learning about our plants: Buxus and Centaurea

I discovered today that the little evergreen shrubs in our front yard is called Boxwood or buxus sempervirens. I've noticed they suffered a lot from the frost this winter, so I think next winter, until they are larger, we should cover them in burlap or something like that to protect them from the cold. Appearantly they are slow growing shrubs, which is to bad because a whole bunch of the small branches broke off, and they were small to begin with. We will see what happens there. They are usually planted in shade or partial shade, ours are in direct sun, so that means they need to be water regularly. They also need (liquid) fertilizer every 2-3 weeks according to several websites, and pruning is best done spring/early summer and no later than august. Overall it sounds like a shrub that requires a lot of attention. I think landscapers put these guys in as a selling feature to spruce up the look of the front yard. we moved three of them from where they originally were to below the window, and I am not sure if we shouldnt do the same with the ones still remaining around the lamppost. I like the way they look there, but snow get's piled high on top of them over the winter and I am not sure if they can survive another winter like we had this year.
One of the books I picked up at the library also provides information about some of the plants currently in our garden. It is a great book called Care Free plants, A guide to growing the 200 hardiest low-mainentance long-living beauties in Canada... Wow, what a mouth full, but it is nice anyway. So I discovered the name of a couple of flowers which we assumed were related but had never seen before until last year. They are perennials called centaurea (aka knapweed). In the back yard we mainly have Mountain Bluet, while the front yard mainly has Cornflowers. They are originally european wildflowers. In order to keep the flowers blooming all summer long, dead-heading or cutting for bouquets is encouraged. This will stimulate production of more flowers. Plants should be dug up and divided every 2 or 3 years in early spring or fall and replanted at approximately the same depth to keep the plants healthy. Mountain bluet can spread through underground roots as well as through seed.