Trees that retain their leaves all winter

Every year we receive several calls from clients asking why their Oak, Hornbeam or Beech trees retain their dried-out leaves over the winter. These dried out leaves are referred to as ‘marcescent’ leaves. There are varying opinions as to why this occurs.

Here is what happens.  Early cold Fall weather or frost seems to encourage some trees to hold onto their dried-out Fall leaves. For some trees, especially certain Oaks, clients mention that a particular tree seems to experience this every year.

For most trees, cells release enzymes that unglue the leaf from the tree in the Fall allowing them to fall to the ground. But early cold or frost can interfere with the process on these previously mentioned varieties of trees. Marcescent leaves are more common on smaller trees or on the lower branches of larger trees.

Some believe that this process occurs with trees that are lacking proper nutrients. But we at Tree Green do not believe this to be the case. Why? Because we have clients whose trees we have been feeding every year for 20 to 35 years still experience this situation. We know that there is no possibility that these trees are lacking nutrients when you consider the suspension of rich minerals, nutrients and amino acids that our root fertilization process provides.

When the new tree buds form and begin to swell in the Spring, they will push off last seasons dried leaves as you have experienced in the past.  Until that process occurs don’t worry about your tree at all. Just enjoy those rustling brown leaves that seem to be ‘waving’ to us throughout the Winter.

A Rough Spring Ahead?

We’ve recently noticed that certain types of flowering trees and shrubs have their 2016 flower buds swelling, and in a few instances, actually opening this December! Why? The trees are confused.

The abnormally warm November and December is tricking certain Magnolia, Crab Apple and potentially other plants into thinking they should be flowering. We’ve seen this happen before. What may unfortunately occur is this…

When the flower buds are tricked into swelling ahead of schedule, whether they actually open into flowers or not, they may be damaged by the inevitable cold winter which will surely follow. It may not be as cold as usual due to El Nino, but it will be cold enough to burn and dry out the buds. This means that your tree may not flower at all in 2016, or the flowering may be sparse or weak.

We already know that we will be receiving calls next spring where the messages will be as follows….

”You sprayed our tree last year and now it won’t flower”. Rest assured that if this happens to your tree, it has nothing to do with any applications. Mother Nature is the guilty party.

This situation can also occur when we have an unusually warm January or February. Those flower buds swell early, and then if we get night time freezing temperatures in March, ‘Winter Burn‘ sets in and the buds suffer from the same negative effect.

A lot will depend on the exact varieties of trees that are involved within each species, not to mention things like soil moisture as well as directional exposure in relation to your house or other mature plantings, which may or may not protect them from cold winter winds. Only time will tell as to whether or not your trees will be affected next spring.

Harsh Effects of a Dry Fall

hemlock pine with winter burn

hemlock pine with winter burn

It’s been a dry Fall in the western suburbs, so here are some things you should be aware of:

Other than that 3 inch rainfall we received about four weeks ago, it’s been pretty dry since June. Much of that rain quickly ran off the ground and into the sewers as the ground was so dry the rain simply sheeted away.  Hopefully we will soon get into a Fall weather pattern that will bring much needed moisture to the trees and shrubs prior to Winter. But what if it stays relatively dry?

If your conifers, (pine or evergreen trees and shrubs) go into the Winter without sufficient moisture stored inside them they might suffer severe needle browning either during the Winter or early next Spring. This situation, called ‘Winter Burn‘, could cause certain sections of the tree, or the entire tree, to suffer severe browning. If the tree or shrub is really low on moisture a severely cold, windy Winter could even kill it.

White Pine, Spruce, Scotch and Austrian Pine, Hemlocks, Mugho Pine and Arborvitae are just a few examples of conifers that should be watered.

Don’t worry too much about the really large older trees as they are too big to efficiently water. Also, older trees have a more expansive and dense root system allowing more water storage capacity. Do pay particular attention to your younger trees however. Younger trees and shrubs, especially those planted within the last 5 years or so, should be given special watering attention as their root systems will not be as fully developed.
Conifers need to have plenty of stored water in their roots and needles because they do not go completely dormant in the Winter like deciduous (leafy) trees and shrubs do. If they go into the Winter without sufficient moisture the plant suffers.

euonymous with winter burn

euonymus with winter burn

In addition, shrubs that retain their leaves all Winter long such as Boxwoods, Euonymus, Azalea’s and Rhododendron should also be thoroughly watered.

Your neighbors might think you are a little crazy if they see your sprinklers running in November but if they ask, share this knowledge with them. You will be doing them a favor. For the record, watering can be done right up until December as trees and shrubs continue absorbing water and nutrients until the ground freezes.

If you have an underground automatic watering system that is due to be winterized find out when winterization is due to happen. Water everything thoroughly just prior to the system being shut down for the Winter. If it has already been shut down, or will be soon, pull out the old fashioned hose and sprinkler.

For tips on proper watering here is a direct link to our website covering that topic.