Chondrus crispus (Irish moss) can be propagated vegetatively in flowing seawater in tanks. Experiments have been conducted in small and medium sized tanks in the greenhouse to determine some of the conditions required for successful vegetative propagation. The factors tested included light, temperature, density, and nutrition. The plants used in these tests were a clone of a single plant (T4) selected on the basis on rapid growth and relative freedom from epiphytes. The use of a single clone reduces problems arising from genetic variability. The paper describes further experiments done with this clone (T4) on a somewhat larger scale, and in outdoor tanks to confirm previous results.NRC publication: Ye