Rootstocks for apple trees

Most apple trees are produced by grafting the required variety (the "scion") on to a rootstock. The main reason for doing this is because the the natural vigour (from low to high) of the rootstock helps to control the size of the mature apple tree. However rootstocks also confer other advantages and disadvantages.

The following table lists apple rootstocks in approximate ascending order of vigour with an indication of the size of the mature apple tree.

Very Small (Very-dwarf)	Small (Dwarf)	Medium (Semi-dwarf)	Large (Semi-vigorous)	Very Large (Vigorous)
P22 M27 G65	G11 M9 G16 Bud. 9 Mark	M26 G935 G202 G30 MM102 Interstems M7 M116	MM106	MM111 Bud. 118 M25
6ft / 2m	8ft / 2.5m	10ft / 3m	14ft / 4m	18ft / 5m

The table should not be taken too literally. Whilst the rootstock is important, the mature height of an apple tree is also affected by numerous other factors. Furthermore, although we have created discrete size bands for convenience, in practice the performance of different rootstocks overlaps considerably.

P22(Very small)

Used commercially on a small scale, produces an extremely compact tree, the same size or smaller than M27, and with better cold-hardiness.

Mature height:	1.5m - 2m
Age starts fruiting:	2 years
Spacing:	1.2m apart
Staking:	Permanent stake required
Good features:	Good cold-hardiness Some resistance to phytophora (crown / collar rot)
Problems:	Susceptible to fireblight Susceptible to woolly aphid Some resistance to mildew
Suitable forms:	Small centre leader, Pyramid, Step-over, Patio-container tree
Requirements:	Regular irrigation and feeding required Ground around the tree should be kept weed-free (e.g. mulched).

M27(Very small)

An excellent rootstock for the enthusiast who wants to plant a lot of apple varieties in a small space - performs very well provided attention is paid to soil and watering.

Mature height:	1.5m - 2m
Age starts fruiting:	2 years
Spacing:	1.2m apart, e.g. 5 trees in 7m
Staking:	Permanent stake required
Good features:	Resistant to collar-rot
Problems:	Fruit size can be small - counter by thinning Very susceptible to fireblight Susceptible to mildew Not cold-hardy for northern North American conditions
Suitable forms:	Small centre leader, Pyramids, Step-overs, Patio-container tree
Requirements:	Regular irrigation and feeding required Ground around the tree should be kept weed-free (e.g. mulched).

G65(Very small)

Developed specifically for North American conditions, with good resistance to fireblight and collar-rot. G65 is derived from the M27 rootstock crossed with a Beauty crab apple, and produces a tree the same size or marginally larger than M27.

If allowed to grow as a regular tree, G65 becomes a small shrub-like ornamental crab apple, with pink/white flowers and red fruits.

Mature height:	1.5m - 2m
Age starts fruiting:	2 years
Spacing:	1.2m apart, e.g. 5 trees in 7m
Staking:	Permanent stake required
Good features:	Some resistance to collar-rot Resistant to fireblight Cold-hardy
Problems:	Not resistant to woolly aphid
Suitable forms:	Small centre leader, Pyramids, Step-overs, Patio-container tree
Requirements:	Regular irrigation and feeding required Ground around the tree should be kept weed-free (e.g. mulched).

Bud.9(Small)

An excellent alternative to M9, with very similar characteristics, perhaps marginally less vigorous. Can 'runt out' and stop growing in some situations, but unsurpassed for winter hardiness in this class.

Mature height:	1.8m - 2.5m
Age starts fruiting:	2-3 years
Spacing:	2.5m between trees
Staking:	Permanent stake required
Good features:	Reasonable fireblight resistance (much better than M9) Resists collar-rot The most cold-hardy M9-class rootstock
Problems:	Sandy soils Susceptible to mildew Slightly susceptible to wooly aphid
Suitable forms:	Small centre leader / Spindlebush, Small bush tree, Oblique cordon
Requirements:	Watering and feeding required Ground around the tree should be kept weed-free (e.g. mulched). Always make sure the tree achieves its full size before allowing it to crop

M9(Small)

M9 was the first standardized rootstock available on a large scale, released by East Malling Research Station in the 1920s, with a lineage going back to the 'Paradise' rootstocks used for many centuries in Europe.

