How to grow lemon

Buy from a registered nursery about 1-2 months before you plant. Ask for a grafted, certified tree — one where a known fruiting lemon top has been joined onto a tough, chosen root (the rootstock).

Find the graft union: a swollen knob or scar low on the stem, where the top was joined onto the root. A grafted tree has one; a seed-grown tree does not — and a seedling fruits late and not true to type.

Ask the nursery which rootstock suits your ground. Avoid a sour-orange root where citrus tristeza virus (CTV — a virus spread by aphids that slowly kills trees on the wrong root) is about. On heavy or wet soil, ask for a root that stands wet feet and resists root rot.

Check the tree is healthy before you take it: green, even-coloured leaves, no sticky or curled shoots, no silvery leaf trails, and one straight stem.

Reject any tree with blotchy, one-sided yellow leaves — that can be citrus greening, which has no cure and will infect your whole planting. If the nursery stock looks sickly, walk away and buy elsewhere.

Choose a spot on deep, well-drained soil. Test it first: fill a knee-deep hole (about 45 cm) with water; if it has not drained away within a day, the ground stays too wet — build the soil up into a raised mound and plant on top.

Dig a hole about knee-deep and knee-wide (roughly 45 cm each way) and loosen the sides, so the young roots can push out easily.

Set the tree so the graft union sits a hand-span (about 20 cm) above the soil — never bury it. Spread the roots out, fill back with topsoil, and firm it down.

Space trees 6 to 7 strides (about 6.5 m) apart each way — a lemon grows into a big tree and must not crowd its neighbours, or the shade traps damp and feeds black spot.

Build a watering basin: a low ring of soil about a stride (1 m) across around the trunk, to hold water over the roots.

Drive in a stake and tie the young stem to it loosely, so wind cannot rock and loosen the new roots. Then water it in well.

Keep a weed-free ring at least a stride (1 m) across around the trunk, and mulch it to hold moisture — but keep the mulch off the bark.

Start shaping about a month after planting, then go over the tree again every 4-6 months through the first 3-4 years.

Pick 3-4 strong branches, spaced around the stem, to be the tree's main arms. Rub or snip off the others while they are still small.

Cut out any water shoots (fast, straight, upright shoots that shoot up but never fruit) and any dead or crossing branches.

Keep the centre open — thin out shoots growing inward, so light and air reach right through the tree. An open tree dries quickly and catches far less black spot than a dense one.

Pull off every shoot coming from below the graft union — that is the wild rootstock, not your lemon, and it will take over the tree if you leave it.

Make clean cuts close to the branch, in dry weather. Where the sun is fierce, paint big cuts or the bare trunk white to stop sunburn.

Walk to each young tree about once a month and look closely at the soft new shoots, the leaves, the stems, and the base of the trunk.

Psyllids (they spread greening): on the tender new growth, look for tiny insects that sit with their tails cocked up at an angle — a pose no other citrus insect has — plus white waxy curls and sticky honeydew (the sugary goo they leave behind). Squash them; if you keep seeing them, treat the new growth.

Greening itself: look for leaves with a blotchy, lopsided yellow mottle — yellow on one side of the mid-vein, green on the other, in no matching pattern — plus yellow shoots and small, hard, one-sided fruit. A tree with these signs cannot be cured — mark it and get advice on removing it before it infects the rest.

Leafminer: look for silvery, squiggly snail-trail tunnels inside the new leaves, which curl and pucker. It mostly just disfigures the soft growth and rarely needs spraying on a young tree.

Scale insects: look for small, still, brown or white bumps stuck on the stems and leaves, with sticky honeydew and black sooty mould. Wipe or prune off small patches.

If you find greening → mark the tree and have it removed on advice; if psyllids keep coming back → treat the new growth with a horticultural oil, soap spray, or a recommended insecticide before they spread the disease.

Water every 1-2 weeks — more often in heat or on sandy soil: fill the basin so the water soaks deep, then let the top dry a little before the next watering.

Check with a finger: water when the soil a finger-joint down (3-5 cm) is dry. Keep it moist, never waterlogged — standing water rots the roots.

