Garden with Insight v1.0 Help: germination
Germination is the expansion of a seed through absorption (imbibing) of water and its growth into
a seedling. The seedling leaves, which are already in the seed, expand
and emerge from the soil to begin the photosynthesis that will help the plant grow other leaves.
In this simulation germination depends on two factors: soil temperature and soil moisture. Soil
temperature affects seed germination in the same way that air temperature later affects plant growth: by
affecting heat unit accumulation. The number of degrees Centigrade
the soil temperature is above the best temperature for germination (a parameter) is accumulated until a threshold is reached. On the day the heat
unit threshold is reached, the soil water is checked; if it is above the amount needed (another parameter),
the seed germinates. Of course it is not very realistic to check the soil
moisture on only one day, since the seed imbibes water over a longer period of time, but it is assumed the
soil moisture is buffered enough to be similar on other days.
There is a variety of special germination requirements in nature. Some seeds cannot germinate until their
seed coats have been cracked by freezing and thawing. Some must be scorched in a fire. We don't simulate
any of these mechanisms here; germination is assumed to depend only on temperature and moisture.
How it works: