A few weeks ago, I blinked, and a lot of trees changed color.

I blinked again last week and found out it was time to rake leaves.

Fall seemed to come on pretty quickly this year. Maybe it was because I was busy doing other things. The trees knew it was coming, though, and they prepared.

Leaves on the deciduous trees changed color as they drew nitrogen back into the twigs to be used for next year’s growth. Then, those same trees shed their leaves to prevent water loss over the winter.

But what about the evergreens?

I’ve had a lot of emails over the last few weeks about conifers losing needles. In each case, it was the older, inner needles of mature trees. Most people said that they had never seen this before.

I had to break the news to my clients: This is normal, and it’s okay.

Every year, mature conifers shed the older, inner needles from the crown because they’re just not as productive as they used to be. Quite simply, the younger needles near the ends of the branch are getting the sunlight, shading out the older needles.

And this is normal. It happens every year. 

Right now, both my driveway and my pickup are covered in pine needles. Time to get out the leaf blower.

This happens to all conifers – pines, spruce, arborvitae and juniper trees. 

A healthy conifer should have at least three years’ worth of needles on the majority of its branches. Needles sometimes live for seven or eight years before dying. That’s a lot of photosynthesis!

This year, it does seem like needle drop is heavier than usual. I’m guessing that this past summer’s drought is playing a part in that. 

It could also be insect or disease problems, such as spider mites or a needlecast disease, that are making things worse. 

Pest problems can be dealt with. And so can drought.

Watering conifers in the fall is a great way to minimize problems with “winter injury.” I put that term in quotation marks because it’s actually rather vague.

Winter injury shows up in the spring as dead/dying needles, often in no particular pattern around the crown. We usually attribute it to water loss from the needles on those winter days when it’s above freezing and the sun comes out.

We try to prevent that by making sure the trees go into winter being fully hydrated. Just place a hose near the base of the tree and let water trickle slowly into the soil. Move the hose around to cover the entire root system.

Another good thing to do for winter prep is to protect the younger, smaller trees from rabbit damage. Rabbits and other rodents can easily destroy a tree by chewing off its bark during the tough times of winter.

This damage is easily preventable, but I still get emails each spring from people asking what they can do after the fact. At that point, the answer is “remove the tree, and do better next time.” 

It’s a hard lesson to learn. And a harder one to teach!

By Joe Zeleznik, Forester, NDSU Extension