Generally, the elements needed for growth fall into
two categories: terrestrial (soil and nutrients) and
celestial (air, warmth, moisture). The celestial elements
cannot be completely categorized, however, since air,
warmth, and moisture come from the heavens to
circulate through the soil, and plants can take in air
through their roots as well as through their leaves.
Nutrients can also be borne upon air currents. In fact,
citrus trees take in the important trace mineral zinc more
readily by their leaves than by their roots. See chapter 7
for further information on the parts that other elements
in the plant and animal worlds play—other plants and
insects, for example.
A seed is planted at a depth equal to its thickness.Seed Planting
Be sure to use open-pollinated seeds. They have stood
the test of time, and that is why they are still available