In the formal language of economics, X and Y are substitutes if the demand for X increases when the price of Y increases, or a positive cross elasticity of demand.
Potting mix is the material that goes into a garden pot before you put seeds and plants into it. 1  It keeps the plant in place. 2  It holds water for the plantâs roots to soak up.  It contains nutrients that feed the plant.
Seeds to seedlings. 1. Fill 4-inch pots to just below the rim with a light, porous seed-starting or potting mix. (You can make your own mix by combining 1 part each of peat moss, vermiculite, and perlite.) Moisten the mix, and let it drain.Scatter seeds thinly over the surface.. Fill 4-inch pots to just below the rim with a light, porous seed-starting or potting mix. (You can make your own mix by combining 1 part each of peat moss, vermiculite, and perlite.) Moisten the mix, and let it drain.