The USDA Plant Hardiness Map

Zone 1 Below -50F
Sow seed in early spring when soil can be worked

Zone 2 -50F to -40F
Sow seed in early spring when soil can be worked

Zone 3 -40F to -30F
Spring:
April 15 - June 15
Fall: August 15 - October 1
Dormant plant when soil temp. is below 50F.

Zone 4 -30F to -20F
Spring:
April 15 - June 15
Fall: September 1 - October 15
Dormant plant when soil temp. is below 50F.

Zone 5 -20F to -10F
Spring:
April 15 - June 15
Fall: September 1 - October 15
Dormant plant when soil temp. is below 50F.

Zone 6 -10F to 0F
Spring:
March 15 - May 15
Fall: September 15 - November 1
Dormant plant when soil temp. is below 50F.

Zone 7 0F to 10F
A Fall planting
is recommended
Fall:
September 15 - November 15

Zone 8 10F to 20F
A Fall planting
is recommended
Fall:
October 1 - December1

Zone 9 20F to 30F
A Fall planting
is recommended
Fall:
October 1- December 15

Zone 10 30F to 40F
A Fall planting
is recommended
Fall:
October 1 - December 15

Zone 11 Above 40F
A Fall planting
is recommended
Fall:
October 1- December 15

For your convenience, we have reproduced the new USDA Plant Hardiness Map. The hardiness zones are based on the average annual low temperature for each zone. Many factors, such as altitude, snowcover, degree of exposure to wind, proximity to bodies of water, excessive or minimal rainfall, soil types, etc. can create variations within zones. Please understand that these abnormalities can adversely affect your wildflowers. Thus, the spring and fall planting dates should be considered generalizations. The above factors have a dramatic effect on predicting precise sowing dates for each zone.


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