Research Articles

     As we give advice to customers who ask for our expertise, we often are greeted with unbelief in the suggestions we give. As these suggestions are based off of evidence based results, we’ve decided to post links to those results and the practices they recommend. This page will continue to be updated with the most recent best practices when it comes to planting and caring for trees and shrubs. 

Amending Soil

“This outdated practice is still required in the specifications of architects, landscapers, and other groups associated with landscape installation. It is still recommended by garden centers and gardening articles. And there is a multi-million dollar soil amendment industry that has little interest in debunking this myth. As responsible green industry professionals, we need to recognize and avoid non-sustainable management practices.”  – Linda Chalker-Scott, Ph.D. “The Myth of Soil Amendments”    Link:

“Fill the hole with the original native soil – this is the soil the tree must ultimately move its roots into to survive. Large rocks can be removed when backfilling. Up to 25% by volume of composted organic matter can be mixed in with the backfill soil if it has a very high clay content and is difficult to work, but in such cases till the soil just outside the root ball 8 to 12 inches deep and several feet wide after planting to ensure good root growth. Otherwise use no other soil amendments. Polyacrylamide gels (water absorbing polymers) added to the backfill at planting time have been shown to have no significant effect on tree survival or growth.” – Kuhns, Michael R. and Rupp, Larry, “Selecting and Planting Landscape Trees” (2000).   Link:

“The American Forestry Association has drawn up new guidelines for how to plant a tree, and unless you’ve been reading a lot of research information lately, you will
find many surprises such as don’t dig a planting pit and don’t add soil amendments to the planting hole.” – Akbari, Hashem. “Cooling our communities. A guidebook on tree planting and light-colored surfacing.” (2009).    Link:

Disturbing The Rootball

“Though gentle handling of roots is good advice when transplanting seedlings, especially annual flowers and vegetables, woody perennials, shrubs, and trees all benefit from a more vigorous approach. There are several reasons for this, and surprisingly some of the harshest techniques result in the healthiest plants.”  – Linda Chalker-Scott, Ph.D. “The Myth of Fragile Roots”   Link:

“If container-grown plant materials are rootbound (roots already circling within pots) at transplanting, roots may continue to spiral within planting holes. To prevent encircling, cut or disturb roots by pulling them apart. Alternatively, use a sharp knife to make vertical cuts one inch deep at 4 to 6 different locations around root balls. If plants are not root bound, it is not necessary to disturb roots.” – Nicole Ward Gauthier & Cheryl Kaiser, Plant Pathology Mike Klahr, Horticulture Extension Agent   Link:

Vitamin B-1

“Vitamin B-1, aka thiamine, does not reduce transplant shock or stimulate new root growth on plants outside the laboratory”  –  Linda Chalker-Scott, Ph.D. “The Myth of Vitamin Stimulants”   Link:

“Vitamin B1 (thiamine) is one product that makes claims that cannot be supported by science. So, why do sellers of vitamin B1 products say they “prevent transplant shock” and “stimulate new root growth” if these claims are not true?” – Jeff Schalau, Agent, Agriculture & Natural Resources of University of Arizona Cooperative Extension, Yavapai County   Link:

“Supplemental watering is the single most important method for preventing transplant shock.” – Nicole Ward Gauthier & Cheryl Kaiser, Plant Pathology Mike Klahr, Horticulture Extension Agent   Link: