Clustered bur-reed are aquatic plants with rootstocks that are native in marshes and swamps throughout North America. Bur-reed is an important source of nutrition for at least 20 species of waterfowl and marsh birds. Clustered bur-reed leaves are alternately stiff and erect or limp and floating. Small white flowers grow in globular clusters that are either male or female. You can grow clustered bur-reed from seeds that have been ripened in a greenhouse. Sowing must occur immediately as the seeds ripen, or the seeds will become too dry to germinate.
Place three to five ripened clustered bur-reed seeds in a small clay pot. Bur-reed seeds are brown when they are ripe. Place the pots in a tray filled with 1.25 inches of cold water. Place the tray with the seeded pots in the refrigerator. Start your clustered bur-reed seeds in April for summer planting.
Keep an eye on the plants and gradually increase the water level in the tray as the seedlings begin to grow. Germination of bur-reed seeds may also occur naturally as they ripen and fall from the plant in mid-summer. The seeds eventually sink to the bottom of the marsh, and, if conditions are favorable, they will germinate.
Remove the plants from the fridge after the seeds are germinated. Thin out the potted seedlings and place the bur-reed plants into individual pots when they are 4 to 5 inches tall. Keep the pots in water.
Plant the individual plants along the side of a stream or in a shallow pond during the end of May or the beginning of June. Bur-reed enjoys full sun, but will tolerate some shade. You can place the roots into wet, rich soil at the edge of a natural water source, or allow them to float in shallow water.
Gather the seeds of your bur-reed plants before they ripen on the plant and place them in a plastic bag filled with moist peat. Place the bag in a cold frame for storage until you are ready for them to germinate. You can ripen the seeds by removing them from the bag and placing them in a greenhouse until they turn brown. This could take several hours.