Vermiculite is a special mineral that becomes exceptionally light and airy when heated. Vermiculite is used most often in seed-starting potting mixes as it is sterile and light enough to provide proper aeration and drainage to young plants. It also doesn't form a crust as it dries, so the seedling can easily push through it to reach the sunlight and air it needs to survive.
Mix 1 part vermiculite with 1 part peat moss in a large bucket. Water the mixture until it is moist and allow it to sit for 30 minutes to absorb any additional moisture and plump up.
Fill seed starting pots with the vermiculite mixture. Sow one to three seeds in the center of each pot and cover with a ¼ to ½ inch layer of pure vermiculite.
Mist the top of the vermiculite in the pots with a spray bottle of water. Cover with plastic wrap and set in a warm place to germinate.
Remove the plastic wrap once seedlings appear. Move the pots to a sunny windowsill and keep the potting mixture moist at all times.
Fertilize with a half-strength liquid fertilizer when the seedlings are two weeks old, as neither vermiculite nor peat moss has natural nutrients for the plants. Continue to apply fertilizer weekly until the plants are transplanted into larger containers.
Prepare large pots when the seedlings produce their second set of true leaves, which is the third set of leaves they grow. Mix together 1 part vermiculite with 1 part compost and 1 part peat moss. Add a balanced slow-release fertilizer to the soil mixture following application instructions on the label.
Moisten the mixture thoroughly then fill the larger pots with the mixture. Dig a hole in the center of the soil deep enough for the seedling that is being transplanted.
Remove the seedling from the starter pot and place into the planting hole in the new pot. Make sure it is sitting at the same soil depth it was at in the seedling pot.
Firm soil around the base of the plant and water well. Keep soil moist at all times and fertilize potted plants every two to four weeks in spring, summer and fall.