Bud initiation and optimum harvest date in Brussels sprouts

For six cultivars of Brussels sprouts ( Brassica oleracea var. gemmifera) with a decreasing degree of earliness, or optimum harvest date, the time of bud initiation was determined during two seasons. Fifty percent of the plants had initiated buds between 60 and 75 days after planting (DAP) in 1994 and between 70 and 86 DAP in 1995. The sequence of cultivars in time of bud initiation was the same as for the time of optimum harvest date. There appeared to be a fixed relation between the period from planting to bud initiation and the period from planting to optimum harvest date. The time of optimum harvest can, thus, be predicted after bud initiation. One day delay in bud initiation delayed the optimum harvest date by 2.4 days. Factors influencing bud initiation are discussed.