Growth rates of two agarophytes: Gracilaria cf. verrucosa and Pterocladia capillacea, and two carrageenophytes: Hypnea musciformis and Hypnea cornuta, were studied under field conditions in the eastern Mediterranean. Growth rate was affected by experimental site conditions, technology of growth and species properties. Dry weight, agar and carrageenan content, melting and dynamic gelling temperatures, and gel strength, were measured. The growth rate and physical properties of the phycocolloids suggest that these algae are potentially good sources of agar and carrageenan. The problems of epiphytes, thallic disintegration and technical difficulties are described and discussed.