Safe Temperatures for Winter Pruning

This is our Royal Red Honeycrisp block. Originally these trees were Red Delicious. We grafted them to RR Honeycrisp in 2016.

Mild Winter Until This Week

Our crew of pruners has been busy pruning our acres of Honeycrisp trees for the past couple of months. The winter pruning temperatures so far have been fairly mild, allowing few interruptions for adverse weather.

According to WSU AgWeatherNet (AWN), from January 1 – February 8, the average minimum temperature here at the 2,000′ elevation in Chelan Washington is 27.9°, and the average maximum temperature is 37.3°F. The general thinking is that if the pruners can stand the cold, so can the trees.

Head For the Heated Shop

We farmers always have our eyes on the weather. A significant drop in temperature in the long-range forecast makes us take heed! We start texting each other and checking different weather apps. If the consensus is that the cold is imminent, then we’ll immediately have the crew take a break from pruning. Pruning causes reduced cold hardiness in fruit trees; the best practice is to stop at least 5 days before the expected cold weather. According to Lynn Long, Extension Horticulturalist at OSU, a pruning cut invigorates the tissue around the cut, making the branch less cold-hardy than a non-pruned limb.

Happy Pruners and Happy Trees

Why are winter pruning temperatures relevant now? Because over the weekend, the forecast prediction for this week showed lows around 3°F with a maximum of around 17°F. So beginning today, the crew moved inside the heated shop to build sprinklers for our new irrigation system and wait for warmer weather before pruning again.