops seeds freely, which causes what are called volunteer seedlings. If this occurs and you don't want the seedlings next season, pull them up by the roots.