|What should the average daily temperature be for successfully growing started plants such as tomatos and zinnas
|These plants will grow well with temperatures of about 75 degrees during the day and at a minimum of 65 to 68 degrees at night. Your greenhouse will need to be ventilated on sunny days to keep it from overheating, and then heated at night to keep the plants warm enough to avoid stress.
To germinate the seeds, soil temperature will need to be fairly high. Tomatoes germinate quickly at soil temperatures between 75 and 80, zinnias germinate best at a soil temperature of about 70 degrees.