Native Holly (Ilex opaca) makes an attractive hedge, but I would hardly recommend its use for enclosing a garden in northern latitudes. If you have some position that is sheltered it would repay you to try it, for it is particularly beautiful in Winter. Spruce is too coarse and clumsy for a hedge except on a very large scale, and it will not do well near other trees; it is more valuable for a screen or wind-break. A Spruce hedge does not blend well with a garden of old-fashioned flowers.