Seeds of largeseed dodder (Cuscuta indecora, Choisy), field dodder (Cuscuta campestris, Yuncker), and small-seeded dodder (Cuscuta approximata, Bab.) were studied on the basis of (1) germination at different temperatures, and (2) spring emergence of seedlings as related to soil temperature. Small-seeded dodder germinated at 35 to 45 F with maximum germination at 60 F. Largeseed dodder germinated very little and field dodder not at all below 50 F. They germinated best at 60 F and above. Dodder seeds were planted outside at different depths in a sandy loam soil during the autumns of two years. Daily counts on seedling emergence during the spring showed that small-seeded dodder was first to germinate, at a soil temperature of 39 F, largeseed dodder emerged from 7 to 10 days later at a soil temperature of 51 F, and field dodder emerged 2 to 4 days still later. Very few seedlings of the small-seeded dodder emerged after mid-May, but largeseed and field dodders continued to emerge throughout the summer.