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.
Seed Starting: Preparing the Potting Mix Make sure the potting mix is not lumpy. Â© Marie Iannotti Loosen and dampen the potting mix before you put it into your seed starting containers. It is easier to get a uniform level of moisture if you do it this way. Dampen the mix to the consistency of a rung-out sponge. It should be wet, but not dripping, with no dry lumps. There are many good potting mixes available.