Fertilising guide

How to fertilise Finger Lime (Microcitrus australasica)— schedule & NPK

Also called finger lime, Australian finger lime, citrus caviar.

More about finger lime

About Finger Lime

Microcitrus australasica · also called finger lime, Australian finger lime · edible

The Australian finger lime is a thorny rainforest citrus prized for its caviar-like vesicle pearls that burst with tart juice. Slow-growing and frost-tender, it thrives in a sheltered, sunny spot or a large container moved indoors over winter. Expect fruit from late autumn, with cultivars ranging from green to crimson pulp.

Growth habit: Densely twiggy, thorny evergreen shrub with small leaves and a naturally bushy, somewhat sprawling form; can be trained as a compact standard or hedge.

Watch for — Magnesium/iron chlorosis: Interveinal yellowing on older or new leaves signals nutrient lockout; correct pH and apply chelated micronutrients.

What fertiliser finger lime actually wants — and why

Finger Lime is a hungry evergreen fruiter with specific needs — a dedicated citrus feed, switched between summer and winter formulas, keeps it cropping and green.

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 finger lime: 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 finger lime, 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 finger lime:

The dormant-season rule matters more than the exact interval: skip feeding entirely when finger lime 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 finger lime

Follow the citrus-feed label rate for finger lime and use the correct seasonal formula. The trace-element content matters as much as the NPK — substituting a general feed is the usual cause of yellowing.

Feeding always goes onto already-damp soil, never dry roots — water finger lime first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the finger lime watering schedule.

Signs you are over-feeding finger lime

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for finger lime:

Salt crust on the soil and scorched, browning leaf tips.
Excess soft leafy growth with poor fruit set from too much nitrogen.
Leaf drop shortly after an over-strong feed.

Signs you are under-feeding finger lime

Yellowing leaves — overall pale, or yellow between green veins (magnesium/iron).
Poor flowering and fruit set, small or dropping fruit.
Weak new growth and a generally tired tree.

If the symptoms point at watering, light or roots rather than nutrition, the full finger lime care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Potted finger lime accumulates salts and benefits from a thorough plain-water flush every couple of months until it drains freely, plus an annual repot or top-dressing of fresh citrus compost.

Organic vs synthetic feeds for finger lime

Organic options

Well-rotted manure or compost mulch plus seaweed and an Epsom-salts (magnesium) drench supports finger lime naturally. UK: organic citrus feed or seaweed + Epsom salts; US: Espoma Citrus-tone or Dr. Earth Citrus.

Synthetic / liquid feeds

A proprietary summer and winter citrus feed — UK: Westland or Vitax Citrus (summer/winter); US: Miracle-Gro or Espoma Citrus. Using the right seasonal formula is the key to keeping finger lime green and cropping.

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 finger lime — frequently asked questions

What fertiliser does finger lime need?

A specialist citrus fertiliser, which carries the higher nitrogen plus the magnesium, iron and trace elements citrus need — generic feeds quickly leave it yellow and chlorotic. Many ranges have a summer (higher-N) and a winter (lower-N) formula. Finger Lime is a hungry evergreen fruiter with specific needs — a dedicated citrus feed, switched between summer and winter formulas, keeps it cropping and green.

How often should I feed finger lime?

Feed with a high-nitrogen citrus fertiliser fortnightly from spring through late summer, switching to a winter citrus feed in the cool months. Watch for magnesium and iron deficiency (interveinal yellowing) and correct with chelated micronutrients. Feed with a high-nitrogen citrus fertiliser fortnightly from spring through late summer, switching to a winter citrus feed in the cool months. Watch for magnesium and iron deficiency (interveinal yellowing) and correct with chelated micronutrients. In practice: a summer citrus feed regularly (often roughly fortnightly) from spring to autumn, switching to a winter citrus feed at a reduced rate over the colder months — citrus feed year-round, unlike most container plants.

What strength of feed for finger lime?

What does over-feeding finger lime look like?

Salt crust on the soil and scorched, browning leaf tips. Excess soft leafy growth with poor fruit set from too much nitrogen. Leaf drop shortly after an over-strong feed. Feeding finger lime an ordinary plant food instead of a citrus-specific one is the defining mistake — it lacks the magnesium and iron citrus demand, and the leaves yellow between the veins no matter how often you feed.

Should I flush the soil of finger lime?