Hi wertach,

Well, usually a little heat is helpful for seed germination but not necessary after germination. After the seeds have germinated, they usually grow better at lower temperatures (about 65 to 70 degrees F.) Heat will cause a plant to grow faster, requiring more light to balance that rapid growth. Unless you feel that you can supply lots of light, youâÂÂll be better off keeping things on the cool side. Keeping the temperature cooler will help to prevent weak and leggy plants.

Hope this is helpful,

Art

Agree with Art.

After germination, that area might be too hot, for the starting container to have contact with the top of the heater. But you can check it with a kitchen thermometer. After germination you will need a temperatures of about 55 -65F. Warmer temperature encourage faster growth.