How to Start Seeds Indoors

Choose a seed-starting mix for your seeds.

Seed-starting mix (or germinating mix) is a specially formulated growing medium that promotes healthy seedlings. The most practical seed-starting mediums for gardeners are the commercially prepared soilless or peatlite mixes that are sold in most garden stores.

Don’t use garden soil to start seeds indoors. Garden soil isn’t light enough and may contain insects or diseases that can kill your tender seedlings.

Add warm water to moisten the seed starting mix.

Soilless mixes are dusty and difficult to wet initially. Pour the mix into a plastic bag, and then add enough warm water to moisten the mix but not turn it into a drippy mud pie. Combine the water and growing medium with your hands or a strong wooden spoon, closing off the opening of the bag as much as possible to keep the dust in.

Fill a shallow tray with moistened growing medium to within 1/2 inch of the top of the container.

Any container that holds several inches of soil and that you can punch drainage holes in is suitable for growing seedlings. Low-cost possibilities include cleaned milk cartons, paper or Styrofoam cups, cottage-cheese containers, and homemade wooden flats, which are shallow, wide, seedling trays.

Garden stores and most mail-order garden catalogs sell a wide variety of plastic, fiber, peat, and Styrofoam flats and containers that satisfy just about any budget. You can even purchase pots made out of cow manure.

To sow seeds in flats, first make shallow furrows (rowlike impressions) with a blunt stick or by pressing the narrow edge of a ruler into the medium.

Sow small seeds, such as lettuce, at about five to eight seeds per inch if you intend to transplant them into different containers soon after they come up. Sow larger seeds, such as melons, at three to four seeds per inch.

Sow seeds more sparingly, at three to four seeds per inch, if you intend to thin and leave them in the same container (rather than transplant into a larger container).

To sow seeds in individual containers, place two to four seeds in each container.

Later, thin the seedlings, leaving the strongest one.

After sowing the seeds at the correct depth, cover them with fine potting soil or vermiculite.

Label each row or container because many seedlings look alike. You can purchase labels from a nursery or through a mail-order catalog, or you can use old ones from previously purchased nursery transplants.

Water the seeds gently with a mister or spray bottle.

A strong stream of water can wash seeds into one section of the container or move them too deeply into the soil.

Cover the container with a sheet of clear plastic or a plastic bag to hold in the moisture.

If necessary, use small stakes to prop up the plastic so it doesn’t rest on top of the soil.

Place the planted containers in a warm spot.

Some warm spots include the top of your refrigerator or near your furnace. You also can buy heating cables or mats that keep the soil warm from below. Follow the package instructions carefully.

Never put containers in direct sun; the plastic cover holds in the heat, cooking your seeds to death.

Check the containers daily to make sure they're still moist but not so wet that they mold.

If you see signs of mold, loosen the cover and let air in; the mold should disappear.

When the first green shoots emerge, remove the plastic cover and move your seedlings to a spot that provides plenty of light and the proper growing conditions for that plant.

Until seedlings emerge from the soil, light is unnecessary, with the exception of lettuce and celery seeds.

To thin plants, snip out extra seedlings at the soil line with a pair of scissors.

After seedlings develop their first set of true leaves (or when onions or leeks, which send up a single blade, are 2 inches tall), you need to thin them or move them from shallow flats to larger quarters.