Is it too late to fertilize trees and shrubs? - mlive.com

Hydrangeas and evergreens in front of a house on November 5, 2024Mark Torregrossa

Our landscape also needs to eat. Should we feed our trees and shrubs or wait until spring?

One expert, Jerry Somalski, owner of Bay Landscaping near Bay City, says we absolutely want to fertilize trees and shrubs right now, if they need it.

Somalski advises to start with the idea of what you want from each particular tree or shrub in your landscape. If you want a tree or shrub to grow faster and larger, then fertilize it. If the tree or shrub is the size you want, don‘t stimulate growth. Eventually even that perfect-sized plant will become bigger, but don’t bring it on yourself faster than needed.

Somalski also believes any freshly-planted tree or shrub would benefit from a feeding of fertilizer now. He says those plants put in the ground in the past few months have roots searching for food. Fertilizer can be applied up to a week before the ground freezes. Jerry cautions we should not fertilize frozen ground. The fertilizer can run off and become water pollution.

Some of us go to the fertilizer aisle and get overwhelmed. Somalski makes it somewhat easier for us. Trees' and shrubs' most-needed element is nitrogen. The amount of nitrogen in a fertilizer is represented by the first number in the three-number analysis.

Somalski says all woody plants, as in trees, shrubs and evergreens, would enjoy a fertilizer with a ratio of 3 or 4 to 1 to 2. The three numbers represent the percentage of nitrogen, phosphorus and potassium in the bag.

All woody plants can feed on the same fertilizer. We don’t have to buy a tree fertilizer and an evergreen fertilizer and an acid-loving blooming shrub fertilizer. We can get one fertilizer and apply it to all of our landscape trees, shrubs and evergreens.

We can usually find a fertilizer that has an analysis of 16-4-8. That analysis would be Somalski’s perfect ratio for a tree and shrub fertilizer.

There should be the words “slow release” somewhere on the bag. This means the nitrogen has a coating on it so it slowly disperses into the soil and gradually becomes available to the plants. Somalski warns the standard 12-12-12 (called triple 12) or 19-19-19 (called triple 19) are both fast-release nitrogen products. The nitrogen will either go up into the air as a vapor or leach through the soil in three weeks. No additional food will be available to the plants after three weeks. Slow-release fertilizer will be gradually available to plants as they need it, probably lasting a few months. The slow release fertilizer may even still be feeding your trees and shrubs in early spring.

Most fertilizer bags have directions on how much to apply. Jerry gives us a general rule. If the fertilizer is around a 16% to 18% nitrogen, apply one pound of fertilizer for each inch of tree trunk width. For each inch of trunk spread the fertilizer out 2 feet of diameter centered on the trunk. For example, a one-inch trunk would get one pound of fertilizer in a circle two feet wide. A 3-inch trunk would get three pounds of fertilizer in a 6-foot wide circle.

If you can‘t find the perfect analysis of fertilizer, Somalski says the fast feeding 19-19-19 will still do. It’s just not ideal.

If you don’t have time and miss fertilizing your trees and shrubs now, April is a good time to use the same fertilizer at the same rate.

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