Who Knew? Wednesday – “Zoning” Out

Do you know when it will be safe to put in your garden this spring? 

 You need to know which zone you are in.  The U.S. Department of agriculture divides the country into zones according to the average low winter temperature.  There are thirteen zones including the continental US, Alaska, Hawaii and Puerto Rico with 1 being the coldest and 13 being the warmest.  The zones vary in 10-degree increments.  For example, the average cold winter temperature for zone 1 is 10 degrees colder than the one for zone 2.

2019-04-03 Who Knew Wednesday –USDA map NJ.jpg

 Within each zone is a sub-zone with a 5-degree difference indicated by an “a” or “b” suffix.  For example the average coldest winter temperature in zone 5a will be 5 degrees colder than zone 5b.

 Here in Randolph, NJ we are in zone 6a which has an average minimum winter temperature of -10°F to -5°F

 Now that you know about what zones are, you need to know about Frost Dates within each zone.

 In Zone 6a, the frost dates are:

  • Average Date of Last Frost (spring) is April 15th

  • Average Date of First Frost (fall) is October 15th

 This means that you can start thinking about putting in a garden after Aril 15th and by October 15th you should be thinking about protecting less hardy plants and bringing your potted houseplants indoors.  Remember that these dates are averages.  The actual last frost date in the spring could be 2 weeks or more after April 15th so plan accordingly.  The same goes for fall – the first frost could arrive earlier than expected.

 For an interactive map of all USDA zones, see the USDA website at https://planthardiness.ars.usda.gov/PHZMWeb/

 Plant carefully so you don’t risk your investment.  Happy gardening!