I said a while back, I was going to post how to start your own seeds. I am sorry I never got around to posting it! Finally, here is the post!
Potting Soil, compost, or other sterile soil
Solid Trays or Plastic Tote lids
Garbage Bags (I prefer white or clear, but black works well too.)
Place Egg cartons on trays or lids. Fill with warm, moist potting soil. You can either warm it near a heater or add warm water to it. One of the best ways to warm the soil is to fill a spray bottle with hot water and spray each cell. You can wait until after you plant the seeds to spray them with water.
Poke a hole in each individual egg cell with finger.
Place one seed per cell if possible. With carrots, lettuce, and other small seeds, it is sometime impossible to get just one seed per cell unless you have a mini seeder.
Label carton so you know which seeds you are planting!
Make sure egg cartons and trays are labeled. Read label to see how long each seed takes to germinate (most are 7-10 days). Check on seeds in a few days. When seeds get their first set of true leaves (which is the second set of leaves the first set of leaves are called cotyledons), you can remove from the garbage bag.
Once removed from bag, continue watering until the seedlings become large enough to transplant in your garden. You may want to harden off the seeds before you plant them in the garden. Hardening off is a way for the seeds to get used to less than ideal and different conditions outside. One way to harden them off is to allow them to set outside a few days in their egg cartons before transplanting.
Transplant seedlings to larger containers or directly in ground in the garden.