Repotting guide

When & how to repot Rough-Shelled Macadamia (Macadamia tetraphylla)

Also called rough-shelled macadamia, Queensland bush nut.

More about rough-shelled macadamia

About Rough-Shelled Macadamia

Macadamia tetraphylla · also called rough-shelled macadamia, Queensland bush nut · edible

The rough-shelled macadamia is the hardier, more cold-tolerant cousin of M. integrifolia, distinguished by four-leaf whorls, prickly juvenile foliage, pink-tinged flowers, and rough, sometimes sweeter nuts. This subtropical evergreen wants frost-protection, deep acidic well-drained soil, and steady moisture, and is widely used as a parent in commercial hybrids for its vigour and flavour.

Mature size: 8-18 m tall and 6-10 m wide in the ground; pruned and grafted trees are kept considerably smaller in cultivation.

Watch for — Phosphorus toxicity: High-phosphorus fertilisers scorch and yellow the leaves by damaging proteoid roots. Always feed with low-P, Proteaceae-suitable products.

How to tell rough-shelled macadamia needs repotting

Repotting on a calendar is less reliable than reading the plant. For rough-shelled macadamia, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot rough-shelled macadamia on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot rough-shelled macadamia

Pot on seedlings as they grow; not a perennial repot. Rough-Shelled Macadamiais grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Vigorous evergreen tree with whorls of (usually) four leaves, prickly when juvenile, and pink-flushed flower racemes. Somewhat more upright and cold-hardy than the smooth-shelled species, with rough-textured shells..

What size pot to step rough-shelled macadamia up to

Pot rough-shelled macadamia on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot rough-shelled macadamia

Pot rough-shelled macadamia on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting rough-shelled macadamia

Pot on before it is root-bound. Check rough-shelled macadamia regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh deep, fertile, free-draining acidic loam with high organic matter at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water rough-shelled macadamia in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for rough-shelled macadamia

Rough-Shelled Macadamia wants deep, fertile, free-draining acidic loam with high organic matter. Prefers pH 5.0-6.5. The proteoid root mat needs friable, well-aerated soil; it dislikes heavy clay, alkalinity, and salt. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting rough-shelled macadamia — frequently asked questions

How often should you repot rough-shelled macadamia?

Pot on seedlings as they grow; not a perennial repot for rough-shelled macadamia. Rough-Shelled Macadamia is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into deep, fertile, free-draining acidic loam with high organic matter so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does rough-shelled macadamia need?

When is the best time of year to repot rough-shelled macadamia?

Can you put rough-shelled macadamia straight into a much bigger pot?

No. Even a fast-growing rough-shelled macadamia should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise rough-shelled macadamia after repotting?

Not immediately. Wait about 1 week after repotting rough-shelled macadamia. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.