Pruning a finger lime tree helps get healthy, tasty fruits year after year. It also protects this delicious but vulnerable citrus from diseases and pests. Here is how to prune your Australian finger lime.
Key finger lime pruning facts
Season – after harvest (autumn)
How often – yearly
Main concern – suckers, distance to ground
Watch for – gall wasp swells
Make it a regular task visit your finger lime with secateurs, ideally monthly. Pruning a little at a time is easier on the tree than a single heavy pruning every year.
Ideal shape for a finger lime tree
Three important facts guide the pruning shape your tree should have:
- Finger lime fruits are hand-picked from the tree.
- Sun helps fruits mature.
- Air circulation reduces diseases and pests.
- Clear trunk up to knee-height (18 inches or 45 cm). If grafted, make sure nothing sprouts from under the graft joint.
- Four to six main branches, evenly spread in all directions at about waist height. Usually the main trunk is nipped off at about 2-3 feet or 60-90 cm height.
- Secondary branches form a canopy shaped like a flat dome.
- In time, a mature, 15-year old tree would be kept 8-10 feet (2.5-3 meters) wide and 6 to 8 feet tall (2 to 2.5 meters). It might take a decade to grow that large.
- Finger lime is very thorny, with fragile fruits. Branches should be thinned for the tree to be somewhat “see-through”.
Best is to circle around the tree every month to trim any shoots or branches that don’t fit into this shape. Bring thick gloves with you as the thorns are sharp.
When to start pruning finger lime
Start pruning your finger lime early on.
- Pruning as early as year 2 or 3 will form the tree without much effort. Citrus wood is hard, so pruning while small is easier.
- Finger lime, if unpruned, will grow into a random thicket of thorns. It will be difficult to correct, and impossible to harvest fruit.
- Once the tip has grown to 2-3 feet high (60-90 cm), you can start selecting and favoring the structural branches.
Steps to prune finger lime
Australian finger lime doesn’t like extreme pruning. Never remove more than a third of the tree in one go. Always keep some live branches at the tip of structural branches to make sure sap circulates.
What to consider when pruning finger lime
Structural branches – as horizontal as possible, evenly fanning out from the trunk in all directions. Mark them with a yarn or loose tag for the first few years.
Secondary branches – keep one or two that are the most horizontal at the tip of each structural branch.
- These will extend the structural branch in the following years.
- If two branches cross or touch each other, remove the one that’s the most upright.
- Remove any branches that are growing back inwards to the inside of the tree or towards the trunk or center.
Remove these: Inwards – Crossing – Upwards. As in, “I see you, ICU!”
Suckers – Remove all shoots that appear straight from the trunk. You can keep one if you need to create a new structural branch, but make sure it sprouted above the graft joint.
Skirting – The “skirt” of the tree is how low the branches reach. Cut any branch that hovers lower than knee-height (2 feet or 60cm).
Thinning – This aims to reduce the density of the tree canopy. In particularly dense spots that block out light and air, remove one in four or one in three secondary branches. A breeze should filter through the tree and not run around it. Sunlight should land on branches in the middle of the tree.
Dead wood – cut dead wood back to the nearest joint. Cut small twigs and scraggly growth off from main branches, too.
Pests – If ever you notice swelling along a branch, check for gall wasps. Cut out and burn or suffocate contaminated branches in a black sack set for days in hot sun. Skirting reduces insects and fungal diseases. Thinning spreads out pest insects and makes predator insects more effective (especially against thrips, for instance).
Structural pruning after the harvest
Wait until after the harvest to perform most of the pruning, especially if you’re “catching up”.
- This is simply because new flowers haven’t formed yet: you won’t be compromising the harvest.
During the rest of the year, you can perform follow-up pruning as often as you wish. Check and adjust the shape every month to avoid heavy pruning.
Smart tip about pruning finger lime
Snip off thorns near young fruit. It’ll keep the fruits safe from stabbing on windy days.
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Young growth by Kim & Forest Starr under © CC BY 4.0
Finger lime silhouette by Rosalyn & Gaspard Lorthiois, own work
New growth on finger lime by Kim & Forest Starr under © CC BY 4.0