Feed little and often: a small dose of nitrogen fertiliser or well-rotted manure, spread in a ring on moist soil out at the edge of the leaves (the dripline, where the feeding roots are) — not against the trunk. Your recommendation gives the amount.

Keep the mulch and weed-free ring topped up so the feed and water go to the tree, not the weeds — but keep the mulch and manure off the bark.

Keep fertiliser out of reach of children, off any food, and out of the water, and wash your hands after handling it.

From about 3 months after planting, look over each tree every 4-6 months and tidy it lightly — do not hard-prune a young tree.

Remove dead, crossing and inward-growing shoots, and any water shoots (fast, straight, unfruitful uprights).

Pull off every shoot sprouting below the graft union — that is the wild rootstock trying to take over.

Keep the centre open so light and air reach right through; a dry, airy young canopy catches far less black spot.

Walk the trees about once a month, all year round, and look over the leaves, shoots and any small fruit.

Black spot: look for small dark specks and spots on the leaves and rind, often with a pale grey centre and a dark ring — like tiny targets. It thrives in damp, crowded canopies, so where you see it, open the tree up and keep to your spray programme.

Leafminer: look for silvery snail-trail tunnels in the new leaves, which curl and twist — worst on the soft new growth.

Aphids and tristeza: look for clusters of soft green or black insects on the new shoots, curling the tips. Aphids spread citrus tristeza virus (CTV), so keep the new growth clean and squash them.

Note where the problems are worst — usually the shaded, crowded parts of the tree — and prune those areas open.

Go over each bearing tree every 2-4 months, always in dry weather.

Remove dead, crossing and inward branches and all water shoots (fast, straight, fruitless uprights), and thin the centre until you can see light through the tree.

Keep the tree to a height and width you can reach to spray and pick — head back the tallest tops.

Cut off any shoots coming from below the graft union (the wild root).

Take out low branches that let fruit touch the ground, where it picks up rot and pests.

Clear the prunings away and burn or bury them — old diseased wood and leaves left under the tree re-infect it.

Feed a compound (NPK) fertiliser every 2-3 months, splitting the year's feed into several small doses rather than one big one — your recommendation gives the amount and type for your tree.

Spread it evenly in a ring under the outer canopy (the dripline), where the feeding roots are — not against the trunk.

Feed onto moist soil and water it in, so it reaches the roots instead of gassing off or just sitting on top.

Read the leaves for hunger: yellowing between the green veins of older leaves means magnesium shortage; small, narrow, yellow-blotched new leaves mean zinc. Both are common in citrus — correct them with a foliar feed (see the flowering-stage zinc/boron spray).

Keep fertiliser off any food you will eat, out of the water, and away from children, and wash your hands afterwards.

From about two weeks before the flowers open until a month after, check the new growth on each tree every week or so — every 3-4 days in a heavy burst of new growth.

Look on the tender new shoots and flower buds for tiny psyllids sitting with their tails cocked up at an angle — a habit no other citrus insect has.

Look too for their white waxy curly tubes and sticky honeydew on the new growth, and for twisted, notched young leaves.

Act on the first sighting: knock them off and treat the new growth (a horticultural-oil or soap spray, or a recommended insecticide) — do not wait for the numbers to build.

Keep watching for the blotchy, one-sided yellow leaves of greening itself; mark and remove any tree that shows them, before psyllids carry it further.

Spray in the two weeks just before the flowers open, when the buds are showing — this beats spraying after the flowers have already set.

Mix a zinc + boron foliar feed at the rate on the label. Boron is needed only in a tiny amount — too much harms the tree — so never overdose. Your recommendation confirms the product and rate.

Spray to wet the leaves all over, in the cool of early morning or evening, not in the hot midday sun.

Spray with the wind behind you, keep it off your skin, eyes and nose, and off food and water; wash after, and respect the waiting time on the label (the pre-harvest interval — the days between spraying and safely picking) before eating any fruit.

From about two weeks after flowering right through fruit fill, check the fruit every 3-4 days.

Hang a fruit-fly trap or two in the trees and watch the catch; check the fruit for tiny sting marks and soft, sunken spots that begin to rot.