M9 is probably the most widely-planted of all rootstocks, and the mainstay of commercial apple production. There are a very large number of clones of M9, with varying qualities and vigours. Its only real disadvantage is that it is very susceptible to fireblight, which is endemic to some parts of North America.

Apple trees on M9 are very productive and come into bearing within 2-3 years of planting, the tree reaches full size after about 5 years.

M9 is also an excellent choice for the smaller garden or community orchard.

Mature height:	1.8m - 2.5m
Age starts fruiting:	2 years
Spacing:	2.5m between trees
Staking:	Permanent stake required
Good features:	Encourages large fruit size Resists phytophora (collar-rot and crown-rot) - M9 is by far the most resistant of the Malling and Malling-Merton series rootstocks Tolerates heavy / wet soils
Problems:	Susceptible to mildew Slightly susceptible to woolly aphid Very susceptible to fireblight Not cold-hardy for northern North American conditions Can induce brittleness in the scion, so avoid over-cropping at tips of branches.
Suitable forms:	Small centre leader / Spindlebush, Small bush tree, Oblique cordon
Requirements:	Watering and feeding required Ground around the tree should be kept weed-free (e.g. mulched).

G11(Small)

Developed as an improved semi-dwarf M26, but turned out to be a true dwarfing rootstock in the M9 class. Good fireblight resistance (like all Geneva-series rootstocks). Increasingly used in US commercial orchards for very high-density (2ft - 3ft) plantings, and generally easier to work with than Bud 9. unless winter hardiness is the outright requirement.

Mature height:	1.8m - 2.5m
Age starts fruiting:	3-4 years
Spacing:	1m or less between trees
Staking:	Permanent stake required
Good features:	Resistant to fireblight Resistant to crown and root rot Encourages large fruit size
Problems:	Susceptible to replant disease
Suitable forms:	Small centre leader / Spindlebush, Small bush tree
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

G16(Small)

Another good alternative to M9, developed specifically to be resistant to fireblight, which is endemic in parts of North America. G16 is probably the most fireblight-resistant of all the G-series rootstocks. Grows quite rapidly at first but growth is checked once cropping starts. Produces a tree which is similar to or slightly larger than M9.

Unusually for a tree in this size class, G16 has very good anchorage and may not need a permanent support - although probably best to err on the side of caution.

Mature height:	1.8m - 2.5m
Age starts fruiting:	2-3 years
Spacing:	2.5m between trees
Staking:	Permanent stake recommended
Good features:	Very resistant to fireblight Good resistance to collar rot Good cold hardiness, but not as cold-hardy as most other G-series rootstocks A good choice for the home orchardist looking for a small tree
Problems:	Some susceptibility to replant disease Susceptible to woolly aphid Can induce brittleness in the scion, so avoid over-cropping at tips of branches.
Suitable forms:	Small centre leader / Spindlebush, Small bush tree, Oblique cordon
Requirements:	Watering and feeding required. Ground around the tree should be kept weed-free (e.g. mulched). Unusually for a dwarfing rootstock, does not always need a permanent stake

G41(Small)

A new M9-class rootstock derived from M27 and released in 2005. Appears to have all the desirable qualities of M9 but with far better fireblight resistance.

Mature height:	1.8m - 2.5m
Age starts fruiting:	2 years
Spacing:	1m or less between trees
Staking:	Permanent stake required
Good features:	Very good resistance to fireblight (similar to G16) Resistant to crown rot (phytophthora) One of the most tolerant to re-plant disease
Problems:	Some susceptibility to woolly aphid
Suitable forms:	Small centre leader / Spindlebush, Small bush tree
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

Mark(Small)

A specialized and slightly more vigorous alternative to M9 (to which it is closely related) noted for being highly productive. Also known as MAC9. A key point with Mark is that the tree stops growing once fruiting starts, therefore it is important to prevent fruiting until the tree reaches the desired size.

