We are approaching the most important time for vigorous growth of our trees and shrubs. The growth will not come this year. It will come next year.

Don’t wait until next spring to think about the backbone of our landscape. Trees and shrubs need to be fertilized very soon to help them grow steeply after winter.

Jerry Somalski, owner of Bay Landscaping in Essexville, MI, calls the group of trees, leafy shrubs, flowering shrubs and evergreens “woody ornamentals.” In his world, a woody ornamental is any landscape plant that doesn’t die back to the ground in the winter.

Somalski says it’s more important to fertilize now than in the spring. While you may feel like your trees and shrubs are done growing, they’re actually storing up energy for next year. Fertilizing now in early spring gives our trees a big boost.

Somalski also warns that very heavy pruning in winter will cause the plant to need a lot of stored energy in the spring.

The best time to fertilize trees and shrubs, according to Somalski, is September 15 to October 15. He says we can still fertilize these ornamental woody plants between October 15 and November 15. After November 15, fertilizing may be too late and not be absorbed by the plants’ roots. There is also the danger that frozen ground will cause fertilizer to run off into a sewer, drainage ditch or stream. He warns us that fertilizer on frozen ground will eventually make its way into a Great Lake and is not good at all for our beautiful Michigan waterways.

A fertilizer bag contains three numbers that make up the most important nutrients in a fertilizer: nitrogen, phosphorus and potassium. These three most important nutrients are the three numbers on the bag. But don’t worry about finding the perfect fertilizer. “At the end of the day, fertilizing is always good this time of year,” says Somalski. Jerry advises us to use a fertilizer where the three numbers are in a 3-1-2 ratio. That means the first number is about three times higher than the middle number and the third number is twice the middle number. His landscaping company uses a 15-2-8 fertilizer.

You’ll have to do a little searching in your area and probably go to a landscaping company to find this fertilizer. Lawn fertilizers in Michigan are now all phosphorus-free, meaning the median level is zero.

How much fertilizer? He tries to keep it simple for us. Apply a half pound of product per inch of trunk to the tree. He says we should only try to fertilize trees with a trunk diameter of up to six inches. As the tree gets larger, ask an arborist to help you fertilize. Larger trees should be fertilized on their own. If the large tree appears to have a health problem, fertilizing might help. The first step would be for an arborist to identify the problem.

To clarify where to apply fertilizer, Somalski wants us to imagine a doughnut on the ground. The trunk would sit in the doughnut hole. The doughnut hole would actually extend two feet from the trunk. In other words, don’t fertilize right at the trunk and two feet out. Then apply fertilizer in a circle that extends four feet from the doughnut hole. Imagine fertilizing the doughnut. He says we don’t want to fertilize up to the “drip line,” which is basically the ends of the branches. Concentrate fertilizer where the most tree roots are closer to the tree or shrub.

Commercial fertilizers that are specifically for evergreens may also have the required analysis for all of your trees and shrubs. He hopes we can get a fertilizer that is suitable for all of our ornamental trees.

Is it worth fertilizing larger trees and shrubs? “Sure, after three years a plant can be up to 50 percent larger than an unfertilized tree,” says Somalski.

We have a few weeks to prepare the fertilizer we want to use on our ornamental trees, then it’s time to apply the fertilizer that will lead to growth next spring.