The age of achenes at harvest of Heilanthus annuus and H. petiolaris had a significant influence on germination. A majority of germination took place by 21 days. Achene dormancy does not appear to be overcome by using a combination of storage temperatures or times. Helianthus argophyllus had the highest overall germination of 84%, followed by H. debilis ssp. silvestris with 16%, H. petiolaris with 51%, and H. annuus wirh 44%. Despite the large differences in germination percentage, the coefficient of velocity was similar for all species.