The effect of time of sowing and water supply on the bolting and growth of lettuce

Abstract

A statistical experiment was made on May King lettuce grown in a gravel soil in the unheated greenhouse to ascertain the effect of periodic sowings, two levels of water, and alternate drought and saturation with water on bolting and growth.Mature lettuces at a low level of water were darker than those at a high level. The total numbers bolting irrespective of treatment were highest in May to July, and this period coincided with temperatures above 60° F., long days, and decreasing ages from germination to bolting; the largest lettuces were harvested in October to May (excluding mid-January to late March), a period of low temperatures less than 60° F., short days, and increasing ages from germination to harvest.