How to grow Lemon

Citrus × limon

The lemon is an evergreen citrus tree grown for its sour yellow fruit. It does not survive frost, so outside frost-free regions it is kept in a pot that spends winter indoors or in a greenhouse; young grafted trees start fruiting within 1–3 years.

Quick facts

Type	Fruit tree
Family	Rutaceae
Light	Full sun
Soil pH	5.5–6.5
Frost	does not tolerate frost
Sowing to harvest	730 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Planted as a young plant from a nursery while it is dormant — in early spring before the buds open, or in autumn after leaf fall.

Harvest from November to February (northern hemisphere).

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Growth	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage
Fruiting	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage; nitrogen, 56 days into the stage; nitrogen, 70 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	5…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	5…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Growth	every 14 days	—	nitrogen, at the start of the stage
Flowering	every 14 days	—	—
Fruiting	every 14 days	—	nitrogen, at the start of the stage
Harvest	every 14 days	—	—
Winter rest	every 42 days	—	—

At home

Stage	Watering	Temperature	Feeding
Growth	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage
Fruiting	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage; nitrogen, 56 days into the stage; nitrogen, 70 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Growing notes

Light

Give it the brightest spot you have, at least 6–8 hours of direct sun, such as a south or south-west window; it can stand outdoors in summer once nights stay above 10 °C.

Soil

Use a quick-draining, slightly acidic potting mix (pH 5.5–6.5) in a pot with good drainage holes; never leave the pot standing in water.

Care

Water thoroughly when the top 5–7 cm of the mix are dry, which in hot weather can mean almost daily; in winter let the surface dry partly before watering. From spring to early autumn feed every two weeks with a nitrogen-rich citrus feed with trace elements, and in winter switch to a balanced winter citrus feed. Keep it at 13–29 °C while growing and rest it at about 10–18 °C in winter; move it indoors gradually before nights drop below about 10 °C. Indoors, hand-pollinate the flowers with a soft brush. Thin branches in February and pinch back new shoots in summer.

How to tell it is ripe

The fruit has reached full size.
The skin has turned from green to a rich yellow.
Colour alone is not a reliable sign; a fully coloured lemon can still be under-ripe inside.
Taste one fruit; tasting is the only sure way to tell a citrus fruit is ripe.
Lemons do not ripen further once picked, so leave them on the tree until they taste right.
Cut the lemon off with secateurs together with a short piece of stalk, because pulling it can damage the fruit.

Sources

Figures checked against these sources.