November at The Arb- Winterizing Trees, Upcoming Workshops, Beavers, & More!

There are few things I find more annoying in the garden than planting a new tree or shrub, only to find in spring that it did not make it through the winter. While this is frustrating in the home garden, it is a bit more of an issue at The Arboretum, where we are trying to maintain a diverse collection of woody plants, some of which are rare or endangered, and most of which are grown from wild-sourced seed collected by Arboretum staff. By the time a new tree, shrub, or vine is planted in our collection, it has several years of care and work put into it by our nursery staff. Developing our collections is a lot more work than taking a trip to a garden centre, so it is especially important to us to make sure that we take care of it to the best of our ability. To give our young, sensitive, or rare woody plants the best chance to survive, the horticulture staff have been busy this month preparing them for winter.

Luckily for us, most of our plants can withstand the Canadian winters without any help. For those that do require a bit more assistance to make it through the season, we use a couple of different methods. The challenge of winter is not only the harsh weather, but also animal damage – primarily from rabbits and voles. Most of our collection plants survive just fine in the temperatures of Southern Ontario winters. However, some of the trees and shrubs in our collections and gardens are not quite hardy to our climate or require a little assistance until they are more mature and established. Those specimens that are more sensitive to winter weather get wrapped in burlap to protect them from harsh winds, snow, bright winter sunlight, and fluctuations in temperature. This also provides some protection against animals.
photo of a plant wrapped in burlap next to a rock

photo of a plant wrapped in burlap next to a rock

Some of the shrubs in the Japanese Garden get wrapped in burlap for the winter. Photo by Sadie Campbell.

Rabbits and voles, though they are small animals, can do a lot of damage to woody plants. Rabbits like to eat small stems and buds, which can kill young, newly planted trees and shrubs. Both rabbits and voles will eat the bark around the base of young trees or those with thinner bark. This damage, called girdling, prevents the flow of nutrients, water, and other materials to and from the roots of the tree. This causes the top of the tree to die off. Once the tree or shrub matures and the bark becomes thicker and rougher, it is usually safe from rabbits and voles. Until then, some of our young plants need a bit of extra help to survive the fall and winter, when this damage is most likely to occur.
Colour photo of a young plant with its stem eaten by rabbits

Colour photo of a young plant with its stem eaten by rabbits

colour photo of a young tree that had its bark eaten around the base by voles.

Left: stems and buds on this plant have been clipped off by rabbits. Photo by Sadie Campbell. Right: vole damage on a young tree. Photo courtesy of Rutgers University.

To prevent this damage, we use various types of barriers on our trees and shrubs. Each year we plant hundreds of young woody plants in the spring and fall as part of our Wall-Custance Memorial Forest restoration program. We finished our fall planting in October, first removing invasive species like buckthorn, before replanting with native species that will provide better food sources and habitat for our native wildlife. To protect our newly planted memorial forest trees and shrubs, we use white spiral tree guards to keep them from being clipped by rabbits. In spring, we will remove the tree guard for the growing season (when food is more abundant for the rabbits). The tree guard is stored, and we can reuse it in the fall. This gives these woody plants the opportunity become established so that they can go on the provide food sources to animals like rabbits without being killed. For the larger trees in our collections and gene banks that need protection, we use wire mesh and fencing to prevent animals from eating them. Fences can also help protect small, young trees in our collection from accidental damage from equipment.

Colour photo of a young tree planted on the edge of a forest, wrapped in a white plastic tree guard.

Colour photo of a young tree planted on the edge of a forest, wrapped in a white plastic tree guard.

Colour photo of the base of a medium-sized tree wrapped in a fine wire mesh.

a young oak tree in a snowy field with a wire fence surrounding it. The wire fence has burlap wrapped around it.

Left: A Memorial Forest planting protected with a tree guard. Centre: A tulip tree in the Gene Bank with its base wrapped in wire mesh. Right: a young oak in the collection surrounded by a wire fence and wrapped in burlap. Photos by Sadie Campbell.

One of the other tools we use to prevent animal damage to our more susceptible plants is a spray-on product made from rehydrated animal blood. If you’ve noticed that some of the trees in our collections are stained brown at the base, this is the reason! While this sounds gruesome, we have found that it is a safe, effective, and organic alternative to other repellents, and lasts for most of the winter without needing to be reapplied. The smell of the product deters animals from eating trees and shrubs. When the weather is right in late October or early November, (above 5 degrees Celsius and dry), we spend a couple of days mixing the product and spraying the plants that need protection. This is a fairly quick and effective way to protect our collections and also works well for larger or multi-stemmed trees and shrubs that would be harder to protect with regular tree guards.

Colour photo of a woman wearing a backpack sprayer, spraying a young tree with blood.

Colour photo of a woman wearing a backpack sprayer, spraying a young tree with blood.

colour photos of young trees in a snowy field. The bottom of the trees are darkened by animal blood spray.

Left: Arb staff member Sarah sprays young trees with animal blood for winter protection. Photo by Sean Fox. Right: young Blue Ash in the gene bank, recently sprayed. Photo by Sadie Campbell

This is just one of the things that keep the horticulture staff busy in fall. And with over 900 Memorial Forest plantings to protect, along with the trees and shrubs in our collections, we were pretty happy to get this done before the snow hit the ground this year!