I have been reading a variety of articles and research papers regarding winter fertilizing trees. By winter, Im referring to the range from early to late winter. Most of the articles that I read from scientific literature refer to recent plantings, such as for nurseries or evergreen groves. The results do not appear clear cut. They also do not extrapolate well to a home orchard. In some cases, there was increased growth - height and trunk girth - the next season, or the leaves were greener.
I wonder if anyone fertilizes their fruit trees and plants during the winter? I have not done a controlled experiment. I could see it being helpful. Spring is a busy time, and it’s hard to get everything done. Especially for someone slow, like me, or someone busy. Fertilizing now would be one less thing for later. Some writers think that as long as the ground is not frozen, tree roots take up and store some nutrients, for better growth during the most active early growing season.
Since we use a woodstove, we have a lot of wood ash, rich in calcium (roughly half that of lime) much needed in my acidic, low calcium soil, potassium, and some other minerals. The winter and early Spring rains seem to wash the ashes into the soil. For nitrogen, a urea fertilizer might soak into the soil into the root zone, better during the wet season than later.
On the negative side, nobody wants to pollute the groundwater or waterways with nitrogen and phosphorus fertilizers that wind up leaching without being taken up into tree roots and grasses or other plants. Possibly with fertilizing, would Spring growth be more lush and more susceptible to late frosts?
I was wondering what others think, and especially the voice of experience on growingfruit.org. During most winters, at least my fig trees get a dusting of wood ashes, and I don’t see any harmful after effects. Also around some young shade trees. Most of the rest of the ashes go to kitchen garden beds, especially for tomatoes, greens, and sweetcorn. But I was wondering about fruit trees, brambles, and vines. As for nitrogen, I’ve done that with chestnut trees, bamboo, and cypress, but not most of the fruit trees.