Moisten the soil before you sow. It should be damp but not wet—like a wrung-out sponge. This applies to outdoor (direct) sowing, too.
Fill your containers with soil mix. Tamp it down gently, leaving 1/2 inch (12 mm) or so of space at the top.
Check the seed packet for information on how deep to sow the seed. As a rule of thumb, seeds can be planted at a depth of about twice their diameter; thus large seeds such as beans will be sown deeper than miniscule carrot seeds. It is better to err on the side of planting too shallow, however; plant too deep and the seedling won’t be able to reach the soil surface.
If you are sowing larger seeds in containers, poke a hole into the soil using a chopstick or pencil, place one seed in, and cover it with soil. For smaller seeds, sprinkle them on top and scratch them in. Depending on the size of your container, you might plant two to six seeds. Planting extra provides a fallback in case one or more fails to germinate. If you are sowing outdoors, sow a row by creating a trench with the edge of your trowel, and then scatter or place seeds evenly along it. Follow the spacing directions on the seed packet. Of course, you don’t have to plant in straight lines. Blocks or natural-looking drifts also work.
Label your containers or rows if you are sowing more than one type of seed.
Place the containers in a warm, bright area, and wait. (If you cover your trays with a clear dome or plastic bag, you may not even need to water again until the seeds germinate.) Some seeds germinate in days; others take weeks.