Succession planting is a more productive approach that involves continuous propagation of seeds, and waves of transplanting, throughout your growing season.
Vegetable transplants are normally available at garden centres only once per year, in early-mid spring. Such limited availability is based on the principle of growing vegetables as a singular, linear, process: you plant everything, watch it grow, harvest and then the growing season is over. Succession planting is a more productive approach that involves continuous propagation of seeds, and waves of transplanting, throughout your growing season.