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.
M9 stock is used around the world to produce apples that can be picked by hand.
M27 also produces a very dwarf tree which can be used as a freestanding tree in small gardens or in a pot. We have a very productive m27 in our garden.
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 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. Trees reach around 10 feet. 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.