Cherry trees present a particular challenge because when grown on their own roots they are potentially the largest of all fruit trees, certainly much larger than wild apple trees. Until the 1970s there was not much that gardeners or commercial growers could do when growing cherries but accept that the trees would be large, would take up a lot of space, and most of the cherries would be so high up that the birds would get there first. Fortunately recent research programmes have resulted in new rootstocks that produce smaller more manageable trees - useful for commercial growers and ideal for gardeners.
Gisela 5 (G5)
Introduced in the 1990s, Gisela 5 has quickly established itself as the rootstock of choice for gardeners who want a cherry tree with manageable proportions. It produces a tree about 3m / 10ft tall after 5 years or so - roughly equivalent to the apple M26 rootstock, and about 50% the size of a "standard" cherry on seedling rootstock.
Cherry trees on Gisela 5 cannot support themselves so you will need a 2m permanent stake or other means of support. Training against a wall or trellis works well with Gisela 5 (and also means you can more easily cover the tree in early summer to keep the birds away). It is important to provide good growing conditions, including regular feeding and watering, and to keep the area around the tree free from competing weeds or grass. However these are minor inconveniences compared to the attraction of being able to pick your own fresh cherries, and if you can provide the necessary growing conditions then cherry trees on Gisela 5 are reliable croppers.
Commercial orchards on Gisela 5 are typically laid out with 2m between trees in the row, and 4m between rows.
Gisela 5 was developed as a cross between two species of ornamental cherry, Prunus cerasus (the sour cherry) and Prunus canascens.
This is a new semi-dwarf rootstock, producing a cherry tree very similar in size to the Gisela 5 rootstock. The main advantage for UK growers is that both the yield and fruit size are slightly improved over Gisela 5. This rootstock is also more tolerant of drought and the higher summer temperatures found in southern Europe, and has some resistance to replant syndrome.
Krymsk 6 was developed from Prunus cerasus (the sour cherry). It is a semi-dwarf rootstock, suitable for both hot and cold climates.
This sister rootstock of Weigi 2 is also in the semi-dwarf class, but it is about 10% more vigorous than Gisela 5 (and Weigi 2). This makes it a better choice for poor soils, or less vigorous varieties. In other respects it is similar to Weigi 2, with better productivity and larger fruit size than Gisela 5, better drought tolerance, and better able to cope with high summer temperatures.
Gisela 6 (G6)
Gisela 6 produces a slightly larger tree than Gisela 5, roughly equivalent to the apple MM106 rootstock. The main advantage over Gisela 5 is that it is much less fussy about soil conditions, and in most situations it is free-standing and does not need support.
Whilst Gisela 5 is becoming the most popular rootstock for cherry orchards in northern Europe and the north-east USA, in the hotter summers of the Pacific North West growing region of the USA, Gisela 6 is preferred.
Like Gisela 5, Gisela 6 is also developed from Prunus cerasus (the sour cherry) and Prunus canascens.
This rootstock is widely used in commercial cherry orchards in the Pacific North West of the USA. It is a semi-vigorous rootstock, roughly similar or slighly more vigorous than Gisela 6. It is not as precocious or productive as the Gisela rootstocks, but fruit quality is good and it is arguably easier to manage the trees.
Although developed specifically for cold-hardiness, this rootstock also performs well in hot climates and heavy soils. No support is necessary.
Unlike many other modern cherry rootstocks it is not developed from Prunus cerasus.
This is the best rootstock for growing cherry trees in large gardens and community orchards. It produces a tree with a height of 3.5m - 5m, and tolerates poorer soils than Gisela 5 and needs less looking after. It's also useful for large cherry fans. Colt is roughly comparable to the apple MM111 rootstock.
This is a traditional cherry rootstock and produces a very large standard cherry tree, with a mature height of 6m. It is perfect for traditional orchards, although it is quite slow-growing and the large trees might be difficult to harvest from - unless your objective is feeding the local birds.