UK’s Center for Crop Diversification has a brand new planting calendar available for high tunnel growers in Kentucky. This calendar is an excellent visual aid to help growers plan their plantings dates. The calendar accounts for Kentucky’s three distinct climate zones, so be sure to click on the picture in which your county is highlighted in blue. Most of eastern Kentucky will be either Region 2 or Region 3.
When you are planning your planting dates, there will be some additional factors that you should consider before going by the exact dates on the calendar. Make sure you pay attention to your actual air temperature and compare it to the air temperature sidebar on UK’s calendar that gives you the acceptable ranges for each crop. As we all know, weather patterns change from year to year affecting temperatures in high tunnels. Another factor affecting air temperature inside a high tunnel would be single vs. double poly layers.
You will also want to pay attention to your soil temperature. Low soil temperatures will affect germination if direct seeding, and can also stunt transplant growth causing them to be less vigorous. I will use tomatoes as an example – minimum soil temperature for tomato transplant survival is around 55° for most varieties. However, at the minimum temperature, they may be very slow to mature and might not be as healthy in the long run. So for tomato transplants, we recommend waiting until the soil is above 60°. Trying to be the first to market with your tomatoes? The ones transplanted in the warmer soil may develop harvestable fruit as fast, or faster, than the ones that were transplanted at the cooler temperature, even if they were planted a little later in the season.
If in doubt, contact your local extension agent, or one of Grow Appalachia’s Small Farm Production Advisors for more information about optimal planting conditions and well adapted varieties for high tunnels.