When and How to Fertilise Lemon Trees in Australia

Regular feeding is the key to healthy lemon trees with lush green leaves and heavy crops of fruit. In Australia, where climates range from subtropical to temperate, the timing and method of fertilising make all the difference. Knowing when and how to apply the right nutrients prevents yellow leaves, boosts flowering, and maximises fruiting capacity.

Lemon trees are heavy feeders. Unlike hardier fruit trees, they need consistent nutrition throughout the year to replenish energy after harvests and fuel their next cycle of growth. A well-timed fertiliser schedule ensures balanced foliage, strong root systems, and reliable fruit set. Neglecting feeding leads to nutrient deficiencies, poor flowering, and reduced fruit quality.

The most important feeding times are early spring, mid-summer, and mid-autumn. In northern Australia, an additional late-winter feed may also be beneficial. Avoid heavy fertilising in winter, as cooler temperatures slow tree activity and excess nutrients can leach away unused.

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Best Fertiliser Practices for Lemon Trees

Spring Feeding (September–October): Kickstarts new leafy growth and supports flowering. Apply a balanced fertiliser with nitrogen, phosphorus, potassium, and trace elements.
Summer Feeding (January–February): Sustains fruit development during the hottest months. Consistent water and nutrition at this stage prevent small or dry lemons.
Autumn Feeding (April): Replenishes nutrients after the main harvest, preparing the tree for the next cycle and strengthening its root reserves.
Young Trees: Fertilise lightly but frequently to encourage steady root and canopy growth. Avoid strong doses that can burn delicate roots.
Mature Trees: Apply fertiliser evenly around the dripline of the canopy. Water in well to carry nutrients into the root zone.

The best results come from a complete fertiliser tailored to citrus needs. Complete Grow NPK 20-20-20 provides nitrogen for lush leaves, phosphorus for strong roots, and potassium for heavy fruiting. Magnesium and trace elements help prevent common problems like yellowing leaves. Use liquid fertiliser every 4–6 weeks during active growth, or powdered forms for slower release.

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FAQs About Fertilising Lemon Trees in Australia

When is the best time to fertilise lemon trees?
In spring, summer, and autumn. Avoid heavy feeding in winter when growth slows down.

How often should I fertilise lemon trees?
Every 4–6 weeks during the growing season. Frequent light feeds are better than a single heavy application.

What happens if I don’t fertilise regularly?
Leaves may turn yellow, flowering may reduce, and fruit size and flavour will suffer.

What is the best fertiliser for lemon trees in pots?
A balanced feed such as Complete Grow NPK 20-20-20 Liquid is ideal for container citrus, as nutrients leach from potting soil more quickly.

Can I over-fertilise lemon trees?
Yes. Overfeeding, especially with too much nitrogen, leads to excessive leafy growth at the expense of flowers and fruit. Stick to recommended rates.