Fertilising guide
How to fertilise Macadamia (Macadamia integrifolia)— schedule & NPK
Also called macadamia, smooth-shelled macadamia, Queensland nut.
More about macadamia
About Macadamia
Macadamia integrifolia · also called macadamia, smooth-shelled macadamia · edible
The smooth-shelled macadamia is a handsome subtropical evergreen yielding the world's richest dessert nut. Native to coastal Queensland rainforest, it wants warm, frost-free conditions, deep fertile acidic soil, and steady moisture. Trees are slow to bear (grafted plants in 4-6 years) but long-lived and productive, with glossy foliage and pendulous sprays of cream flowers.
Growth habit: Dense, rounded evergreen tree with whorled, glossy leaves and long racemes of cream flowers followed by hard-shelled nuts in a green husk. Moderate, somewhat brittle growth that benefits from wind shelter.
Watch for — Phosphorus toxicity: Standard high-P fertilisers damage the proteoid roots, yellowing and scorching leaves. Always use low-phosphorus feeds formulated for Proteaceae or natives.
What fertiliser macadamia actually wants — and why
Macadamia is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for macadamia: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed macadamia, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For macadamia:
Feed little and often with a low-phosphorus fertiliser; Proteaceae are phosphorus-sensitive and high-P feeds cause toxicity. Use balanced, gentle, slow-release products and supplement with potassium during nut fill. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when macadamia is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for macadamia
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for macadamia. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water macadamia first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the macadamia watering schedule.
Signs you are over-feeding macadamia
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for macadamia:
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding macadamia
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full macadamia care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush macadamia with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for macadamia
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising macadamia — frequently asked questions
What fertiliser does macadamia need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Macadamia is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed macadamia?
Feed little and often with a low-phosphorus fertiliser; Proteaceae are phosphorus-sensitive and high-P feeds cause toxicity. Use balanced, gentle, slow-release products and supplement with potassium during nut fill. Feed little and often with a low-phosphorus fertiliser; Proteaceae are phosphorus-sensitive and high-P feeds cause toxicity. Use balanced, gentle, slow-release products and supplement with potassium during nut fill. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for macadamia?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for macadamia. The variable that actually matters is pH, not concentration.
What does over-feeding macadamia look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding macadamia an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of macadamia?
Flush macadamia with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Macadamia care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water macadamia — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise tomato
- How to fertilise pepper
- How to fertilise cucumber
- All 5561 fertilising guides in the Growli library