http://durgan.org/2019/May%202019/16%20May%202019%20Planting%20carrot%20seeds/HTML/ 16 May 2019 Planting carrot seeds
Optimal soil temperature: 7-30°C (45-85°F) for carrot seed germination. Above they will not germinate and a hot Sun beating down can easily rise above that. The board method keeps a cool temperature and insures the carrot seed does not dry before germination. Also watering with a can pouring water on the board allows enough water to pass onto the seeds insuring they do not dry out. The board method can be used to advantage on other seeds to improve germination.