The time of year for gardening is the perfect time to prune your garden, as many shrubs in the backyard are overgrown. Overgrown plants have little value in your garden and if they do not respond well to pruning, you may have an opportunity to replace them with new plants. The dormant season is the best time for this work, as healthy plants will respond with lots of new growth. The senior director at the Chicago Botanic Garden, Tim Johnson, suggests that pruning plants that have become overgrown aggressively is a good strategy. He recommends removing large stems at ground level, especially if they have formed mature bark, and using a small folding hand saw to remove the remaining stems to minimize damage to any remaining young stems. If your shrubs do not have young stems, cut back the thick old stems to about 2 feet, just above the point where there is a young stem, resulting in new growth from the old stems and a spindly growth. It's OK to be less aggressive when pruning most evergreen shrubs, but be cautious about aggressive pruning.