Summary.In 3 years and in three nurseries, experimental plots sown with conifer seed were weeded by hand at intervals from 1½ to 12 weeks. Assessments of the seedlings at the end of each year showed a reduction in numbers and height only on plots left for 12 weeks between successive weedings. The total time taken to weed plots during the growing season was least for plots weeded at intervals of 3‐4 weeks and greatest for plots weeded at the longest intervals. Data on the total weight of weeds, the total number of weeds, the species composition and the stage of weed growth at weeding are also given and discussed.Essais de désherbage dans les pépin