Answer: The planting distance depends on the effect you are trying to achieve. If you are using them as a formal hedge, plant them about two thirds as far apart as their expected mature width. This will give you a solid line but allow the plants some space for their roots. If you want to see air between them for a less formal look, allow a bit more than their expected mature width. Each specific variety has its own expected mature size.
All plants grow better when air and sun can reach all sides of the plant. If you plant against a wall, they will lean outward from the wall in search of more light. They are sometimes used at the corners of foundation plantings where the sun tends to reach more of the circumference, but as a general rule I would not recommend planting them along a building.
Q&A Library Searching Tips