A variety of rootstocks are available for grafting onto them any variety of apple you want. These rootstocks produce trees that are as short as 5 to 6 feet (1.5 m to 2 m) called dwarfs, or full size "standard" trees as high as 30 feet (9 m) and others that are somewhere between. A new type of apple tree called "columnar" or "colonnade" adds a new dimension to apple tree structures. These broomstick type of trees, which are characteristic of specific varieties of apples, lend themselves exceptionally well to high density orchards and container planting.

Some varieties of apples such as Wealthy, New Brunswick, Lady, Idared, Macoun and Paulared are naturally smaller trees, so when grafted onto dwarfing rootstock they will be even more dwarf than other varieties on that same rootstock. For this reason the dwarfing properties of rootstocks are given in percentages of standard tree height rather than a dwarfing height.

Dwarfing rootstocks don't always have strong and hardy root systems and so another method has been developed. A dwarfing rootstock piece is grafted onto a hardy root such as Antonovka and then an apple cultivar such as Wealthy is grafted onto the top. The dwarfing piece which is located between the rootstock bottom and the cultivar top is referred to as an interstem.

Grafting tender apple varieties on cold hardy rootstocks such as Bud 491 or Bud 490 may make it possible to grow them in a hardiness zone which is colder than what they are rated. Bud 490 rootstocks produce very hardy and healthy trees in the orchards in the author's region. They are more resistant to disease than Bud 491 but are much larger trees.

Generally the more vigorous a rootstock is, the less efficient it is in producing apples, however for the Kitchen Orchard efficiency is not a prime concern. In the Maritime Provinces, Beautiful Arcade seedlings, or Beautiful Arcade seedlings with Ottawa 3 interstem, have proven to be very cold hardy and reasonably productive. Evidence of this cold hardiness can be seen in this picture taken following the severely cold winter of 1992. One nursery in New Brunswick, Corn Hill Nursery, has been propagating both BAs and O3 rootstocks for over 10 years with proven success. The Federal Research Station in Fredericton experimented with rootstock combinations in the early 1990's which showed favourable results (including high yields) using P16 as an interstem on BA seedlings and O3 on M111 rootstocks.

Cold hardiness of trees is not always a factor of the tree and roots simply withstanding prolonged cold temperatures. M7 rootstock will suffer severe damage after 24 hours at -8 to -10°C ground temperatures (no snow cover), while many other rootstocks will tolerate -14°C. Few, however, will survive colder ground temperatures. Another factor affecting cold hardiness is the tree's ability to harden off before severe cold weather arrives. Some types of rootstocks can impart early hardening off to the tree, while others can delay it. Too much growth in a tree can also prevent proper hardening off and some rootstocks can cause a tree to be too vigorous and "leafy."

Below are listed a few of the many rootstock varieties in use today. Many more are under development.

Malling Series:

The Malling (M or EM) series was developed from Quince bush roots at the East Malling Research Station in England, 1912-1917.

