Products like Bio-dome help prevent drying out of your seed starting mixture. However, it is easy to over-water the sponges which may lead to seed rot. Aim for damp soil, as in a well wrung-out sponge. Avoid placing your dome in direct sunlight; temps inside the dome will get too high and damage seeds and seedlings. This may also occur when using a heat mat with a dome. If you have an instant thermometer, measure the mixture's temp. It should be 60 F at a minimum but no more than 90 F. (cool season vegetables and early spring flowers germinate at lower temperatures) You may need to put a small gap between the heat mat and the dome. I've used a cooling rack in the past. If you keep your home's temperature at 70 F, you may not need a heat mat although a mat is useful for veggies and flowers that like summer sun. Tiny seeds the size of the period at the end of this sentence should not be covered with soil as they need light to germinate. Gently press them into the seed-starting mixture. Water from the bottom to avoid dislodging uncovered seeds. Larger seeds are covered to a depth that is roughly twice the diameter of the seed. If you need more information, please put up another post with what plants you are trying to start. If you haven't already, please read the instructions that came with your Bio-dome.
