The plains all the way to Mexico has had an early blast of winter. And since I’ve been thinking it was time to try a long chill cycle in the greenhouse I jumped at the chance. I’ll be running 30s at night and as cool as possible by day until mid February. Days usually end up no warmer than low 60s, mostly 50s, but some like today 40s. That will add up to 1500-1800 Utah hrs. But it’s not really the total chill I’m after but rather a longer dormancy that I think will help the difficult trees like sweet cherries and high chill apricots. Pluots and nectarine/peach can get by fine with less. Past chill cycles have been 45-90 days. This will be the first at 120 days.
That will still leave an 8 month growing season with 7 months of ~90F days.
The first 24 hrs of chilling is off to a fabulous start. The high in the greenhouse has been 45 and low 40F. That’s ideal chilling temperature. Outdoors it’s been heavy low clouds with drizzle and temps in the 30s. Very unusual weather. This won’t last long. But my system of chilling even in sunny warm weather, 60-70F highs, has proven to average ~16 Utah hrs of chilling per day.
It’s just another model for calculating chill hrs. I think it’s a good model for medium to high chill areas and fruits. It gives max chilling to temperatures in the 37 to 48F range. None below freezing and negative hrs above 60F.