Mature height:	1.8m - 2.5m
Age starts fruiting:	2 years
Spacing:	2.5m between trees
Staking:	Temporary stake required
Problems:	Very susceptible to fireblight Requires specialist management and irrigation to get the best out of this rootstock, not likely to be useful for the home orchardist.
Suitable forms:	Small centre leader / Spindlebush, Small bush tree, Oblique cordon
Requirements:	Very carefully controlled watering and feeding are vital with this rootstock Ground around the tree should be kept weed-free (e.g. mulched).

M26(Medium)

A popular rootstock suitable for most temperate garden conditions, producing a reasonable sized tree. Developed in the UK where it is regarded as being between M9 and MM106 in vigour, elsewhere its vigour can be quite variable, sometimes being little different to M9.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Temporary stake for first 4-5 years, or use a permanent stake in lighter soils
Good features:	Reasonably cold-hardy (unlike other Malling-series rootstocks) and fairly tolerant of difficult conditions.
Problems:	Very susceptible to fireblight Susceptible to collar rot Susceptible (possibly very susceptible) to woolly aphid Soils with poor drainage (which facilitate collar rot)
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

G935(Medium)

Released in 1998 as a semi-dwarf alternative to M26. Produces a tree slightly larger than M26, but significantly more productive. Trees on G935 require permanent support.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Permanent stake always required
Good features:	Reasonably cold-hardy. Resistant to fireblight. Resistant to collar rot.
Problems:	Susceptible to woolly aphid.
Suitable forms:	Central leader tree, Small fan or espalier
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

G202(Medium)

Derived from M27, and similar or slightly larger in size to M26. Can be less productive than G11 or M26 in the USA, but better resistance to woolly apple aphid. In other climates it has been slightly more productive than M26.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Temporary stake for first 4-5 years, or use a permanent stake in lighter soils
Good features:	Good resistance to woolly aphid Resistance to fireblight Resistance to collar rot
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

G30(Medium)

G30 has proven to be an excellent semi-vigourous rootstock, adaptable to most North American conditions and more productive than other rootstocks in its class. Its only disadvantage is that it always requires permanent support.

Size tends to be larger than M26 but smaller than M7. It has much better fireblight resistance and tolerance of wet conditions than M26. Tends to grow vigorously in the first 3-4 years but growth then tails off as fruiting begins.

G30 is by some margin the best (or indeed only) rootstock that will tolerate soils which are subject to flooding.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Permanent stake or other support (wood is brittle)
Good features:	Resistant to fireblight Very tolerant of 'wet feet' - probably the best rootstock to use if your ground is subject to flooding Very productive in a wide range of soil conditions Induces larger fruit size
Problems:	Susceptible to woolly aphid Requires a permanent support in all situations - this is unusual for a rootstock of this vigour category, but is a result of its unusually good cropping potential
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

MM102(Medium)

A rootstock from the Malling-Merton series, derived from the Northern Spy apple variety and resistant to woolly aphid. Remains popular in Australia and New Zealand but little-used elsewhere. Producing a tree similar in size to M26.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Temporary stake for first 4-5 years
Good features:	Resistant to woolly aphid
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

M7(Medium)

One of the most popular apple of the original Malling-series rootstock in North America because it has good fireblight resistance. Can be treated as a small MM106 in most respects.

Mature height:	2.2m - 3m
Age starts fruiting:	3-4 years
Spacing:	3m or more between trees
Staking:	Temporary stake for first 4-5 years, may require permanent stake in lighter soils
Good features:	Resistant to fireblight Resistant to mildew
Problems:	Susceptible to woolly aphid Not especially cold-hardy
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree should be kept weed-free (e.g. mulched).

Interstems(Medium)

Interstems consist of TWO rootstocks, one grafted on top of the other. The scion variety is then grafted on top of the second rootstock. Any combination is possible, but in practice most interstems consist of the MM111 or Bud. 118 rootstocks on the bottom, with a piece of M9 or G11 or Bud. 9 grafted on top (the interstem). This produces a free-standing apple tree which will grow in almost any soil conditions (thanks to the vigorous MM111 or Bud. 118 rootstock), yet is fairly precocious and not too large for the backyard gardener (thanks to the dwarfing interstem).