 Rootstock  Size  Characteristics
 Malling I (M1)  60% No support needed. More productive than M2. Subject to crown rot.
 Malling II (M2)  65% No support needed. Not hardy. Tends to lean.
 Malling III (M3)  65% Roots sucker. Best used as an interstem. About as hardy as Alnarp 2.
 Malling IV (M4)  50% Roots form on one side. Staking needed for support. Doesn't like wet soils. Not hardy.
 Malling V (M5)  75% Needs support. Very productive.
 Malling VII (M7)  50-65% Developed from a series of French rootstocks, "Doucin Reinette," known as the Doucin group, dating back to 1688. It is known to contain a latent virus. Introduced by East Malling Research Station in 1974. Support M7 while young. Tends to sucker unless budded 16 inches high and planted deep. EMLA 7 shows less suckering than M.7. Spreading roots which penetrate deeply. Resists collar rot and fire blight except when in poorly drained soils. Susceptible to woolly apple aphid. Doesn't like heavy clay soil. Sensitive to wet ground. EMLA 7 is hardier than M26 and M9 but M7 is less hardy (suffering considerable damage at -8  to -10 °C). M7 suffered serious winter kill in New Brunswick in 1992. M7 is not precocious (early bearing), taking up to 5 years or more to fruit. Hardens off early in season. Will bear fruit for 25-30 years. Not compatible with Winesap.
 Malling VIII (M8)  30% Smaller than M9 but roots are not as brittle. Nevertheless support is needed. Use as an interstem. About as hardy as Alnarp 2.
 Malling IX (M9)  20-40% Selected from a number of "Juane de Metz" rootstocks that date back to Medieval France and the "Paradise Tree" of ancient Persia. Most popular rootstock in Europe. Small root system. Must be staked throughout life. Not hardy. Brittle wood and roots. The thick bark tends to be less cold hardy than the thin bark of M7 which hardens off sooner. The rootstock overgrows the scion making a lump on the main leader. More tolerant to wet and more resistant to collar rot than M26. Trees on M9 have a higher calcium and magnesium content than those on M7. Very susceptible to fire blight and wooly apple aphid. Particularly attractive to mice. Precocious (3 years). The most common clone of M9 in North America is NAKBT 337. Other clones from largest to smallest include Pajam 2, RN29, Pajam 1, EMLA, NAKBT 337, Fleuren 56.
 Malling XI (M11)   Similar to M16 in hardiness. Less hardy than Antonovka, Hibernal, and Robusta #5.
 Malling XII (M12)  100 - 105 % Good anchorage. Normal otherwise.
 Malling XIII (M13)  100% Shallow spreading root system. Grows well where a hardpan soil prevents deep root penetration or where high water tables prevail for certain periods.
 Malling XVI (M16)  100% Good anchorage. Matures late. Normal otherwise.
 Malling XXVI (M26)  45-55% Originally M3436, a cross between M16 (Metziner Ideal) and M9. Suffered serious winter injury in N.B. in 1992. Also very susceptible to fire blight and woolly apple aphid. Brittle roots. Rootstock overgrows the scion making a lump on the main leader which reduces the supply of nutrients to the tree. Roots grow on one side causing it to lean so it may need staking, especially in windy areas. Keep graft union close to ground. It doesn't tolerate wet conditions but it resists collar rot. Very susceptible to fire blight. Late to harden off. Precocious (2-3 years). Fruit tend to be lower in calcium than on other rootstocks.
 Malling XXVII (M27)  15-20% Strictly a patio container plant. Not more than 6 feet tall. Highly barked, corky, brittle root system. Require staking. Requires excellent, well drained soil conditions. Susceptible to fire blight. Use only with vigorous scions or the tree may "runt out."

Merton Malling Series (MM)

Developed jointly by the East Malling Research Station and the John Innes Horticultural Institute at Merton in the 1920's as a cross between Malling and Northern Spy. All are wooly apple aphid resistant but not immune. They carry the Pl1 and Pl2 genes for powdery mildew resistance. All have the same hardiness. The numbered series runs from 101 to 115.

 MM104  50% A cross between M2 and N. Spy. Well anchored with spreading roots which penetrate deeply, but dies in poorly drained soils. Does not stand drought well either.
 MM106  65-75% A cross between M1 and N. Spy. Well anchored, non suckering, productive. Subject to collar rot and fire blight. Avoid poorly drained soils. Bears fruit in 3-4 years. Very productive, yields better than M7. Not cold hardy in the colder area of the Maritimes. Hardens off later than M7 and M111. Delicious should not be propagated on this rootstock due to the development of apple union necrosis disorder.
 MM109  70% Roots grow on one side. Discontinued due to bad tree leaning tendency. Poor anchorage.
 MM111  75-85% A cross between Merton 793 and N. Spy. A general purpose, upright tree for all varieties. Not precocious, fruiting after 6 to 7 years. Good anchorage. Drought tolerant, that is, it is efficient at extracting water from the soil. Does not tolerate wet soils - developing crown and root rot. Some resistance to fire blight. Prone to suckering. Cold hardy (early to defoliate and harden off).

EMLA series (the "clean" series)

This series is the same as the Malling (M or EM) and Merton Malling (MM) series but it lacks the latent virus present in the Mallings. However, the trees may vary from the "dirty" MM series in certain characteristics. For example the "dirty" M9 is the most dwarfing of the M9 series. The "clean" M.9EMLA is the most vigorous of the M.9 selections and M.9NAKB337 (a virus-free selection from Holland) is the most dwarfing of the "clean" M.9's but as dwarfing as the virus-infected M9.

