I had a call from a customer this week wondering why the apple trees that he purchased five years ago hadn’t blossomed yet. I told him that apples typically take 2 to 6 years to begin bearing so it wasn’t unheard of that they hadn’t blossomed yet, but if he was running out of patience he could try the following.
With a sharp knife cut all the way through the bark to the wood. Don’t remove any bark, just score it all the way through the bark half way around the tree. Then repeat the process an inch above the first mark, but scoring the other half of the trunk. This will almost sever the “lifeline” of the tree, shutting off the downward flow of carbohydrates, so they accumulate in branches and twigs. This will shock the tree into self preservation mode. I have recommended this to customers in the past and 9 times out of 10 the tree will blossom the next year. Because the wound is clean and very small it heals very quickly with no permanent harm to the tree. Scoring is best done in the late spring right after the tree fails to bloom.