All evergreens go through a natural shedding of the oldest (inner) foliage each fall. Each species of evergreens tend to keep its needles for a defined length of time. Cycles, or patterns, of needle drop develop for each species, although variation exists from tree to tree and from year to year.Several factors influence the how extensive the needle drop will be. The lifespan of the needle varies with the kind of tree. How severely your tree sheds this fall depends on what type of growing season the plant had when its needles were formed, many years ago.
Average Life Span of Needles
Needle Life Span
|Arborvitae||Thuja occidentalis||2–4 Years|
|Douglas Fir||Pseudotsuga menziesii||5–7 Years|
|Hemlock||Tsuga canadensis||5–7 Years|
|Austrian Pine||Pinus nigra||3–4 Years|
|Mugo Pine||Pinus mugo||5 or More Years|
|Ponderosa Pine||Pinus ponderosa||3 Years|
|Scotch Pine||Pinus sylvertris||3 Years|
|Swiss Stone Pine||Pinus cembra||4–5 Years|
|White Pine||Pinus strobes||2–3 Years|
Remember, these numbers are average life spans. Needle drop is also affected by nutrition, rainfall, disease and various other stresses.
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Select source information provided by the University of Minnesota Extension, www.extension.umn.edu.
Last Updated: March 2012