If you are considering growing your own apples, there are several factors to consider beforehand. While apples will grow pretty much anywhere as long as there is a period where the temperature drops below 45o F so that they have a dormant season, apples can be very prone to pests if they are not given ideal conditions. This is one reason cultivars are so much more popular than antique apples. But with careful selection and some diligent care, apples can be grown as low or no-spray crops.
All trees now sold commercially are grafts. The top portion is the variety you have chosen. This is called the "scion". It is the part that bears the fruit and requires your attention as a grower. The scion is grafted onto the "rootstock" of an apple tree that has desirable characteristics such as rot resistance or dwarf height. Rootstocks are generally designated by the letter "M" followed by some numbers. For instance M.9 will produce a strongly dwarfed tree of about 8 - 10 feet, but is susceptible to fire blight. M.26 will grow a little taller, 11 - 14 feet, but should be more resistant to fire blight. Rootstocks are crucial to the health of the tree, but have no affect on the fruit.
Another major consideration with apple growing is pollination. Few apple varieties are self-pollinating. Some are even sterile. In general, all apple varieties should be considered self incompatible and at least two varieties should be grown. Additionally, you'll need to make sure those varieties are in bloom at the same time. Your nursery should be able to help you find two varieties that are compatible and no, you can't use two trees of the same variety. If space is a consideration, you might want to consider a tree with grafts of more than one variety on that single tree. If you already have a crab apple tree nearby, that could serve as a pollinator providing it too blooms at the same time as your apple variety.
Apples aren't that particular about soil conditions except that they don't like wet feet. Give them adequate nutrition, full sun and protect them from animal damage, especially in the winter, and you are on your way. Check out one of these excellent articles online, for more details on growing your own apple trees: Penn State's College of Agricultural Sciences. "Small-Scale