Some Other Rootstocks

 Robusta #5  80-100% Canadian. Baccatta X Prunifolia. Similar to Alnarp 2. Winter hardy. Good anchorage. Tends to be thorny and difficult to bud graft. Should be budded up to 2 ft high because of its trunk hardiness. Moderate resistance to fire blight. One positive attribute for this rootstock is that it appears to be immune to wooly apple aphid (See the Geneva Series below). Although it was bred to be hardy, it comes out of dormancy early and so is subject to mid-winter thaw/freeze cycles (this rootstock was nearly eliminated in N.B. in the 1982 freeze). Short lived, about 10 years.
 Alnarp 2  65-75% From Sweden. Same size as M111. No more hardiness than the M or MM series but with better, well anchored roots. Good for windy areas. Has a good form. Very vigorous. Susceptible to Mg deficiency and to fire blight and canker.
 Ottawa 3  30-40% Some warmer climates report only 50 - 55% dwarfing. Developed at Ottawa, Canada. A cross between M9 and Robin Crab. Very hardy. Has been tested in the Canadian prairies since the 1960's and was officially recommended as a rootstock for the prairies in 1997 by Rick Sawatski, fruit breeder at the University of Saskatchewan. Does best in well drained soils. Requires staking if used by itself. Dislikes being moved, once planted. Best results are with young rootstocks. O3 survived the harsh winter of 1992 in New Brunswick which killed many of the Mallings. Resistant to virus. Very susceptible to fire blight and to wooly apple aphids. Resistant to crown and root rot. It may promote anthracnose canker with some cultivars such as McIntosh, Empire and Paulared. Fruits growing on Ottawa 3 may be smaller than on other dwarfs and yields may be less in maritime climates where there are lower heat units. Used as an interstem on Beautiful Arcade very successfully. A newer strain, Ottawa 103, is more productive and precocious.
 Beautiful Arcade seedlings
(BAs or BA)
 65-80% Beautiful Arcade is a Russian dessert apple brought to Canada in 1885 and tested and released by the Ottawa Experimental Station as a very hardy variety. Seedlings of BA are very uniform, and easy to grow. In the Maritimes Ottawa 3 is often used as an interstem on this rootstock giving a very hardy combination. BAs rootstocks tend to produce suckers especially if O3 is used on them. Not precocious or productive unless used with O3 interstems.
 Mark (Mac 9)  35-45% Developed at Michigan State University from an open pollinated M9. Doesn't mind wet, heavy, soil, actually prefers it. Can survive -20°F without snow cover. Not as hardy as M26. Precocious (1-2 years). Very susceptible to fire blight. It may also cause some cultivars to be susceptible to anthracnose canker. Use only with vigorous scions or the tree may "runt out." Late note: No longer available because the burrknots it develops strangle the tree after several years.
Budagovski series 20%-70%

This series was developed at the College of Horticulture in Michurinsk, Siberia by Soviet rootstock breeder, Dr. Budagovski, who died in 1975. Very cold hardy. Hardier than O3 and recovers well from winter root damage. It works well as an interstem on BAs which produces a 40% tree.

Bud 9 is a M8 X Red Standard cross. Produces sturdy trees between M9 and M26 in size (25-30% standard size). Very resistant to collar rot. Moderately resistant to powdery mildew and apple scab. Very susceptible to fire blight and wooly apple aphid. Rooting ability similar to M7. Hardy, recommended as an interstem in colder areas. Doesn't like wet soils. Efficient.

Bud 490 is a Bud 9 X Bud 13-14 cross. Produces trees 65-70% standard. Well anchored. Comparable to MM106. Does not sucker. May develop burrknots. Medium resistance to collar rot. Susceptible to wooly apple aphid. Induces early, heavy bearing. Very winter hardy. Grafts heal strong.

Bud 491 is a very hardy, super dwarf producing 20% standard trees. Precocious and heavy producer. A well anchored rootstock but requires crop support. Susceptible to collar rot and fire blight. Can be used as an interstem. Efficient. Use only with vigorous scions or the tree may "runt out."

