Growing Degree Days for Ontario Permaculture Sites

Due to the geographic distances between regions in Ontario, there is a massive variation in the potential thermal energy that a permaculture site has at it’s disposal. This thermal energy is measured by a metric called Growing Degree Days.

Growing Degree Days (GDD)

GDD are a measure of heat accumulation used by horticulturistsgardeners, and farmers to predict plant and animal development rates such as the date that a flower will bloom, an insect will emerge from dormancy, or a crop will reach maturity.

Looking below, you can see that Leamington has 2574 GDD and Thunderbay has 1377 GDD. A permaculture site in Leamington, Ontario has almost twice the available GDD as one in Thunderbay,

Based on the the GDD, a Food Forest in Northern Ontario, might want to consider the following:

  • Keeping a very open tree canopy in order to maximize light hitting the ground and use as much of the heat potential of the sun as possible.
  • Maximize under-story shrubs to take advantage of their longer growing seasons and hardiness (currents, gooseberries, apples, hazelnuts, mulberries, raspberries, blackberries, haskap, and more).
  • Use of mix of coniferous and deciduous trees. Especially consider the use of mixed-species hedgerows to create suntraps around and throughout the food forest.
  • Aspect of the land. For instance, a site with terrain such that the it is on the north-side of a slope will receive even less sunlight then the theoretical maximum available for that site.
  • Consider the use of ponds to increase the thermal energy available for plants in their vicinity, and therefore creating a beneficial micro-climate.
  • Good inspiration and important alternative approaches can be found in the Madawaska Forest Garden by Steven Elliot Martyn. Mr. Martyn made clearings in the dense forest using for reference the Mayan Milpa system, citing as inspiration the idea that in both the tropics and central-northern Ontario, the forests hold most of their resources in the trees and plants as opposed to the soil (which is often thin. The result of the milpa system was a patchwork forest, that had both mature groves of fruit and nuts trees, but also open fields densely filled with corn. Below is a photo I took in Southern Belize, on the sites of an ancient Mayan city, depicting a corn field amidst the forests engulfing the long forgotten city.

What do you think? Any other ideas?

Leave a Reply

Your email address will not be published. Required fields are marked *