2012 Annual Report for FNE11-727
Raising fig trees in high tunnels in the Northeast
Summary
Coming through the winter of 2011-2012, there was concern that the project would not be able to show that the high tunnel could protect figs in cold winters since we had one of the mildest winters in recent times. All the figs that were alive, in the fall of 2011, were also alive in the spring of 2012. That held true for all three plots including the unprotected plot.
The protected plot was uncovered on March 5, 2012. Bud swelling was noticed at that time. This put the protected plot well ahead of the high tunnel and the unprotected plot since no bud swell was noticed at that time in either of those plots. The next three weeks however showed a marked difference in the high tunnel plot. The unprotected plot showed no difference from March 5, 2012. The protected plot showed growth stopping during that time. The high tunnel however, had made very good growth and had leafed out during that three week interval.
This can be attributed to the warmer temperatures in the mostly closed high tunnel. The high tunnel was only ventilated during very warm days. The final report data will show harvesting began three weeks earlier in the high tunnel than the other two plots. It will also show higher yields in the high tunnel since there was a longer frost free season for the figs to ripen. There were many trees in both the protected and unprotected that had on average about 15 unripened fruits and as many as 75 when frost hit. The high tunnel had almost no unripened fruit since all the fruit produced that year had been previously harvested.
During the summer of 2012, we had a Derecho, a rare straight line storm with very high winds, on July 1. The covering on the high tunnel was lost along with the data monitors, but none of the fig trees were affected in any of the plots. We were able to have the covering replaced within a few weeks, so it had no effect on the figs since it was very warm during that whole period of time.
We have found that six by seven foot spacing is too close together for mature trees. In many of the trees, new growth comes from the bottom foot of the plant and as it seeks sunlight, it grows almost horizontal for a couple of feet before turning upward. This made it very difficult to get between the trees for picking fruit, and may lead to reduced yields. I would recommend a spacing of eight feet by eight feet for all fig tree plantings. Even when the trees grow very large, they can be pruned back to maintain that spacing.
At this point in the research, we can show a definite benefit to using high tunnels for fig production. It extends the season long enough to almost guarantee a good harvest. Not part of the research was two fig trees that were growing in the heated greenhouse. They were only three weeks ahead of the high tunnel unheated trees. It might even be possible to only have to cover the high tunnel during the late winter and spring season with lighter plastic to achieve the same results.