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