What is cool season gardening?
There is a whole category of vegetables and edibles happiest in cooler temperatures, including many that can handle a light frost or even dusting of snow! Here in Southern Ontario, that means seeding and planting in August, for harvest beginning September and usually lasting into November. Cold frames, cloches, mulches and row covers with insulating fleece frost blankets can also extend this cool season right up until winter sets in.
Cool season gardening is defined more by temperature than date. In our climate zone, cool season crops grow best when the air temperatures average around 20°C, and soil is 10°C – 20°C in the root zone, 12-15 cm beneath the surface of the soil. Below 10°C, nutrient absorption slows and mycorrhizal fungi are less active. Using a soil probe to monitor the temperature in a few areas of your garden can be beneficial as different pockets of soil will warm and cool at varying rates. Finding a location in your garden that stays fairly consistent can be as important as finding the right soil temperature.