Dig into fall with a garden party
“We planted a plant at the plant.” Interpretation: We put a botanical species in the ground at the factory.
The English language can be confusing, yet some thoughts are not hard to express, such as: “Autumn is for planting.” The fall season arrives this Wednesday, Sept. 22, and it’s the second, or autumnal, equinox of the year after the spring — or vernal — equinox. Summer and winter seasons start with a solstice.
Plants know all of this. Their calendar is set by the length of a day and it is engineered into their DNA. Therefore, a lilac that normally flowers in May will sometimes produce flowers in late September when the day length is about the same as their spring flowering period. Their natural system for telling time is not foolproof.
Truth is, these are the best days of year, bar none, to celebrate in your garden by doing some planting. As the days shorten and temperatures adjust downwards, the soil holds an abundance of warmth accumulated in the summer which encourages roots of winter-hardy trees, shrubs and perennials to develop even while the top portion of the plant is finished growing for this year. The new roots support new growth come spring, which is why a fall-planted tree, for example, will often outgrow a spring-planted tree of the same size and species.
Coincidentally, the arrival of fall on Wednesday coincides with National Tree Day here in Canada. Not only is it one of the best days of the year to plant, but it is also recognized through a federal Act of Parliament as the day of the year to acknowledge and celebrate the role that trees play in our lives.
Trees sequester carbon and produce oxygen, and perform many other useful functions. While we spend our days on other distractions like working for a living or playing golf, trees are filtering toxins out of rainwater, providing habitat and breeding grounds for wildlife, cooling the atmosphere, and generally making the world a better place to live. Indeed, it is because of trees that our world is livable at all.
Best-selling author Peter Wohlleben in his landmark book, “The Hidden Life of Trees,” noted that trees create rain. If we were to cut down all the trees in North American, rain would only fall in the 50 kilometres closest to oceans and large lakes, where open water helps to create clouds. The rest of our continent would be a desert, just as the Sahara in north Africa is a desert now. About 10,000 years ago, the same Sahara had trees, grasslands and rivers supported by rain. Recent studies have pointed to humans using the area to graze their flocks — overgrazing, as it turns out. And, well, here we are.
Planting a tree any time is a good idea, but planting a tree now is the best idea of all. The same can be said for planting flowering shrubs and perennials for which the same principles apply.
Which is why it is also a good time of year to dig up and divide perennials. Any perennial with a fleshy or fibrous root system that holds together when you dig it up is good to split and transplant now. Peonies are a good example — divide them with a sharp knife or spade and either move the root clumps around your yard or give them away. Be sure to plant peonies with the top of their roots no more than 10 centimetres deep in their new soil and if the soil is heavy and clay-based plant them only four or five cm deep.
Fall is a good time to also dig up and transplant young shrubs, trees and evergreens. Note that the more fibrous the root system — that is, the denser and hairier the root structure — the more it lends itself to being moved around in your garden. A shrub like burning bush or an evergreen like boxwood can be a decade old and still transplant well.
But a root of heavy wood, like that of walnut or chestnut, will not transplant well at any time. Birch and oak trees buck the fall-planting trend, and are best to dig and replant in spring. We have not figured out why this is so, experience just tells us that it is.