My four dwarf Alberta spruce are a perfect height but are getting too wide for my garden. I've been told they cannot be trimmed to make them skinnier. Is that true?
It sounds as though dwarf Alberta spruce wasn't the best choice for your garden. The trees can get rather wide (up to 8 feet), and it is difficult to keep them narrow. Trim back the new growth that appears on the side branches each year. By doing this, you may keep them from getting much wider than they are now.
Avoid pruning back into old wood that has no green needles on it. Such a severe cutback often disfigures the conical shape of the tree. If that doesn't sound as though it will work for you, transplant the spruces somewhere else in your yard where they will have room to grow as large as they need to. Select another, smaller tree for your garden-one with a mature size that fits the site.