The mature size is greatly affected by the length of the interstem (the longer the interstem the smaller the tree) so can be quite variable. Usually the intention is to produce a tree comparable to or a bit smaller than MM106.

Mature height:	2.5m - 3m / 10ft - 12ft
Age starts fruiting:	3-4 years
Spacing:	3m / 10ft or more between trees
Staking:	Not required
Good features:	The interstem keeps the overall size down to a manageable height and ensures fruiting early in the life of the tree. The vigorous MM111 or Bud.118 rootstock means the tree can be grown in most soils and probably won't require irrigation, and no staking is required.
Suitable forms:	Bush tree, Small fan or espalier, Large cordon
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed-free until then.

M116(Medium)

M116 is a new rootstock, released in 2002, which can be used as an alternative to MM106. It produces a tree which is about 10% smaller than MM106, but capable of producing the same quantity of apples - making it an excellent choice for small orchards and gardens. It is derived from a cross between the MM106 rootstock pollinated by the M27 rootstock.

Mature height:	2.5m - 3.5m
Age starts fruiting:	3-4 years
Spacing:	3.5m between trees
Staking:	Temporary stake for first few years
Good features:	Resistance to collar rot / phytophora (unlike MM106) Some resistance to woolly aphid (like MM106) Some resistance to mildew Some resistance to re-plant disease
Suitable forms:	Medium/Large bush tree, Medium/Large central leader tree, Large fan or espalier
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed free until then.

MM106(Large)

One of the most popular apple rootstocks, developed in collaboration by the East Malling and Merton research stations in the early 20th century, and derived from the Northern Spy apple variety (which is resistant to woolly aphid) crossed with the Malling 1 rootstock.

Produces a good sized apple tree for the garden or orchard, which can still be mostly worked from the ground or low platforms. If soil conditions are good it does not require much looking after and tolerates low vegetation around it once established.

Mature height:	2.5m - 4.5m
Age starts fruiting:	3-4 years
Spacing:	3.5m - 4m between trees
Staking:	Not essential when planting 1-year trees, otherwise use temporary stake for first few years
Good features:	Resistant to woolly aphid (this was one of the goals of its development) An excellent rootstock for the backyard gardener, provided the soil conditions are good
Problems:	Some susceptibility to fireblight Very susceptible to collar rot / phytophora - best avoided on wet or poorly drained ground Not cold-hardy
Suitable forms:	Large bush tree, Large central leader tree, Large fan or espalier, Half-standard tree
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed free until then.

MM111(Very large)

MM111 is an interesting rootstock, little used in the UK where it was developed, because in the relatively benign UK climate its strengths are not an advantage over other alternatives. However elsewhere in the world MM111 is greatly valued for its ability to grow in poor soils. Its only weakness is that it can take many years for the scion variety to come into bearing. MM111 is frequently used as the basis for interstem trees (see above), a role for which it is perfectly suited.

Mature height:	4m - 5m
Age starts fruiting:	4-5 years
Spacing:	4m - 5m between trees
Staking:	Not required
Good features:	Resistant to woolly aphid (this was one of the goals of its development) Good general disease resistance Some resistance or tolerance of fireblight Resistant to phytophora collar rot (prevalent in wet conditions) Tolerates dry soils, and poor irrigation, and poor quality soils Fairly cold-hardy (compared with the other Malling and Malling-Merton series rootstocks)
Problems:	Can take more than 5 years to come into bearing Some susceptibility to mildew
Suitable forms:	Large bush tree, Large standard tree
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed free until then. Widely used in conjunction with M9 or equivalent interstems, which complement it perfectly.

Bud 118(Very large)

Similar or slightly larger than MM111, but much better cold-hardiness. For most of North America this is the best rootstock for growers wanting a large traditional apple tree.

Mature height:	4m - 5m
Age starts fruiting:	4-5 years
Spacing:	4m - 5m between trees
Staking:	Not required
Good features:	Very cold-hardy Fairly resistant to fireblight
Problems:	Somewhat susceptible to fireblight
Suitable forms:	Large bush tree, Large standard tree
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed free until then.

M25(Very large)

The usual choice for producing a large traditional apple tree in the UK (mainly because it is far more precocious, and slightly larger, than MM111), but little used elsewhere.

