The calendar shows it is the first of August, but many of our landscape plants are looking like it is the first of October.

The robust green of summer growth is giving way to hues of lime green, yellow and red. We have not slipped into a gardening time warp where Mother Nature has lost track of time. The change in colors is because of the change in weather. If your trees and shrubs are red and yellow, here is why and what you can do about it:

The normal green color of plant foliage is produced by chlorophyll. It is responsible for capturing energy from the sun and converting it into sugar and oxygen. In the fall, other pigments begin to emerge when the green chlorophyll begins to break down. This year, however, the process has started early, but this does not mean that fall is on the way.

Chlorosis or yellowing of plant leaves occurs this time of year on trees growing in high-pH soils. The element iron becomes unavailable causing interveinal chlorosis. However, this year we have received so much rain that plants are unable to take up other nutrients needed to maintain their healthy green color. Root systems are shutting down and not absorbing nitrogen, an important nutrient needed for good green color. The result is yellowing of the leaves. Fortunately, chlorosis due to wet soils will correct itself if and when the soil drys out. Plants should regain their color when we return to dryer conditions.

On the other hand, chloris due to a lack of iron in the soil needs to be addressed differently. Iron is an important building block for chlorophyl. However, when trees are stressed, the roots have been damaged or the soil pH rises above 7.2, they are not always able to use the iron that is in the soil. The result is iron chlorosis. Showing up mostly in pin oaks and sweetgum trees, it also can be a problem in silver maple, baldcypress, crabapple, white pine, elm, London planetree, cottonwood, walnut, sugar maple, Eastern redcedar, Bradford pear and willow. Leaves turn a pale green to yellow color while the leaf veins remain a darker green. If uncorrected, twigs and eventually whole branches can die. Affected leaves may be found on the entire tree, on one side or be limited to individual branches. Correcting iron chlorosis begins with adding iron to the plant. This can be by foliar application, soil treatment or trunk injection.

There is a difference between iron chlorosis and yellowing of the leaves due to excessive soil moisture. The first needs to be dealt with, the second there is nothing we can do to stop.

But what about the red? It seems the maples, burning bush, rough leaved dogwood and many other landscape plants are turning red. Again, it is a response to the weather. The red pigment, called anthocyanin, is produced as a response to stress.

What does this mean long term for the plants?

Wait and see. It is doubtful the plants will produce new leaves this late in the season. Therefore they will have to live on stored energy from now until next spring. For now, there is little you can do other than hope for the best.