Gadenin日本語Get the appWhere the crop actually comes from
Macadamia flowers hang in long trailing racemes that emerge from wood produced during the previous growing season, mostly on the older, shaded interior of the branch rather than the leafy tip. That single fact governs every pruning decision you make.
Shear the outside of the tree the way you would a hedge and you remove precisely the wood that was about to flower, which is why a tidied-up macadamia so often produces almost nothing the following year. The tree does not need thinning for light in the way an apple does, because it fruits happily in its own shade.
So the working rule for an established tree is: cut for structure, safety and access, and nothing else. A mature macadamia that is well shaped may need no more than a few cuts a year.
The training years: build one strong leader
The first three or four years are when pruning earns its keep. The aim is a single central trunk with well-spaced branches leaving it at wide angles, because narrow forks in brittle macadamia wood split out under a crop or in a gale, usually taking half the tree with them.
- Pick the leader and stick with it Choose the strongest, straightest vertical shoot and remove any rival growing up alongside it. Trees left with two competing leaders eventually split down the middle at the fork.
- Remove tight forks early Any branch leaving the trunk at less than about 45 degrees is a future breakage. Cut it out while it is still thinner than a pencil and the wound closes in one season.
- Space the main branches Keep branches that are eight to twelve inches (20 to 30 cm) apart vertically and spiralling around the trunk. Take out whorls where three or four branches all leave from the same point.
- Take the lowest branches off gradually Lift the skirt to about two feet (60 cm) over two or three seasons, one or two branches a year. Removing them all at once checks the tree badly.
- Stop training once the frame is set By the fourth or fifth year the structure is decided. From then on, switch to light maintenance cuts and let the tree carry its own wood.
Prune young trees after the main growth flush, when the new wood has hardened. Cutting into soft, actively extending growth invites dieback at the wound.
When to cut, and how much
The safe window on a bearing tree is straight after harvest, once the last nuts are off the ground and before the tree starts pushing the growth that will carry next year's flowers. Cutting later removes flowering wood; cutting in cold weather leaves an open wound at the worst time of year.
Keep the total to well under a fifth of the canopy in any one year on a bearing tree. Macadamias respond to hard cutting with a mass of vertical watershoots that carry no crop and shade out the wood that would have.
| Timing | Do this | Avoid |
|---|---|---|
| Immediately after harvest | Structural cuts, skirting, dead wood | Nothing; this is the main window |
| Start of the growth flush | Rub out unwanted shoots by hand | Saw cuts into hardened wood |
| Flowering and nut fill | Only broken or diseased limbs | Any shaping; you are cutting off the crop |
| Cold season | Nothing | All pruning; wounds close slowly and frost follows the cut |
The skirt, and why ground harvest depends on it
Because macadamia nuts drop to the ground when they are ready, the ground under the tree is your harvest floor. Branches that sweep down and rest on the soil make the nuts impossible to find, hold damp against the trunk and give rats a covered run into the canopy.
Keep the lowest branches at least two feet (60 cm) clear of the ground on a garden tree, and cut back anything that flops onto the soil under the weight of a crop. Make the cut back to a side branch that grows upward or outward, not to a stub.
Cuts to make, cuts to leave alone
Always take out dead wood, crossing branches that rub, anything broken in a storm, and the vertical watershoots that spring up along the top of horizontal limbs. Always cut back to a branch or to the collar, never leaving a stub, and never paint the wound with sealant.
Leave alone the short, twiggy, apparently unproductive growth on the shaded inside of the branches. It looks like clutter and it is where a large part of your crop is formed. Leave alone, too, any large limb you are tempted to remove to reduce height: dropping a mature macadamia's height by a third is a two- or three-year project, taken a little at a time, not a single afternoon's work.
Never top a macadamia by cutting the leader flat across. The tree answers with a dense brush of weak upright shoots at the cut, and the resulting structure is both unproductive and dangerous in wind.
Keep a note of what you cut
Record the date of every pruning session and roughly which parts of the tree you worked on. Because the effect on the crop shows up a full year later, a dated note is the only way to learn whether last season's cuts helped or cost you nuts.
It is worth sketching the tree once and marking the main limbs. When a branch has to come off for safety, you can then see at a glance what the tree will look like without it.