Why can you not simply grow a beloved old apple variety from seed? Because from the pip something new arises, almost never the mother variety. Anyone who wants to keep a particular variety must propagate it vegetatively, and the classic method for that is grafting.
It sounds like secret knowledge but is a craft you can learn. With a little practice you rescue a nameless farm variety from your grandparents' tree, make an unfruitful tree fruitful with an added pollinator, or raise a family tree with several varieties. This article shows you the two most important techniques.
Two plants become one
In grafting you join two parts: the rootstock, which provides the roots and vigour, and the scion of the desired variety, which supplies leaves and fruit. For them to fuse, the wafer-thin green growth layers under the bark, the cambium, must touch.
Which rootstock you choose sets the tree's later size. That is so fundamental it deserves its own article: Understanding fruit tree rootstocks. Onto the same rootstock you can graft almost any suitable variety.
The two most important methods
Budding and whip grafting
- Budding in late summer
You set a single bud of the scion variety under the rootstock's bark. The window is late summer, weeks 30 to 34, when the bark lifts easily. Sparing with material, high success rate.
- Whip grafting in winter
You join a whole scion to the rootstock through matching slanted cuts. The window is late winter before bud break, weeks 9 to 13.
- Top-working old trees
Onto an existing, healthy tree you can graft a new or second variety. That turns a tree without a pollinator into a bearing one.
- The family tree
Several varieties on one trunk, grafted onto different branches, bring diversity in a small space and solve pollination at the same time. Ideal for small gardens.
How to graft successfully
Cut scions at the right time
For winter grafting, cut the scion in dormancy from healthy, one-year-old shoots and store it cool and moist. For budding, take the bud fresh in late summer.
Cut cleanly and quickly
Use a razor-sharp grafting knife. The cut surfaces must neither dry out nor get dirty. Do not touch them with your fingers.
Cambium to cambium
Line up scion and rootstock so the green layers just under the bark meet, on at least one side. This is where the two grow together.
Bind firmly
Wrap the join snugly with grafting tape so nothing slips and no air reaches the wound. On whole scions, also seal the cut ends with grafting wax.
Wait for the take
If the bud or scion shoots after a few weeks, the graft has taken. Loosen the tape before it constricts, and remove competing shoots from the rootstock.
Cambium to cambium, clean and quick, snugly bound. The rest is practice. Every successful graft preserves a variety that would be lost from seed.
The core rule for grafting
Frequently asked questions
Why can't fruit be grown true from seed?
Because from the pip a new cross arises that almost never resembles the mother variety. To keep a particular variety, you must propagate it vegetatively, classically by grafting onto a rootstock.
What is the difference between budding and whip grafting?
In budding you set a single bud under the bark in late summer. In whip grafting you join a whole scion in late winter through slanted cuts. Both are quite doable in the home garden.
When is the best time to graft?
For budding, late summer, weeks 30 to 34, when the bark lifts easily. For whip grafting, late winter just before bud break, weeks 9 to 13. The scions for it you cut back in deep dormancy.
Can I graft several varieties onto one tree?
Yes, that is the family tree. Onto different branches of one tree you set different varieties. That brings diversity in a small space and solves pollination, because the varieties pollinate each other.
What is the cambium and why does it matter so much?
The thin, green growth layer just under the bark. Only when the cambium of scion and rootstock touches do the two form shared tissue and grow together. If they do not meet, the graft fails.
