In a perfect world, all gardeners would have their own greenhouses. Gardeners could start all of their seedlings for vegetables, herbs and flowers and watch them from the time the seed is planted until the vegetable comes out of the garden in the fall. Having total control over your seedlings as they grow gives you a great deal of satisfaction, but there are a few things you should know before you start pouring dirt into six-packs and tossing in some seeds.
Pour water, preferably room temperature, into large trays to the depth of one inch. Place the six-pack trays in a large tray. Fill the six-packs with potting soil and level off, but don't press soil down. Allow time for the water to soak into the soil; the trays will no longer float when the water has soaked in.
Press a small indentation in each pot, depending on how deep the seed is to be planted. The back of the seed packet gives you the specific depth. Pour out the seeds into the palm of your nondominant hand and use the fingers of your dominant hand to place the seed into each indentation. Cover the seeds per the directions on the seed packet. Before starting on another seed packet, label the ones you have already planted with the labels and markers.
Plant all of your seeds, labeling them as you go.
Place the entire tray of planted six-packs atop the grower's mat and plug in the mat. The grower's mat is designed to hold an even temperature for even germination. Some seeds do not need the grower's mat: check the back of the seed packet for germination temperatures; the mat keeps an even 70 to 72 degrees.
Add water to the large tray every other day to a depth of three-quarters inch.
Place fans to keep air moving around the trays. If the air is stagnant, mold and mildew will develop, which will prevent or stunt the seedlings as they emerge. During warm days you can open the door or vents to move air sufficiently.