Ask Mr. Smarty Plants

We went looking for a "Blue Bruce" pine, but could not locate one. We did, however, find Picea pungens (blue spruce), which is a native of North America. It is mostly found in Colorado, but since it has a "Christmas tree" shape, it is widely sold in the nursery trade. The blue spruce is in the genus Picea, and one of about 35 species of coniferous evergreen trees in the family Pinacea. There is a lot of confusion about which trees are really pines, and which are firs or spruces. Read this Gardenline webpage on Fir, Pine, or Spruce - Which do I have? In terms of your question, it really doesn't matter a whole lot what it is, as they all share the same characteristics of creating acidity in the soil beneath them.

So, the problem is not the strength of the plant that goes beneath the tree.The problem you are having is due to the acidity of the soil. The acid-loving plants are rhododendrons, including azaleas, blueberries, blackberries and hydrangeas, as well as many types of evergreens and conifers. All of these are considered moist woodland plants, but they all require some sun. Leaf drop from deciduous trees, and especially conifers, will raise the acidity in the soil underneath. Really, if you value your tree, and you certainly should, you need to leave it alone, and not try to grow anything until out beyond the drip line of the tree. And don't clean those needles up-the tree needs them for continued nutrition. Here is a page of Images of the blue spruce.