I am certainly not one of the rose experts here, but as a farmer I have been taught that the top mass and roots on pasture grass (or any plant) must match. We are, therefore warned not to graze pastures too short or the plants will reduce their roots to match. Those little roses grew all those leaves and branches so, it seems to me, they must have the roots to support them. It their tops are cut off, might it not cause them to reduce their roots to match?
