Read the instructions on your seed packets before you begin to learn what depth and spacing each type of seed requires and whether the seed needs full sun or part sun.
Fill a seed-starting tray with seed-growing medium to 1/4 inch from the top of the tray. Moisten the tray by adding lukewarm water until the potting medium becomes saturated. If you're using a compostable peat tray, you can submerge the tray in a pan of water to moisten the soil instead.
Poke holes with a pencil for your seeds, making the holes as deep as the suggested planting depth for that type of seeds. If your seeds need to be scattered on the soil, skip this step.
Drop one seed into each hole or scatter seeds over soil. Cover seeds with potting medium.
Place the lid on your seed-starting tray to naturally create a humid environment for seed starting. Monitor the moisture level in the tray daily until the seeds germinate, within one to two weeks. The soil needs to be quite moist and should naturally remain so with the lid on the seed tray, but you should still check.
Move the seed tray to a south-facing window and remove the cover when the seeds germinate because they need light. Alternately, place the seed tray under a fluorescent plant tray. Rotate the tray in the window once daily so that all seeds receive equal access to light.
Water the seeds so the soil is moist but not wet and keep the seeds inside until they have at least four leaves.
Transplant the seedlings into individual 4-inch pots. Fill the pots with potting medium. Carefully lift the seedlings out of the seed tray by scooping a fork into the seed chamber and lifting up, grasping the seedling leaf with one hand. Shake off excess soil medium. Then create a hole in the 4-inch pot and transplant the seedling into the hole. Water to settle the potting medium.
Allow the seedlings to grow in the 4-inch pots until they become large enough to survive outdoors. Harden off the plants to outside temperature by moving them outside in the sun for several hours a day, then returning them indoors. After two to three days, increase the outside time to half a day, then after another two to three days leave them outside all day. After this you can transplant them into the garden.
Prepare holes in your garden bed for each plant in the plant's preferred planting environment (full sun or part sun). Make the holes 8 inches wide by 4 inches deep.
Remove plants from their containers and break apart the root ball with your fingers. Then place the plant in the prepared hole so it sits in the same depth in the soil as it did in the container. Cover over the roots with soil.
Water the newly transplanted plants to settle the soil. Water until the soil becomes saturated.