Prickly-looking flowers give bur-reed its name and attract birds.
image by USDA-NRCS PLANTS Database/Plants.usda.gov
"Floating bur-reed" (also known as burreed and bur reed), is an emergent aquatic plant --- that is, the plant is rooted in soil but lives in water. The plant keeps its flowers above the waterline, while long, ribbon-like leaves float on the water's surface. Floating bur-reed is a perennial, so it does not die off after one or two growing seasons, and each plant produces both male and female flowers. This flowering habit is part of the plant's reproductive strategy. Grow floating bur-reed from seed and, after it's established, propagate it by division, separating the parent plant into two or more plants.
Sow ripe seeds in pots of rich soil in your greenhouse. Ripe seeds are fresh; they haven't been dried.
Put the pots within larger pots, adding one to two centimeters (a scant half-inch to three-quarters of an inch) of water to the larger pot. The seed pots will be standing in a bath.
Moisten the soil. It should not dry out.
Replant seedlings into separate pots when they are large enough to do so. You should be able to easily work with the plants.
Put the individual pots into water baths again.
Begin increasing the water bath level as the plants grow, eventually ending up with a level that is even with the inside pot's rim.
Transplant the bur-reeds to shallow water in summer at a depth that will allow their leaves to float. Choose an unshaded to only partly shaded location.
Divide plants in spring or autumn, making sure new plants have leaves of their own.
Plant large-sized divisions directly into their permanent place in the landscape.
Pot small divisions and shelter in a cold frame until they are ready to be permanently planted during the summer.