Air layering

A cutting has to survive on what's stored inside it. An air layer never has to: you wound a branch, wrap the wound in damp moss, and the branch grows roots into the moss while the tree keeps feeding it. When the roots are ready you cut below them, and you have a tree that was never, at any point, a stick in a cup. On figs, which root eagerly, the success rate is close to total.

When

While the tree is in active growth — late spring through midsummer, when it's warm and the sap is moving. A layer started in June is usually ready by August. Don't start one in autumn; the roots won't form before the tree shuts down.

The eight steps

1. 1

   Choose the branch

   Healthy, pencil-to-thumb thick, this year's or last year's wood. Pick a spot 30–60 cm (1–2 ft) back from the tip, on a straight section with no side branches for a hand's width.

2. 2

   Girdle it

   Make two cuts around the branch about 2–3 cm (an inch) apart, join them with a lengthwise cut, and peel off the ring of bark. Then scrape the slippery green layer underneath — the cambium — off the exposed wood. If you leave it, the bark just heals over and nothing happens.

3. 3

   Hormone, if you like

   Dust or paint rooting hormone on the top edge of the wound. Optional on figs. Cheap insurance.

4. 4

   Wrap in moss

   Soak sphagnum moss, squeeze it until it stops dripping, and pack a fist-sized ball of it around the wound. Damp, not wet. Same rule as cuttings.

5. 5

   Seal in plastic

   Wrap the moss in cling film or a square cut from a plastic bag, and tie or tape both ends tightly to the branch. No moisture in, no moisture out.

6. 6

   Cover with foil

   Wrap the whole thing in aluminium foil. It keeps light off the forming roots, keeps the sun from cooking them, and — genuinely — stops birds pecking at the shiny plastic.

7. 7

   4–8 weeks

   Wait, then peek

   Lift the foil after a month. You're looking for white roots pressed against the plastic. If there are only a few, wrap it back up and give it two more weeks. You want the moss ball full.

8. 8

   Cut, pot, shade

   Cut the branch just below the root ball. Remove the plastic, leave the moss, and pot it in a container of potting mix. Trim a third of the leaves so the new roots aren't asked to support a whole canopy, and keep it in the shade and humid for two or three weeks before treating it like a tree.