The Spring Snow crab apple has a very dense, upright, oval crown. It has showy white, abundant blossoms without producing the fruit. It has a very good resistance to cedar apple rust and mildew, which makes it an excellent choice. It requires full sun and is tolerant to a wide range of soil conditions. The mature height of the tree can be 20 to 25 feet and the width can grow to 15 to 20 feet.
Do you plan on having a double row of the trees or just one row? If you are looking for it to become a screen in a couple of years, I would plant them 12 feet apart, staggering the trees of the second row in between. If you plan on a single row of trees, you may want to plant them closer for quicker screening.
One fact to remember is that this crab apple tree is susceptible to fire blight, a bacterial infection, so if you do any pruning on these trees, the pruning should be done in late winter. If pruned during the growing season, there is the threat of fire blight infecting the wounds. Check this site for more information on fire blight:
http://www.extension.umn.edu/yardandgarden/ygbriefs/p223fireblight.html
