How to grow healthy lemon trees

The lemon tree is ubiquitous in Australia but citrus can get a bunch of different pests.

Lemon trees are a backyard favourite but are also popular with pests.

It’s a running joke among garden experts that they’re asked more questions about lemon trees than anything else. That might be because the lemon tree is ubiquitous in Australia but also because citrus can get a bunch of different pests.

Every home garden should have a lemon tree. Apart from the obvious fruit benefits they have glossy leaves, the fragrance of the white blossom is intoxicating, and they’re small enough to fit into most gardens or grow in a pot. The fruit stay on the tree for a long time when ripe, so you’ll usually have a lemon when you need one.

‘Eureka’ is the family favourite because it produces fruit most of the year, has few seeds and is thornless. It can reach 3-4m but it’s sensible to keep trees pruned to a height that allows you to easily maintain the tree and pick fruit. ‘Lisbon’ is a similar size but thorny, with excellent quality fruit and better cold tolerance. Its main crop is in winter and spring with a smaller summer crop.

‘Meyer’ has less acidic round fruit with a smooth, thin rind. Its prolific main crop is early winter but it can fruit through the year. Being frost hardy it’s the best choice for cold climates and as a smaller, 2m tree it’s a great choice for pots. All varieties are available grafted onto dwarfing rootstocks that limit the size of the tree without affecting fruit size.

Like all citrus, lemons grow best in a north-facing position with at least six hours of direct sun a day and protection from strong winds. They hate wet feet so if your soil is not well drained, plant on a mound. They’re rather crudely called “gross feeders” as they love food and water, so enrich the soil with plenty of organic matter before planting and feed them every month using one of the pelletised chook poo fertilisers. The best ones include additional trace elements such as boron and zinc that citrus need.

Newly planted trees can direct their energy into growing a strong framework if you remove developing fruit in the first two years. Regularly pinch out the tips of elongating shoots to encourage branching. Prune lemon trees in late winter to early spring each year, shortening lanky stems, removing congested or crossing branches and maintaining a manageable size. Old, overgrown or neglected trees can be rejuvenated with severe pruning (“skeletonising”), leaving bare bones and no foliage. The tree won’t produce fruit for a year or so while it regrows foliage. Lemons can also be trained to grow flat against a sunny wall.

PESTS 101

Citrus leaf miner: silvery trails on new leaves. Spray with PestOil or Eco-Oil weekly during growth surges or use traps.

Scales: brown, black, white or pink dots that scrape off with a fingernail. Use oil sprays. Aphids: soft sap-suckers on new shoots. Wait for ladybirds; hose off; use pyrethrum.

Sooty mould: black powder on honeydew from scales and aphids. Treat the pests.

Stink bugs: Knock into a bucket of soapy water wearing eye protection – they squirt stinky, caustic liquid. Fruit fly: maggots in fruit or rot around site of stings on skin. Use organic baits and attractants.

Gall wasp: lumps on branches. Prune or slice off side of gall to expose and kill larvae inside.

Our Ficus ‘Burgundy’ grows well in our apartment but why have the leaves lost their purple colour and become green? Grace Greenhalgh, by email

Plants with leaf colours other than green are most intensely colourful in bright sun and tend to lose that colouring in shade. Your plant needs a much brighter spot.

How should I prune my leggy evergreen frangipani? It’s eight years old, in a pot. Bel Ward, Sydney

Several evergreen frangipani species from the tropics can be briefly deciduous in the sub-tropics and fully deciduous in cooler areas. Plumeria obtusa or Singapore frangipani has leaves with rounded tips and petals. P. pudica has unusual, long, spoon-shaped leaves and upright, multi-branched form. Prune below where you want new shoots to emerge. Specialists Sacred Garden Frangipanis recommend pruning in autumn after flowering and applying fungicide powder on the cuts. Try propagating the pruned pieces; dry in a cool spot for a couple of weeks before planting into sandy potting mix.

I’m a first-time spinach grower. Is there a way to keep snails away without using baits? Debbie Terret, by email

Hand-picking snails after rain or by torchlight at night is effective and safe. Barriers of crushed eggshells, lime or sawdust prevent snails and slugs crossing them. Copper barrier tape is very effective in wet or dry weather and is long-lasting. A shallow dish of beer dregs will attract and drown snails.

Send your questions to: [e-mail] or Helen Young, PO Box 3098, Willoughby North, NSW 2068. Website: helenyoung.com.au. The best question for October wins Wallgarden’s Multi-hang Vertical Garden Kit with 20 modules, worth $138.