Grafting fruit trees: a beginner's guide

Grafting sounds like something only nurseries do, but it's a skill any home gardener can learn. With a sharp knife, some tape and a bit of practice, you can grow a favourite old apple, add a pollination partner to a lonely pear, or turn one tree into a fruit salad tree.

What grafting is

Grafting joins two plants so they grow as one. There are two parts:

• Rootstock: the lower part, with the roots. It controls things like the size of the tree and how well it copes with soil and disease.
• Scion: the piece of stem you attach on top. It decides what fruit the tree produces.

The key to every graft is the cambium. This is the thin green layer just under the bark, where new cells form. When the cambium of the scion touches the cambium of the rootstock and is held firmly, the two grow together.

Why graft at all

• True-to-type fruit. Most fruit trees don't come true from seed. Plant a pip from a lovely apple and you'll get a different apple, often a poor one. Grafting is how you copy a variety exactly.
• Size control. Dwarfing and semi-dwarfing rootstocks keep trees smaller, which suits backyards.
• Toughness. Some rootstocks handle heavy soil, drought or particular pests and diseases better.
• More than one variety. You can graft several varieties onto one tree, as long as they're compatible. This is handy for pollination and for small spaces.
• Faster fruit. A scion taken from a mature tree usually fruits sooner than a seedling.

Compatibility

Grafts only take between closely related plants. Apples graft onto apples, and pears onto pears or quince. Most stone fruit (peaches, nectarines, plums, apricots and almonds) can be grafted onto each other in many combinations, but not every pairing is reliable. Apples won't take on a plum. If in doubt, stick to the same species.

The main methods

Budding uses a single bud rather than a length of stem. It's thrifty with scion wood and is how many nurseries produce stone fruit trees.

Timing in Adelaide

1. Collect scion wood in winter (June to August) while the tree is dormant. Choose healthy, pencil-thick shoots from last season's growth with plump buds.
2. Store it cool and moist. Wrap the cuttings in a slightly damp paper towel, seal them in a plastic bag, label them and keep them in the fridge, away from fruit. Ripening fruit gives off ethylene, which can spoil the buds.
3. Graft in late winter to early spring, as the sap begins to rise in the rootstock and its buds start to swell. The scion should still be dormant.
4. Bud in summer, when the bark is slipping, meaning it lifts easily away from the wood. Chip budding can also be done into early autumn.

Safety first

Grafting knives are very sharp. Always cut away from your body and keep your other hand behind the blade. Work slowly on a stable surface. A cut-resistant glove on the hand holding the wood is a sensible extra.

Step by step: a cleft graft

A cleft graft is a good first graft for adding a new variety to an existing tree.

1. Choose a branch on the tree about 2.5 to 5 cm thick, with straight, smooth bark.
2. Cut it off square with a pruning saw, leaving a clean, flat top.
3. Split the stub. Place a strong knife or cleft tool across the middle of the cut and tap it down to make a split about 5 cm deep.
4. Prepare the scion. Take a dormant scion with two or three buds. Cut the base into a long wedge about 3 to 4 cm long, with one side slightly thicker than the other.
5. Open the cleft with a screwdriver or wedge.
6. Insert the scion at the edge of the cleft, thicker side outwards, so its cambium lines up with the rootstock's cambium. Because the bark of the stock is thicker than the scion's, the scion will sit slightly inward of the outer bark. Line up the green layers, not the outer surfaces.
7. Put a second scion on the opposite side of the cleft if you like. It doubles your chance of success.
8. Remove the wedge so the stub springs closed and grips the scions tightly.
9. Seal everything. Cover the top of the stub, the split and the cut ends of the scions with grafting tape or grafting sealant so nothing dries out.
10. Label it with the variety and the date.

Aftercare

• Check the graft every week or so. Swelling buds and new leaves on the scion are good signs.
• Rub off shoots that come from the rootstock below the graft, or they'll compete with the scion.
• If both scions in a cleft take, keep the stronger one and cut the other back to a short stub, removing it fully the following year.
• Loosen or remove tape once the union has grown together, usually within a few months, so it doesn't strangle the stem.
• Protect new growth from wind and birds. A stake or a light splint stops young shoots snapping off at the join.
• Water the tree during dry spells, especially in its first summer.

Why grafts fail

• Cambium not lined up. The most common cause. The green layers must touch.
• Drying out. Exposed cut surfaces or poorly sealed grafts dry quickly, especially in wind.
• Wrong timing. Scion wood that has already started to grow, or a rootstock that's still fully dormant, can struggle.
• Movement. If the scion is knocked or wobbles, the new tissue tears.
• Dirty or blunt tools. Ragged cuts don't join well, and dirty blades can bring in disease.
• Incompatible plants. Some combinations never take, however well you graft.

Don't be discouraged by a failed graft. Even experienced grafters lose some. Do several at a time, and you'll learn something from each one.