November 15, 2015
Highway trees project a continuation of 401 planting
Dr. Darby McGrath, Vineland’s Research Scientist, Nursery and Landscape, is joined by her assistants with the highway trees project, Erin Agro, Research Technician, Horticultural Production Systems, and Jason Henry, Research Technician, Nursery and Landscape.
Vineland Research and Innovation Centre (Vineland) is continuing the task to develop guidelines to sustain healthy trees along highways.

Dr. Darby McGrath, Research Scientist, Nursery and Landscape, at Vineland, says  “In preliminary results from the first planting season, we found not all trees classified as urban-tolerant are suitable for planting in unmaintained sites.” She points out that nursery stock size is also an important consideration for transplant survival, particularly in areas where weed competition is high and moisture content is variable. “The team also discovered shrubs provide important benefits to trees in roadside ecosystems because they are able to acclimate to challenging environments and help surrounding trees adapt to harsh site conditions.”

Vineland has designed two experimental test planting sites, one at its Vineland campus and the other at Fifty Rd. on the northbound side of the QEW in Niagara.

Back in 2010, Landscape Ontario, Vineland and the Ministry of Transportation planted 7,000 trees at the intersections of the 401 and 427, near Pearson Airport, and 401 and Allen Expressway at Yorkdale Mall.  Trees were supplied by Vineland, Braun Nurseries, Willowbrook Nurseries and Sheridan Nurseries.

Dr. McGrath says her team will be accessing those sites this fall to check on the survival of the trees planted at the Toronto sites. She says since those sites were planted, the research team has found there are a number of factors that determine the success of trees in difficult environments along highways.

“There are many types of trees available for planting in urban environments, however, planting near multi-lane highways where follow-up care for trees is limited, means that trees need to be robust to overcome the transplant and establishment periods,” says Dr. McGrath.

At each of the Niagara sites, eight different tree species, including Autumn Blaze Freeman maple, Kentucky coffeetree, Cully river birch, Triumph elm, Glenleven linden, Common hackberry, trembling aspen and silver maple have been planted. Three types of shrubs have also been planted at the sites. These include grey dogwood, nannyberry and common ninebark.

The team selected the trees from the urban-tolerant trees project team, led by Thelma Kessel of Lacewing Horticulture, which included Sean Fox, assistant manager, University of Guelph Arboretum; Jennifer Llewellyn, OMAFRA nursery crops specialist; and Dr. Glen Lumis, professor emeritus, University of Guelph. The list of trees from that project may be found at

“Vineland will continue to monitor the sites for tree survival and growth over the next two seasons. The research will also be expanded next year to examine the benefits of mixed plantings for improving plant growth, water and nutrient retention. The team will at the same time investigate whether mixed plantings can offer trees buffering from root shading, wind and salt spray damage,” says Dr. McGrath.

The Vineland team expects to rewrite specs for trees planted along busy highways. Those specs will be ongoing until the funding ends in 2018. Dr. McGrath expects that the study and process to change provincial and municipal planting specs will carry on past 2018. The challenges in the study are not just horticulture challenges,” says Dr. McGrath.  There is work to do with changing how governments deal with soil and planting requirements.

This research project is part of Vineland’s Greening the Canadian Landscape. The program has expanded across Canada, and includes a number of partners. Several large Canadian cities are part of that partnership, along with a number of provincial governments.

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.
Dr. McGrath says municipalities interested in the project may contact her at 905-562-0320, ext. 766, or