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Question from Shelton Beach, Arco, ID (received 7/7/20) -
I have a windbreak of some 40 mature blue spruce trees, probably 50 feet tall. They are planted in 2 rows. The trees are fairly close together, about 5 feet apart. If I run a drip hose down each side of the row of trees, will that be adequate? Do I need to water around the trunks of the trees?
Answer from Dr. Mike Kuhns, USU Extension Forester and Professor (sent 7/15/20) -
Shelton,
Five feet apart is too close, especially if the rows are also 5 feet apart. They will be competing for water and light especially. Drip irrigation likely will not be adequate. These trees probably need a couple of hundred gallons of water a day each. However you apply the water, it needs to moisten the soil near the trunks and at least put to the edge of the canopies. Besides watering adequately I suggest that you try to figure out a way to remove maybe half of the trees to make the remaining ones healthier. You may not be able to do this though because with the trees being grown so close together for so many years, their canopies will have mutually shaded each other to the point that what is left will not function well as a windbreak.
Good luck.