All of our fruit trees are grafted onto one of a number of rootstocks, some of which have names, many just numbers and letters! So a brief explanation follows…
Apples are grafted onto apple rootstocks primarily to reduce their size.
M27 produces a very dwarf tree which can be used as a freestanding tree in small gardens or in a pot. It produces a very productive little tree. Also suitable for a pot.
M9 rootstock is the choice that all professional growers use to grow their apples on. It produces a tree that is productive and easy to pick.
M26 will produce a tree around 10 feet tall and in my garden with lots of fruit. Good for cordons or small espaliers. Will start to produce quantities of fruit in a couple of years.
M116 will produce trees intermediate between m26 and mm106. Would also make a good espalier or cordon in most gardens.
MM106 is a vigorous tree in Scotland and produces a tree 10 to 15 feet high. Can be used to form a traditional looking orchard. Takes a bit longer to produce the quantities seen on more dwarfing stocks.
M25/ M111 rootstocks produce a very vigorous tree up to 25 feet tall, and will take 5 years or more to start producing fruit.
We have been using Gisela 5 dwarfing stock for our cherries for s number of years now. Trees reach 8 to 12 feet depending on the variety. You may also see Colt, a more vigorous stock.
We use a dwarfing stock for small gardens, Quince A. Sometimes the even smaller Quince C stock. Trees reach around 6 to10 feet with these. For the traditional orchard, we use pear seedling as the stock. These trees will grow 20 feet or more and live to a great age.
There are several stocks for plums.
VVA1 forms a good garden sized tree.
St Julien and Wavit are quite vigorous and will produce a tree about 15 feet tall. Very productive.
Brompton gives a strong tree 20 feet or more in height. For the large garden or orchard.