A greenhouse is a great way to get a head start on your gardening, especially in the cold months of winter. Starting seeds in a greenhouse will give your plants a chance to flower and bear fruit faster than those set out as seed. You also can speed up the sprouting process if need be. Greenhouses provide a consistent environment and protect fragile seeds from the dangers of being planted outdoors, like foraging animals and bad weather.
Wrap seeds in a damp paper towel, and place them inside a plastic bag for a few days to prepare them for planting. Or soak them in a bowl of warm water for three hours.
Fill your seed trays with potting soil.
Dig a small hole in each tray section for seeds. Each hole should be about 1 to 2 inches deep and 2 inches wide.
Place the seeds in the holes, and cover them with soil. Place one seed per hole if they are large seeds, such as melons. Place 3 to 4 seeds per hole if they are small seeds, such as marigolds.
Water your seed trays with warm water. Keep the soil around the seeds moist at all times.
Place toothpicks in the soil around the seeds. Drape clear plastic over the seed trays. This will keep the soil warm and moist.
Remove the plastic once the sprouts poke out of the soil.
Allow the seedlings to grow until they are large enough to be planted outside. This will be different for every type of plant.