Answer: Pruning generally stimulates plant growth, and that decreases plant hardiness; the new growth makes the plant think "spring!" instead of "fall" (time to slow down and harden off). Fertilizer has the same effect. Ideally, you should cease to fertilize plants at least 6 weeks before hard frost. Prune in late winter/early spring, while the plants are still dormant. Most hedge roses are very hardy and should need no protection once they are established. Sounds like yours are off to a good start!
Q&A Library Searching Tips