 Antonovka  90% A Russian dessert and cooking variety. Very hardy. In use for over 500 years. Tolerant to clay soils. Hardy to Zone 3.
 Borowinka  100% Duchess Apple. Most compatible and vigorous of cold hardy rootstocks. Does better than Antonovka in wet soil conditions. Hardy to Zone 3.
 Baccata Crab  80-90% A wild Siberan crabapple. Extremely hardy, Zone 2 or colder. May be incompatible with some cultivars. Fragrant, white to deep pink flowers. Great for using as a shelter belt from cold winds. In prairie conditions it is a smaller, semi- dwarf rootstock and can be planted closer together than normally recommended.
 Polish series  6% -40%

The Polish series (P1, P2, P16, P22, etc.) was developed by Dr. S. W. Zagaja at Skierniewice, Poland.

P2. A cross between M9 and Antonovka, Resists collar rot, canker, silver leaf and crown gall. Very susceptible to fire blight. Produces 35% to 40% standard size trees. Non suckering. About as hardy as Antonovka but not as hardy as Budagoviski.

P22. A cross between Antonovka X M9. Not as hardy as Budagoviski. Well anchored. A rapid grower. May show some incompatibility to some varieties. Use only with vigorous scions or the tree may "runt out." Resistant to crown gall, collar rot, canker, scab and powdery mildew. Very susceptible to fire blight. A very efficient rootstock. About 25% to 30% standard size and about 16% of the crop of standard trees. A good rootstock for container planting.

 Columbia Crab  100% Vigorous. Very compatible with most cultivars. Somewhat susceptible to crown rot. Hardy to Zone 3.
 Prunifolia  100% Hardier than Antonovka but not as hardy as Baccata. Extensive fibrous root. Zone 3.
 Ranetka Crab  100% Hardier than Antonovka but not as hardy as Baccata. More vigorous than Baccata and less problems with compatibility with some cultivars. Chosen by Sprout Farms in Bon Accord, Alberta as being the best overall rootstock for the prairies when hardiness, drought tolerance, compatibility, and tree growth and vigour ar all combined. Purple, oblong fruit if let grow. Available only from Lawyers Nursery at time of this publication. Hardy to Zone 2.
 Selkirk Crab  80% From Manitoba, Canada. A very hardy rootstock. If allowed to grow it produces a broad based tree with attractive, deep pink flowers and beautiful bright red, cherry sized fruit. Hardy to Zone 2.
 Geneva Series (CG)  

A very new rootstock series from Geneva, N.Y. bred for disease and pest resistance. For example CG.65, the first to be released, is well anchored, precocious, very productive, resistant to powdery mildew, crown rot and highly resistant to fire blight.  Some suckering; nearly no burrknots.  CG.11 is similar to M26 but it is very resistant to fire blight, collar rot and woolly aphids. It also has far fewer burr knots. CG.30 has been trialled in Nova Scotia since 1992. It is about 25% as dwarfing as M7 and it is moderately resistant to fire blight. Prone to suckering. Another series which includes CG.179, CG.202 and CG.210 contain good resistance to wooly apple aphids received from Robusta 5.

See Internet reference below for up to date information on Geneva rootstocks.

 Vineland Series (V)  20%-50% A relatively new rootstock series developed by Dr. John Cline, Simcoe, Ontario, Canada ( See web links #8 & #9 below. A cross of Kerr x M9 and very hardy, precocious, and fireblight resistant, ideal for the cold prairies. V1 and V2 are freestanding and of M26 or slightly larger size. V3 needs to be staked and is M9 sized. Productivity is very comparable to M9 and better than M26.

1. Dwarfing Rootstocks (Minnesota Extension Service)
2. Disease Resistant Rootstocks; Novole, G.65, G.16, G.11, G.30 etc. (Cornell University)
3. Sources of Geneva series rootstocks
4. Use of dwarf apple rootstocks in high density planting systems (Department of Horticultural Sciences, New York State Agricultural Experiment Station, Cornell University, Geneva, New York)
5. East Malling Research Station, England
6. East Malling Research Station, History
7. East Malling research work and publications
8. International Dwarf Fruit Tree Association
9. The Horticultural research Institute of Ontario, Simcoe Research Station
10. Dr. John Cline's research work at Simcoe, Ontario