The following question was sent to the P&PDL diagnosticians here at Purdue University:
Question: I have a question about Colorado Spruce trees. We are thinking of buying some trees from a man who has grown them from acorns. He has grown probably about a hundred of them within a fairly small space (maybe 20' x 20' - I'm guessing). They are all now between 6-10' tall and look quite healthy and green except that they do not have any branches on the lower third (or so) of the tree. He tells us that this is because they have been grown so close together but once we plant them properly spaced, the lower branches will come. These trees are a really good price and we would like to buy about 20. He seems to know his stuff - he has created himself an absolutely beautiful 3 acre yard of spruce and pine trees - all from acorns. Is the information he is telling us true?
Answer: In response to your question about the spruce, unfortunately, the gentleman was wrong about the trees growing new branches. Conifers often grow close together in nature. The bottom branches self-prune due to lack of light. This is exactly what is happening with the trees in this man's yard. Deciduous trees have dormant buds along their branches and trunk. Often if a tree that has grown in the shade is exposed to the light, branches will occur. However, conifers don't function in the same way.
You see that difference between conifers and deciduous in another way as well. If you cut a deciduous tree off it will often sprout from the stump. Conifers will not do that. So the gentleman should have placed his trees 6 feet apart when they were being grown from seed and he would have lots to sell now. By the way spruce grow from pine cone seeds and not acorns.
-Rita McKenzie, Urban Forester (5/7/98)