It keeps the tender seeds in one convenient location while they get started and allows valuable garden-bed space to be used for larger plants that need the room.
Plastic trays or flats work well because they're inexpensive and easy to obtain. Many also have built-in divider rows to help keep seed types separated. For other types of containers, dividers can be made from wood, cardboard, Plexiglas, even old Venetian mini-blinds.
The entire pot gets planted and breaks down on its own, supplying nutrients as it decomposes.
Scarifying, or cutting or nicking the tip of the seed, gives the seed's energy a place to disperse and start germination. Soak the seeds in water to soften the hull, then use a fingernail file, a pocketknife or even a piece of sandpaper to carefully break though the seed's outer layer.
They feed the developing plant and will turn yellow and fall off on their own. The true leaves, which look different, will follow and signal the right time for transplanting.
Transplant the Seedling
Pull and hold the seedling by the leaf, not the stem. Use the knife to make a new hole in a larger pot or garden bed and plant the seedling. Firm up the soil around the stem and be sure it sits at the same depth in the soil that it was during germination. Mist the seedling with water.
Upon transplanting, use potting mix, which is looser. Plants can also be started from a cutting of an existing plant. Cut a tip, about 3" to 5", as long as it's not absolutely new growth. Pinch off any flower buds and remove any large leaves from the lower part of the stem. Dip the stem in rooting hormone and then plant in a contained mixture of two parts sand to one part peat moss. The cutting is ready to transplant when it develops its own roots and begins to anchor itself in the soil.