Now is the perfect time for planting a new tree, whether for shade, fruit, landscaping or just plain beauty. Plus, trees produce clean oxygen and absorb climate-changing carbon dioxide.
When you're ready to plant a tree, key elements for success are choose a good species for the site, dig a hole that's appropriate in width and depth, and provide adequate water.
The garden centers will probably advise that you buy fertilizer and even pesticides for your trees, too. But before you apply either, consider expert advice that suggests less is truly more. Ohio State University researcher Dan Herms, who has a doctorate in entomology, studies the interactions between trees and pesticides and fertilizers, examining both intended and secondary effects. Here, Herms explains why less fertilizer and less pesticide equals healthier, happier trees.
Q: Ideally, what is the most effective way to plant and grow a healthy tree?
A: In my opinion, there are three critical elements. The first is to choose a tree that's adapted to the site in terms of your soil pH, the light environment, the local precipitation patterns and so forth. In many cases it's going to be one that's native to the area ? but not always ? because urban environments are so dramatically altered that they don't necessarily resemble the local forest.
Second, plant carefully. A lot of problems are associated with improper planting techniques. Many times trees are planted too deeply and the hole isn't wide enough ? it should be much wider than the rootball. The critical thing is water, especially with newly transplanted trees. Even for an established tree, I think the most important thing you can do for fostering health is watering during droughts. And in my experience, trees do just fine without fertilization. We've never fertilized any of our trees and the vast majority of trees out there have never been fertilized.
Q: Homeowners are often told to apply
fertilizers to newly planted trees to promote their growth. You
advise against this ? why?
A: Fertilization suppresses the natural defense systems. There's really strong evidence that the faster a tree grows, the lower the level of its defenses. Fertilization also makes trees more nutritious to insects. So insects feeding on fertilized trees grow faster, have higher survival rates, and lay more eggs. We found the same in our research of disease. Fertilization weakens the tree's defense response to diseases. Fertilization can even make the trees more susceptible to drought stress by decreasing the root/shoot ratio (by stimulating leaf growth, proportionally, more than root growth).
For tree planting tips and instructions, check out ' Home Landscaping,' from Mother Earth News magazine. The National Arbor Day Foundation will help you discover a wide selection of tree varieties, their specific growing needs and which trees grow best where.