The Growing Cycle
A hosta year can be divided into 4 periods, that roughly coincide
with our seasons.
It's no a bad practice to keep this growing cycle in mind with almost every activity, like planting, repotting, dividing, feeding, etc.
The hosta is in dormancy. The leaves and all parts above the ground have died back, new growing points have already been formed, but they now are dormant.
Dormancy ends and the hostas emerge again. Usually this starts during the second half of March (in Belgium or Holland). Mainly leaf growth.
The root system expands and rejuvenates. Many cultivars start blooming and setting seed. Often a second flush of leaves is formed, sometimes with different colors than the first flush.
Late cultivars start blooming. The early bloomers have set seed (it takes about 6 weeks from pollination to ripe seeds). The plants build up reserves before they go into dormancy. On most of the plants leaves start yellowing and die. Some species and cultivars keep growing until the first frost.