The versatile lemon

Article originally published by: Kiwi Gardener

You can never have too many lemons. Hannah Zwartz explains.

If I had room in the garden for just one tree, it would have to be a lemon. They have fruit full of flavour and vitamins for drinks, baking, salads and more, super-fragrant flowers, and good looks to boot.

Where I grew up in Wellington, it’s not easy to grow lemons. Originally from sub-tropical Asia, their ideal temperature is 25-30°C; they prefer well-drained loam with plenty of compost, they hate cold winds and frosts, and thrive with high humidity. You couldn’t get much further from ideal conditions than our exposed, clayey Wellington garden, but Mum found a sheltered corner and nurtured a lemon tree into production. If you live anywhere south of New Plymouth or Napier, lemons might need some nurturing – but they’re worth it.

The first step is to choose the right spot

Don’t maroon a lemon in a dry place, without protection from cold winds. They deserve a prime location with at least six hours of sun per day. Soil needs to be rich, as lemons are heavy feeders. On clay or waterlogged soil plant the tree on a mound, or in a raised bed or pot.

The beautiful flowers are highly fragrant.

Lemons are shallow rooted and the root zone needs to be well fed and moist. So add generous amounts of compost, mulch well and don’t grow anything else (including grass) too close to the trunk where roots will compete. The more you feed your lemon tree, the better it will fruit. I mulch regularly with compost and seaweed, covered with a deep layer of wood chip to stop the roots drying out.

Unless you’re in the warmest parts of the country, give lemons a sheltered corner for best results. Mature trees can handle a few degrees of frost, but young ones need winter frost protection or a frost-free pocket.

Lemons will grow successfully in large pots – the larger the better, as they hate drying out. Half-barrels are good, and the dwarf ‘flying Dragon’ rootstock is particularly suitable. Lemons in pots on a sunny patio might need daily watering, but are close at hand for picking and enjoying the sweet-smelling flowers.

Lemons are heavy feeders; yellowing leaves with green veins signify magnesium deficiency.

Pests and problems

Yellowing leaves: Leaves that turn yellow while the veins are still green indicate magnesium deficiency. Water on some Epsom Salts – about half a cup in a watering can, once or twice a year. Sequestrene does the same job.

Lemon tree borer: A very common native beetle whose grub burrows through the soft-wooded trunks of citrus trees (as well as puka, pittosporums, figs, etc.). The insects, flying around over summer, can sniff out fresh-cut tree wounds from a long distance. They lay eggs there, and the hatching larvae burrow into the wood, excreting sawdusty frass from telltale holes. These holes are the best way to attack the insect, says bugman Ruud Kleinpaste. He recommends two methods – poking in a guitar string to spear the grub (“I prefer to use a G string, but the B or the A will do”) or injecting in some kerosene, then sealing the hole with Blutak or something similar, and leaving the grub to choke.

Sometimes lemon trees become riddled with borer, causing whole branches to die as the burrowing larvae effectively ringbark the tree from the inside. Luckily lemons can handle quite hard pruning, so these branches can be taken right off. This is best done in winter to avoid the beetles sniffing out your pruning cuts – if pruning in summer, use a pruning paste.

Lemon tree borer is a common insect pest, damaging trees from the inside out.

Black sooty mould: A sign of insect infestation. Usually either aphids or scale are sucking sap and excreting honeydew, which grows the sooty mould. Deal to the insects with your chosen method (mine is Neem), then hose off the mould. Lemon foliage loves a hosedown as it provides the humidity they crave.

Vigorous, thorny growth: Sometimes appearing low on the tree, this could be rootstock and should be removed as it won’t bear fruit.

Lemon trees can sprout back from quite hard pruning, but little and often is the best tactic. Avoid masses of unproductive twiggy growth by cutting off whole branches at the trunk rather than snipping at the ends. Some trees, the ‘Meyer’ variety in particular, can bear fruit year-round.

Surplus can be used in many ways: make lemon curd or preserved lemons; lemon cake, pie, tart or dhal; squeeze and freeze juice in ice-block trays; make a hair rinse or deodorant; use half-lemons for a manicure (the pith and peel are great to clean and buff nails).

Please be aware lemon varieties will vary by store. Please speak to our Garden expert’s in-store for more information.