Tomatoes and peppers are hot weather plants. They really prefer it when the temperatures are warm. So that means if it's not warm where you're growing, it's going to take longer for them to germinate and grow. That means it is best to help them stay warm and their soil moist if you want them to do well.

These plants are some of the few that I do use the clear tray covers on when they are germinating. The lights above them help them to stay nice and warm inside the trays, which helps them to grow. But I've found that it is best if you do this with seedling trays that are not made of materials like peat or coconut, as those mold very quickly. I've never been successful with those kinds of pots under the clear covers. As long as they don't get over-watered, I've not had an issue with the traditional plastic seed cells and regular seedling soil. But if you're using other kinds of pots or material to grow the seeds in, you may run into issues.

Some people swear by adding in a heat mat under the trays to help them keep warm. I haven't had to do this since I grow them indoors and it's pretty warm inside. But if you're doing this in a greenhouse, a basement, or other place that is chilly, you might want to consider it.

Once the plants get a good set or two of true leaves I'll move them from the seedling cells to larger pots so that they have room to grow.