Mature height:	5m
Age starts fruiting:	5 years
Spacing:	6m - 7m between trees
Staking:	Not required
Good features:	Relatively precocious - unusual for such a vigorous rootstock Tolerates a wide range of soils, and poor irrigation Although not particularly disease resistant or resistant to phytophora (collar and crown rot) M25 is so vigorous that it can often outgrow these problems
Problems:	Not cold-hardy M25 has a reputation for poor anchorage (i.e. it can be blown over) if planted as a 2 or 3 year-old tree and then allowed to crop quickly. For this reason it is far better to plant 1 year-old M25 trees and delay full cropping until year 5. If faced with planting a 2 or 3-year M25 tree, use a large tree stake to fix the roots immobile and leave it for several years until the tree is properly established.
Suitable forms:	Large bush tree, Large standard tree
Requirements:	Ground around the tree can be grassed after 4-5 years, keep weed free until then.

Whilst the rootstock is perhaps the most important factor in determining the size of an apple tree, there are many other factors which influence it. Our Fruit Tree Height calculator gives more precise information on heights of individual fruit tree varieties.

Rootstock research stations

The above list is not comprehensive, but covers most of the rootstocks likely to be available to apple enthusiasts in Europe, North America, and Australasia. The rootstock names give a clue to their origins:

M-series. The first research into size-controlling apple rootstocks was carried out in the UK by East Malling research station in the early 20th century. The famous M9 rootstock was one of the first released by this programme, and remains the most widely-planted rootstock in commercial orchards. It is a standardised form of one of the French "Paradise" rootstocks, known as Jaune de Metz. (When young, these rootstocks have a yellow sheen to the bark).

MM-series. These stemmed from a colaboration between East Malling Research Station and the John Innes Institute at Merton - hence "Malling-Merton". The main focus of this programme was resistance to woolly aphid. The MM106 rootstock is the most widely-planted rootstock of this series.

G-series.The Geneva series of rootstocks are developed at Cornell University's agricultural experiment station based at Geneva, New York state, beginning in the 1970s, specifically to provide better rootstocks for North American conditions. Resistance to fireblight, tolerance of phytophthora (which causes crown and collar rot in wet conditions) and winter hardiness were the main objectives. All the G-series rootstocks exhibit these qualities to a greater or lesser extent.

Bud-series (Budagovsky). These rootstocks are developed at the Michurin Institute near Moscow, Russia. Exceptional cold-hardiness is one of the aims of this programme. The Bud.9 rootstock is the most succesful of this series and is widely planted in high-density orchards in North America, as an alternative to M9.

P-series. This series of rootstocks has been developed in Poland (the Polish word for rootstock is podkladki, hence "P" series).

Rootstocks and disease resistance

The first scientific research into rootstocks at East Malling focussed primarily on the control of tree height. However researchers soon realised that rootstocks could play an important role in conferring disease resistance as well. The main diseases of apple trees which rootstocks can influence are:

Crown / Collar Rot. A disease caused by the fungus Phytophthora, which attacks the tree and affects either the crown of the tree or the area near the rootstock union - in either case the results are fatal. It is associated with heavy / poorly-drained soils and is prevalent in the eastern United States. Of the early English rootstocks, M9 and M27 proved resistant but MM106 is very susceptible. More info.

Fire blight. A bacterial disease - affected areas of the tree appear blackened as if by fire, and eventually die. The infection generally starts in the blossom and travels down the tree to the rootstock, killing the tree. The disease is prevalent in the north-east of North America. The English M9 rootstock is very susceptible to fire blight. A resistant rootstock allows the grower to cut out the infected parts of the tree, which should then re-grow.

Woolly aphid. A type of insect that sucks the sap from fruit trees, and exudes a white cotton-like residue. Whilst not fatal to the tree, they severely weaken it, reduce crops, and expose the tree to other diseases. Woolly aphid is prevalent in Europe and North America (more so in the southern US states) and is a serious problem for commercial growers in these areas. MM106 was one of the first rootstocks which conferred resistance to woolly aphid, whereas M9 and M27 are quite susceptible and M26 is very susceptible.