Poa annua L. is a turfgrass commonly found on golf course putting greens, as well as many other environments in temperate regions of the world. Although it can produce a very desirable putting surface, the species is usually considered a weed, in part because it is characterized by continuous flowering during the growing season. Flowering at the low mowing heights of a golf green, is detrimental to the putting quality of the green and the stress tolerance of the plants. However, many individuals of P. annua flower only in the spring. We conducted this inheritance study to investigate the genetic control of flowering pattern in four representative genotypes, then relate the information to the ecology of the species in golf course environment, and propose improvements for P. annua breeding. One annual and three perennial tetraploid P. annua genotypes were crossed in all combinations. F1, F2, and in most cases F3 populations were grown and observed in field or greenhouse conditions over 1 to 3 yr. Each plant was rated for flowering pattern during the growing season. A genetic model involving one locus and two alleles with continual flowering completely dominant to seasonal flowering is proposed for control of flowering pattern based on F2 populations exhibiting 3:1 ratios of continual to seasonal flowering pattern types. Three distinct F3 populations are produced from F2 progeny: all continual flowering, all seasonal flowering, and segregating 3:1 continual to seasonal, similar to the F2 generation. There may also be evidence of modifying loci and maternal effects in some populations. This simple inheritance may explain the high heritability of flowering traits and rapid evolution of plant types in golf course turfgrass. Qualitative inheritance also provides the opportunity for efficient selection of desirable seasonal flowering P. annua plants.