I am particularly interested in quantifying the impact of spring frost on growth of spruce trees. To do so, I cut hundreds of trees sampled from two plantations established in two contrasting environments and I analyzed how these trees responded to the mean annual temperature and spring frost frequencies. I performed a stem analysis which consists in sampling tree discs along its stem to accurately measure annual height growth and to identify each frost rings. After dating ~ 50 000 tree rings, I analyzed the relations between the presence of a frost ring and the annual height growth and I further compared to capacity of the mean annual air temperature to predict the annual height growth compared to using past frost frequency and intensity. I found that extreme climate events like spring frosts can predict the annual height growth with greater accuracy! This finding is important because models of tree growth only consider aggregated temperature metrics like the mean annual temperature or growing degree-days to forecast future growth trajectories of temperature and boreal tree species whereas nnual height growth should be predicted by extreme climate events.