Here is an excerpt from a Bob Solberg article on hosta physiology.
I understand from this and other things I've read that root growth actually follows leaf development---leaves develop in the spring and then also after blooming and the roots follow to support the leaves. Entire article is at
http://www.globalgardens.com/hostap-a.html
"With the arrival of spring, the buds begin to swell and the hosta unfurls its first set of leaves in the spring. There are usually three leaves, as this is characteristic of the lily family, of which it is a member. The size of the leaf is dependent on what happened last fall, before it went dormant. More on this later. About three weeks after the leaves unfurl, the roots will begin to grow. New roots will be formed, and the tips of the old roots will turn white and begin to grow. Depending on the climate and what type of hosta, another flush of growth can occur again later in the spring. New leaves will be formed from this years growth, followed by new roots in a few weeks.
Sometime in the summer, the plant will switch gears and go from a vegetative phase to reproductive. Flower stalks will form and bloom. A show of hands was taken to show how many remove flower stalks as they appear. No one does, probably because it is so much trouble. Actually, it serves little purpose, as the flower was already formed the prior year. It is not the flower that takes strength from the plant; it is during seed production that the hosta expends a lot of energy and nutrients. In fact many people remove the flower stalk after flowering but before seed set.
After the hosta has bloomed and the heat of summer has moderated, our idealized hosta will send up another flush of growth. This usually occurs five to six weeks before the last frost date. After this final flush of growth, the hosta will again shift gears and get ready for dormancy.
Now we have examined the life cycle of our generalized hosta. But why is it important? Because it tells us when the best times are to divide and fertilize.
til dormancy... If a hosta is a late bloomer, say anything plantaginea, there is less time between blooming and dormancy, do they generally develop less roots on average, than say an undulata which blooms early... I noticed this year digging up some undulata albos they had way more roots than any honeybells that I was digging up...
