What a good seed looks like
Viable
Mature seed is usually dark tan to dark brown
Skip
Light tan, green, or cracked seed is a poor bet
Sleep
The embryo sits in suspended animation until water arrives
Store
Age and temperature change how many days the shell takes to open
Hormones that start the clock
Trio
Water triggers auxin, cytokinin, and gibberellin inside the shell
Auxin
Found in root and shoot tips. It orders new growth and holds lower branches back
Cytokinin
Pushes side growth and cell division
Gibberellin
Directs stem and leaf expansion. Together the three open germination
Root, then shoot
Breakout
The root tip usually splits the shell in one to five days
Seed lunch
Early roots still live on the food packed with the embryo
Gravity
Roots turn down and the shoot turns up once the plant can sense orientation
Light
After the shoot clears the medium, growth follows the brightest source
Cotyledons and first true leaves
Embryo leaves
A pair of cotyledons unfolds, sometimes still wearing bits of shell
First sugar
Those cotyledons start photosynthesis as soon as they face the light
Apical meristem
The growing tip appears between the cotyledons and becomes the main shoot
True leaves
The first true pair follows, then three-blade and five-blade sets as the seedling builds