This permits spring seeding to start when soil temperatures reach a suitable level and not to wait until the last chance of frost disappears. The crop stage most susceptible to frost damage is flowering. Length of Frost Free Period in Days for Five Alberta Locations. The growing season is the period of time each year during which perennial crops such as pastures and forages can grow. The growing season is longer than the frost free period.
Plant growth begins whenever air and soil temperature are above freezing most of the time.
The start, end and length of the growing season will be different every year. The variability in the average start, end, and length of the growing season will be similar to that illustrated in Tables 1 and 2 for the frost free period. This information can be used to compare the growing season length across the province. As with frost free period and degree-day calculations, the length of growing season does not account for the effect of longer day length in northern Alberta compared to southern Alberta. Small areas of above average conditions will be found around Edmonton and in the vicinity of Taber and Bow Island.