In my front yard is a mature White Pine that currently looks like it is about to die. The entire tree has a yellow cast to it caused by bundles of 2-year-old needles that have finished up their life cycle, have turned yellow, and are now dropping and blanketing my lawn. If this were a different plant I might be concerned, but because this is an annual occurrence and not a sign of disease or insect problems, I just suffer through it until it has passed and the tree returns to it normal bluish-green color. All evergreens eventually shed their older needles, thankfully, not as dramatically as White Pines.
You would think, living in the “Evergreen State”, that residents would be familiar with this phenomenon, but nary a fall goes by that we don’t get calls about Pines dropping their needles or Western Red Cedars turning brown and shedding theirs. I repeat, in most cases this is a normal process and nothing to be concerned about.
The Morton Arboretum has this to say about seasonal needle drop: “Needles of conifers have varying life spans and do not remain attached indefinitely to the tree. The change can be gradual, or, with some species, quite rapid. In times of drought, needle browning may be particularly noticeable, because more needles are shed in response to environmental stress. White Pines show the most dramatic needle drop change. Spruce and Fir needles also turn yellow and drop, but the change is usually less noticeable because their older needles are thinned progressively, making the process more gradual than in Pines. Arborvitae sheds branchlets rather than needles which usually turn brown as they age, yet remain on the tree for quite some time before falling.”
Now, there is a caveat to this of course, and that is simply that if all of this yellowing or browning is happening on the tips of the branches rather than towards the interior, then chances are your evergreen is experiencing problems - which could be insects or diseases or more likely drainage issues. Either way, action will need to be taken before the tree succumbs and dies.
We like to think that planting evergreen shrubs and trees will save us from raking copious quantities of leaves in the fall, but the truth is, that while evergreens are never out of leaf like deciduous plants, they are constantly shedding leaves (needles if you prefer), which left unattended, will pile up underneath the plant. This is not necessarily a bad thing as all those needles will suppress weed growth and insulate the soil. But they will also repel moisture from penetrating the soil, which can present its own challenges. Also, in the case of densely growing evergreens like arborvitae hedges, all those needles tend to collect inside the branching structure and can present a fire hazard. I recommend occasionally cleaning out the insides of hedges with a strong blast of water to guard against potential fire (and sometimes disease) issues. If you decide to rake up all those years of needles on the ground, be sure and replace them with some bark mulch to protect the root system.
So, the upshot here is that evergreen needle drop is part of a normal process and as long as the tips of our evergreens look healthy then everything should be hunky-dory. If, on the other hand, your evergreens are looking a bit “dull” or lacking luster and the tips are brown, then by all means you should be concerned and consult with a Certified Professional Horticulturist (which you can usually find at your local garden center). Hope this helps!
