How to Grow a Kakadu Plum

Sun

Full sun produces the heaviest fruit crop. Eight hours of direct sun daily is the target outdoors. Container plants brought outdoors for summer should sit in the brightest spot available, and indoor winter homes need a south-facing window or grow light.

Warmth

Keep the plant above 50°F year-round. Brief drops below 45°F damage the leaves, and frost can kill young trees outright. In zones 9 and colder, move container plants indoors well before the first cool nights of fall.

Daytime temperatures between 75°F and 95°F suit Kakadu Plum best. The plant tolerates hot dry summers in zone 10 well, since its native habitat sees regular heat.

Drainage

Kakadu Plum needs sharp drainage. The roots rot quickly in soggy soil. Dig a one-foot test hole and fill it with water. If it drains within a few hours, the spot is fine. If water sits overnight, build a raised mound or grow in a container with multiple drainage holes.

Soil and space

Loose, sandy or loamy soil with plenty of organic matter works well in the ground. Containers want a tropical-fruit potting mix amended with extra perlite for drainage. Outdoors, give a mature tree 10 to 15 feet of clear space, since it grows 15 to 25 feet tall and almost as wide.

Watering

Water deeply once a week through the first two growing seasons to help establishment. After that, Kakadu Plum is fairly drought-tolerant in zones 10 through 12 and gets by on rainfall in most years.

Through extended summer dry spells, a deep weekly soak keeps the tree productive. Container plants dry out faster and need checking every 2 to 3 days in summer. Reduce winter watering by half for both in-ground and potted trees, since the tree slows during the cooler months.

Feeding

Feed lightly with a balanced fertilizer in early spring as new growth starts. Heavy nitrogen pushes leafy growth at the expense of fruit, so skip lawn fertilizer near the tree.

A second light feeding in early summer helps container plants, since nutrients leach out with each watering. Stop feeding entirely by midsummer so the tree can build energy reserves for the cooler months.

When to prune

Prune in late winter just before new growth pushes in spring. Avoid pruning in late summer or fall, since cuts made then may not heal before cooler weather arrives.

What to cut

Remove dead, broken, or crossing branches at the trunk. Cut back any shoots emerging from below the graft union (if the tree was grafted) flush with the trunk, since these rootstock suckers do not produce true Kakadu Plum fruit.

Light tip-pruning during the growing season helps maintain shape on container plants. Avoid hard pruning of a mature tree all at once, since heavy removal stresses the plant and reduces the next crop.

Keeping a container plant small

Container plants benefit from light tip-pinching during the growing season to keep them compact. Pinch growing tips back by an inch when shoots reach the desired length. The plant branches out from the cut and stays at a manageable size for indoor winter quarters.

When to pick

Pick when the fruit has reached full size and the skin softens slightly to gentle finger pressure. Most fruits stay pale green even at full ripeness, with some varieties showing a yellow blush. Taste a few first, since underripe fruit tastes harsh and astringent.

How to pick

Twist gently at the stem and ripe fruit releases easily. For higher branches, use a long-handled pole picker or shake the branch lightly onto a sheet spread below the tree. Pick every few days during the ripening window, since fruit drops naturally once fully ripe.

Using and storing

Fresh fruit eats raw straight off the tree but most growers preserve the harvest. Common uses include jams, syrups, vinegars, and dried-and-powdered fruit for adding to smoothies or sauces. The vitamin C survives drying well, which is the main reason the fruit gets processed.

Fresh fruit keeps about a week in the refrigerator. Frozen whole, the fruit holds for a year and is excellent for jams and syrups made off-season.

Leaf drop after cool weather

Brief exposure to temperatures below 50°F triggers leaf drop. Move container plants to a warmer spot immediately. New leaves regrow once temperatures rise. Prevent recurrence by keeping the plant well above 50°F year-round.

Wilting with wet soil

Root rot from overwatering or poor drainage. Pull the plant out of the pot, trim away any soft brown rotten roots with sharp scissors, repot in fresh well-drained mix, and water sparingly until new growth appears. Adjust the watering schedule to let the top inch of mix dry between drinks.

Fruit dropping before ripe

Young trees commonly drop most of their fruit in the first couple of fruiting years as the tree decides how much it can support, which is normal. In an established tree, heavy fruit drop usually means uneven watering or sudden temperature swings. Water consistently and shelter the plant from cold drafts.

Maggots in ripe fruit

Fruit fly larvae burrow into ripening fruit and ruin the harvest. Hang fruit fly traps starting six weeks before harvest. Pick fruit slightly underripe and let it finish indoors to avoid the worst of the fly damage. Clean up fallen fruit promptly to break the breeding cycle.

Bumps on stems with sticky residue

Scale insects feeding on sap and excreting a sugary residue that grows black sooty mold. Wipe individual scales off with a cotton swab dipped in rubbing alcohol. Heavier infestations respond to horticultural oil applied to thorough coverage in late winter.

Squiggly trails through the leaves

Leaf miners are larvae feeding inside the leaf tissue. Damage looks alarming but rarely kills the tree. Pick off heavily mined leaves and discard them away from the garden. A spinosad spray timed to the early summer adult flight reduces the next generation.

Yellow leaves with green veins

Iron or other micronutrient deficiency, common in container plants where nutrients have leached out. Apply a fertilizer with micronutrients or a chelated iron foliar spray for fast correction. Check soil drainage if the problem recurs.

No flowers on a young tree

Kakadu Plum takes four to five years from planting to first reliable flowering. A young tree producing only leaves is normal. Be patient through the establishment years and avoid heavy nitrogen feeding, which delays flowering further.