Fruit fly: a stung fruit softens, rots and drops early; cut one open and you may find small white maggots inside.

False codling moth: look for a small sunken spot or hole in the rind with crumbly droppings, and fruit that colours and drops too early with a caterpillar tunnelled inside.

Black spot: look for hard, dark, sunken target-like spots (dark ring, pale centre) on the rind, worst on the sun-exposed fruit.

Collect and bury all fallen and stung fruit twice a week — left lying, it breeds the next wave of flies and moths. Start your baits and sprays on the first stings, or the first rise in trap catches.

From two weeks after flowering through the months of fill, water every 7-10 days — more often in heat and on sandy soil.

Aim for steady, even moisture: fill the basin, let the topsoil dry a little, then water again. Avoid a long dry spell followed by a flood, which splits the fruit.

Check with a finger: water when the soil a hand-span down (about 20 cm) is dry. Keep water off the trunk and never let it stand around the roots.

Keep the mulch topped up to hold moisture between waterings.

From about two months after flowering, as the fruit sizes up, run fly control every 7-10 days until harvest — start sooner if traps or stung fruit tell you the flies have already arrived.

Hang fruit-fly traps in the trees to track numbers and catch the males.

Apply protein bait — a sweet, smelly liquid mixed with a little insecticide that lures the flies to a poisoned spot. Dab it in spots on the trunk or a few leaves (not over the whole tree), so the flies feed and die before they can sting the fruit.

Collect and bury all fallen and stung fruit twice a week — this is half the battle, because maggots in dropped fruit become next week's flies.

If you spray, cover your skin, eyes and nose, spray in the cool with the wind behind you, keep it off any fruit you will eat soon, and respect the pre-harvest interval (the waiting time on the label between spraying and safely picking). Wash afterwards.

Start the fungicide programme about two weeks after flowering (petal fall — when the petals drop and the tiny fruit forms), when the little fruit is most easily infected, and repeat every 3-4 weeks through the main fill period — your recommendation gives the product and timing.

Use a protectant fungicide (one that coats the fruit and leaves as a shield, rather than one that works from inside). Each time, spray to cover the fruit and the whole canopy, because the spots start from any unprotected patch.

Remember that an open, well-pruned tree that dries fast needs less spray — pruning and spraying work together against black spot.

Clear away fallen leaves and fruit, which carry the fungus and re-infect the tree in the rains.

Spray in the cool with the wind behind you, cover skin and eyes, keep it off food, wash after, and respect the pre-harvest interval (the waiting days on the label before you may safely pick).

Start picking from about 7 months after flowering, and go back every 2-3 weeks to take what is ready — the tree ripens its fruit over a long spread, so no single pick clears it.

Pick fruit that is full-size, heavy and juicy, with the rind turning from green toward yellow. You can also pick full-size green fruit — lemons store and colour up well off the tree (see the post-harvest task).

Clip each lemon off with secateurs or snips, close to the fruit — never pull or twist, which tears out a plug of rind and lets rot in.

Pick into a soft bag or padded basket, lay the fruit down gently, and keep it out of the sun — bruised, hot fruit rots fast.

Pick when the fruit is dry, not straight after rain or heavy dew — wet-picked fruit rots more in store. If the fruit is still hard and small, leave it — it will not fill any more once cut.

Handle gently and sort out any cut, stung or rotting fruit — one rotten lemon spoils the whole box. Keep the sound fruit cool and shaded straight after picking.

Cure the fruit for a few days in a cool, airy, shaded place — this toughens the rind and heals tiny skin nicks so it keeps longer.

Colour up green fruit if you want it yellow: hold it warm in a closed space with a little ethylene (the natural ripening gas that ripe fruit gives off — even a few ripe bananas in the room will do it) to turn the rind from green to yellow, without softening the fruit.

Store cool and humid — a cool room, shaded store or cold store keeps lemons firm and juicy for weeks to months. Do not store them airtight, and keep them away from strong smells.

Check the store now and then and pull out any fruit that starts to rot, before it spreads to the rest.