The spring season is officially in full swing as we conclude the final week of March. Although the equinox was weeks ago, hints of the winter season continue to rear its frigid head with cool temperatures. The battle between winter and spring season on the day-by-day basis can have many grabbing from both sides of their closets. For the agriculture community, planting too early before the last 32-degree night can have severe consequences. Luckily, the United States Department of Agriculture (USDA) has developed a map to suggest for planters the start of the growing season. It is called the Plant Hardiness Zone Map. Do you know your zone to start planting?
The hardiness map defines 13 zones by annual extreme minimum temperature. The higher-numbered zones are the warmer conditions and lower-numbered zones containing the cooler temperatures annually. For example, the Florida Keys are located in zone 11b compared to Minneapolis, MN being in 4a. The first map for planters was issued in 1927 followed by multiple revisions. The latest update was done in 1990 that introduced 5-degree distinctions dividing each zone into new "a" and "b" subdivisions.
By no means is the map a forecast. Plant hardiness is the ability of a plant to survive adverse growing climates such as drought, flooding, heat and cold. In the Tri State, especially in the spring season, we can experience giant temperature swings. One day it will be in the 70s followed by days in the 30s and 40s. Dynamic shifts such as those could hinder a plant's growth and possibly kill its roots .
Most of the Tri State is located in the hardiness zone of 6b. Our annual minimum temperature ranges between 0 - -5. On a yearly average, the final frost happens between the days of April 9th-17th. The planting/growing season in the Tri State begins the third week of April. Happy planting this growing season!