Question
we have a flowering crabapple tree that was given to us by a neighbor about 6 years ago. it's about 7-8 feet tall now and has never flowered. we've been told by a few people that if it was a "volunteer" tree, it will never bloom. Is this true? We have regular apple trees close that have produced for the last 2 seasons. We live in northern Minnesota and the trees are planted in soil that has been amended (from heavy clay) and there is full sun. It's a pretty tree and I hate to see it go, but.....

Answer
That should not be the case for crabapple. Age and size are more important. Also the type of soil and the need to fertilize the the will play a part.  Proper fertilization should be done annually to encourage blooming and increased healthy growth. When choosing a fertilizer for your flowering trees you can use either a liquid or powdered form; they provide equal benefits to the trees.

Apply fertilizer in the fall or early spring. Choose a fertilizer that is a bloom booster for your flowering trees, to increase the bloom production in the spring. This type of fertilizer is a 5-30-5 blend, which is a compound blend of 5 percent nitrogen, 30 percent phosphorous and 5 percent potassium.

Spread the fertilizer at the base of the flowering tree. The amount of fertilizer depends on the age and size of the tree. I would use the above fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. Make sure you do not use a lawn type fertilizer that contains a herbicide--these are the Weed and Feed type. The herbicide will kill the tree. Apply the fertilizer just before a rain event and you will not need to water. IF you have not done so mulch around the tree with not more than 3 inches deep of organic mulch not piled up on the trunk. This will help hold moisture around the roots.