Can I plant figs in an unheated greenhouse in Zone 6?
Answer: The biggest variable in whether this endeavor will be successful is the duration of cold. For example, three fig growers in northwest Arkansas have had the same experience the last three years. They all achieved whole-plant survival and fruit in years 2012 and 2013, despite temperatures that once dipped down to -18 degrees F in 2012. However, it was -18 degrees F for only 12 to 24 hours, and that very cold temperature was preceded and followed by more temperate temperatures. However, this past winter, which dipped to zero only a couple of times, all of the three growers’ figs were killed to the ground, including the cold-hardy Celeste, Brown Turkey, and Hardy Chicago cultivars (they’re now re-sprouting from the roots). This is because temperatures stayed below freezing for a week or two several times.The good news for you is that you do have a structure that should buffer the rate of temperature change and protect from desiccating wind. My best advice is to stick to the cultivars with the reputation for cold hardiness and be ready to supply supplemental heat from some source if it’s going to get below 10 degrees F for extended periods. You might also consider some sort of framework that would allow you to drape tarps or blankets over the trees and provide some heat lamps or some other relatively safe source of heat for those coldest nights. It shouldn’t take much to heat such a setup within the already wind-protected greenhouse. In fact, you’ll need to be careful that temperatures inside such a structure don’t get warm enough to predispose the tree to worse cold damage. You might also consider walling off some section of the greenhouse that you can dependably heat during the coldest periods?just enough to keep it above freezing, perhaps.I wish I had better advice or word of some new miracle cultivar or invention that would make it easier, but at least I doubt that a fig in a greenhouse like you describe would ever freeze below ground?you should always at least get a breba crop. For more information on fig resistance to cold, visit www.planetfig.com/articles/fareng2589.html.