Plant architectural characteristics are under strong genetic regulation. Economically important traits for forage crops such as biomass yield, ground cover and persistence can be improved by selecting for particular aerial architectural characteristics. Here, we present an easily applicable method for the spatiotemporal description of branching patterns in red clover (Trifolium pratense) and perennial ryegrass (Lolium perenne), two of the most important forage crops in Europe. A detailed analysis of genotypes with contrasting branching phenotypes demonstrates that in these species different factors are the main determinants of shoot branching characteristics. In red clover, bud outgrowth and to a lesser extent bud formation explain inter-genotype branching differences. In perennial ryegrass, differences in the capacity to form new buds determined largely the differences between forage and turf types. However, when a set of four forage types was compared in a separate experiment, variation in quantity and pace of bud formation and bud outgrowth explained the differences in aerial architecture. In both crops, branching patterns are likely determined by several processes, and highly branched phenotypes can result from the formation of more buds, an increased probability of bud outgrowth, or a combination of these processes. Furthermore, the presence of more buds is partly caused by more bud outgrowth.