Hello,

Landscape trees and shrubs in Michigan usually do not need extensive fertilization to maintain good growth and color. Read more here: https://www.canr.msu.edu/news/landscape_tree_and_shrub_fertilization_guide_now_available

And here: https://www.canr.msu.edu/uploads/files/Nutrition_and_fertilization_BertCreggfinal.pdf

And here: https://extension.unh.edu/sites/default/files/migrated_unmanaged_files/Resource000590_Rep612.pdf

Most established trees in the landscape do not require fertilizing unless it is obvious that something is wrong with it. A soil analysis will help establish whether any nutrients are missing. To learn how to obtain a testing kit, go to: https://shop.msu.edu/products/bulletin-e3154

Until the trees show some sign of stress with a yellowing of leaves, fertilizing should be avoided. If it is necessary and a soil test shows that nutrients are missing in the soil, the soil test will recommend the proper amount of fertilizer to be added.

Usually, fertilizing would take place once a year, in late winter or early spring. It is avoided later in the season because it may stimulate new growth which would be detrimental to the health of the tree as it goes into dormancy.

You can test for spider mites by shaking a branch over a white paper. The mites will fall out and are easy to identify. The easiest method of removing them is to hit the branch or shrub with a hard spray of water from the hose.

Thank you for contacting Ask Extension.