Interstem Grafting of Apples: small trees, big roots

In which I use the tricky manipulation of grafting 3 different apple varieties together to create trees that are small yet drought resistant

UPDATE: to see my new video series on interstem grafting, click here!

Inter-stem trees sprouting on in the nursery row.  Note two bandages on each tree.

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A long time ago fruit tree grafters selected certain rootstocks that would create smaller trees for small gardens and special purposes like espalier training.  Dwarfing rootstocks are naturally small varieties of trees that confer their diminutive size to the fruit varieties grafted onto them.  Early grafters had to make due with a limited selection of these dwarfing stocks, but these days there are ever smaller and more improved dwarfing rootstocks selected for size, rooting characteristics, disease resistance and ability to confer early fruiting to the variety grafted to them.  Some of these modern stocks make trees of only a few feet in height.  Last year I picked apples in a 30 year old orchard that had been grafted onto the dwarfing rootstock Malling 7.  The trees were only about 7 to 8 feet tall making picking and maintenance very easy.  These trees were also heavily loaded with fruit.  One drawback to using dwarfing rootstocks is that they tend to be shorter lived than normal sized fruit trees.  I’m planting trees for posterity and not just for myself, so I usually gravitate toward larger and healthier stocks.  After observing these ease of handling with these small trees and noting that they seemed to be doing well after 30 years I figured maybe there was a place for some dwarfed apples here.

Dwarfed trees may tend to be shorter lived, but they bear at a younger age and can give higher yields per acre when planted at closer spacings.  That’s a nice advantage.  I decided to put in a group of dwarfed trees grafted to varieties suitable for hard cider making.  First I looked for a good dwarfing stock in the 9 to 12 foot high range and decided on the newer Geneva 30 rootstock.  Alas, everyone seemed to be out of it because it was late in the season.  Then I got onto the idea of using an inter-stem.

In inter-stem grafting (also known as double working and interstock) a normal sized vigorous rootstock is used for the roots of the plant, a second variety of dwarfing rootstock is grafted on top of that, and the fruit variety to be grown out is grafted on top of the dwarfing inter-stem.  The result of this strategic placement of genetic materials is a fruit tree of the variety you want, dwarfed by an inter-stem but with a full sized root system to feed it.