Germination Period for Tomatoes

Temperature

• Tomato seeds generally take one to two weeks to germinate; however, the timing of both germination and the emergence of your tomato seedlings is dependent on temperature. At soil temperatures of 65 to 85 degrees F, germination takes approximately three to four days, and seedling emergence requires approximately six to eight days. A temperature of 75 to 80 degrees F is ideal for germination, according to Iowa State University. Your seeds cannot germinate if temperatures remain below 50 degrees F.

Moisture

• Moisture also affects germination. An inconsistent supply of moisture delays germination, according to Iowa State University. Moisten the growing media before you plant your seeds, then mist the surface of the media, or water your seed trays from the bottom after planting. After watering, cover the trays in clear plastic to keep the environment around the germinating seeds moist.

Light

• Place the trays out of direct sunlight. Your tomatoes do not require light until after germination. Remove the plastic covering from your trays once the seeds sprout and the plants emerge. Place the trays in sunlight in a south-facing window, or provide supplemental light. Once germination occurs, your plants need as much sunlight as possible and temperatures between 60 and 75 degrees F.

Timing

• Start your seeds indoors, six to eight weeks before your planned transplant date, which is usually the predicted last frost date for your location. Since the actual last frost date varies depending on your region, local conditions and yearly weather fluctuations, soil temperatures are a better guide than a strict calendar date for timing your transplanting. Just as with germination, temperature plays a key role in development of your maturing plants. Wait to transplant until you have both warm air and soil temperatures of 60 degrees F or greater; temperatures under 50 degrees F impair tomato growth, can cause immediate problems such as phosphorus deficiency, and can lead to blossom end rot and catfacing -- fruit becoming misshapen with holes on the end -- of fruits later in the season.