Forecasted temperatures give a green light for planting
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Many locations in Michigan saw multiple freeze and frost events, but forecasted milder low temperatures will allow gardeners to plant tender plants. Locations that have not passed their frost-free dates should keep an eye on the low temperatures.
Figure 1. The growing degree days (GDD) base 50 degrees Fahrenheit as of May 16, 2021 (left) versus the average GDD since 1981.
Spring came early to much of Michigan. As of April 1, 2021, the growing degree days (GDD) accumulation was 14 days ahead in majority of the state of Michigan. GDD is a temperature-derived index that is calculated based on the amount of heat accumulated above a base threshold temperature such as 50 degrees Fahrenheit and is strongly related to the rate of plant growth and development. The heat map of Michigan represents GDD between 0 and 338 GDD (Figure 1). The warmer the color, the more heat has accumulated in the area.