The pattern of seasonal growth and the relation of growth rate to colony size were studied in four foliose and two crustose species of saxicolous lichens. A new method of measuring growth was used whereby the advance of a sample of lobes along millimetres marked on the substrate was measured under a magnification of × 10. Three peaks of growth were found (in March, June and November) for the foliose species and a single peak (in May–August) for the crustose species. The peaks of growth corresponded approximately to peaks of rainfall. Growth rate in relation to increasing colony size fell in a smooth exponential curve when expressed on a cm2/cm2/unit time basis. This result is consistent with a linear radial rate for most of the thallus sizes for the six species. There is also evidence for an exponential increase in growth rate initially until about 1.5 cm thallus diameter in two of the species when the linear radial rate is achieved.