Citrus care in summer: water, feed and pests
Summer care for lemons, oranges, mandarins and limes: regular watering for shallow roots, a late summer feed, leaf miner, stink bugs and fruit drop.
Lemons, oranges, mandarins and limes are among the most popular home fruit trees in Australia. They are tough, but summer tests them: their roots are shallow, they are hungry feeders, and several pests are at their busiest. Here is what they need from December to February.
Water: little and often isn't enough
Citrus roots sit mostly in the top 30 to 60 cm of soil, so they dry out quickly. Deep watering two or three times a week in hot weather suits most trees, more for trees in pots, which may need water daily.
- Water out to the edge of the canopy, where the feeding roots are.
- Keep the soil evenly moist. Swings between dry and wet cause fruit to split and drop.
- Mulch well, keeping it clear of the trunk, as citrus are prone to collar rot.
Feed in late summer
Citrus are hungry. A common pattern in Australia is to feed in late winter and again in late summer. Use a citrus fertiliser or well-rotted manure and compost, spread under and beyond the canopy, and water it in well. Don't feed during a heatwave.
Yellow leaves with green veins on new growth often point to iron or manganese, common in alkaline soil. Yellow blotches on older leaves often point to magnesium. A soil test before spending on fixes tells you which.
Pests to watch
- Citrus leaf miner: silvery, winding trails in new leaves, which curl and distort. Spray new growth with horticultural oil every week or two while it is soft. Older trees outgrow the damage.
- Stink bugs (bronze orange bugs and spined citrus bugs): suck on young shoots and fruit, causing fruit drop. Knock them into a bucket of soapy water. Wear eye protection, as they can squirt a stinging liquid.
- Scale and sooty mould: black film on leaves usually means scale or aphids above. Horticultural oil smothers scale.
- Aphids: on new shoots. Ladybirds and hoverflies usually catch up.
- Citrus gall wasp (in some areas): note any lumpy swellings on stems now, and prune them off in winter before the wasps emerge in spring.
Fruit drop is normal
Citrus set far more fruit than they can carry, and drop much of it in late spring and early summer. Some drop is normal. Heavy drop usually means the tree went short of water or food during fruit set.
Sunburn
Fruit and bark exposed to afternoon sun can burn. Keep a full canopy, avoid heavy pruning in summer, and paint exposed trunks of young trees with diluted white water-based paint.
The Trees n Bees care guide shows each month's care for the citrus on your property, from oil sprays for leaf miner to the late summer feed, and any of it becomes a job in one tap. A dry spell alert reminds you to water before the soil dries out.