Lemon

Hybrid origins

This citrus is of hybrid origin: it is linked to citron and bitter orange, and northeastern India is considered its place of origin. It is not a typical naturally occurring species: the plant has long developed in cultivation, separately from its ancestral forms.

Citrus plants generally have a complex history of hybridization. This is why the boundaries between species, cultivars, and cultivated forms in the genus Citrus are not always clear: many fruit-bearing citrus plants descend from several ancestral lineages.

The Ukrainian name meaning “lemon tree” refers to its woody growth habit: indoors, it is not an herbaceous plant but a small evergreen tree with a canopy, shoots, leaves, and true fruit.

Canopy and leaf structure

In natural conditions, members of the genus Citrus are evergreen shrubs or trees, often with thorny shoots. In a pot, growth is limited by the size of the root system, but the plant still develops woody shoots and needs consistent light across its entire canopy.

The leaf blade is leathery and green, glossy on top and duller underneath. Leaves are 10-15 cm long and 5-8 cm wide, with a short petiole measuring 1-1.8 cm.

• evergreen canopy
• leathery leaf blade
• smooth leaf edge
• short petiole
• essential oil glands

Hold a leaf up to the light and small translucent dots become visible. These are essential oil cavities, which give the leaves their characteristic citrus scent.

Flowers and the hesperidium

The flowers grow in the leaf axils, singly or in pairs, with a five-part corolla measuring 2-3 cm across. The petals are white or slightly cream-colored and may have a pink or purple tinge on the outside.

The citrus fruit is a hesperidium, a special type of berry with a thick fruit wall and juicy internal segments. The fruit is 6-9 cm long and 4-6 cm in diameter, pale yellow, with a bumpy or pitted rind.

Inside the fruit are 8-10 spongy chambers. The juicy flesh consists of enlarged endocarp cells; these store juice and form the characteristic sour flesh.

Light and temperature

The plant needs bright light, but direct midday sun on a south-facing windowsill in summer can overheat the leaves and pot. For indoor growing, a southeast-facing window or a well-lit spot with shade during the hottest hours is often chosen.

Too little light shows up as smaller, paler new leaves, weak shoots, and few flowers. In winter, when daylight drops to 7-8 hours, the plant may need supplemental lighting.

A comfortable range during the growing period is +18…+25 °C. Avoid sharp daily fluctuations during flowering: the difference between day and night temperatures should be no greater than 6 °C.

Watering, humidity, and potting mix

Citrus roots need air as much as water: in constantly wet potting mix, they suffocate, and the leaves and shoots quickly deteriorate.

Water when the top layer of potting mix has dried. In cooler winter conditions, letting the top 2-3 cm dry can serve as a guide; after watering thoroughly, empty the saucer after 5 minutes.

• loose texture
• good water drainage
• good aeration
• neutral pH of 6.5-7.0
• drainage in the pot

Dry air during the heating season increases stress on the leaves. At high temperatures, washing dust off the leaves, using a tray of damp expanded clay pebbles, and gently misting with clean, soft water can help.

Yellowing, leaf drop, and pests

Yellowing leaves are most often linked to watering practices, too little light, dry air, or depleted potting mix. Sometimes a magnesium or iron deficiency is a separate issue, so watering more often does not always solve the problem.

Sudden leaf drop usually signals stress: moving the plant, a draft, a sharp temperature change, or roots that are too dry or too wet. After repotting, the plant may also temporarily shed some leaves if its roots were disturbed.

• spider mites
• scale insects
• fungal infections

Spider mites tend to become more active in dry air, so increasing humidity and misting regularly reduce the risk of their spread. If scale insects appear, inspect the shoots and the undersides of the leaves.

Repotting, pruning, and cuttings

Repot young plants every 1-2 years and mature plants about every 3-4 years. Choose a pot only slightly larger than the previous one: an excessive volume of potting mix takes longer to dry and increases the risk of waterlogging.

Prune in late winter or the first days of spring. Shaping the canopy matters for more than appearance: the amount of light reaching the branches affects the strength of new growth, bud formation, and the ability to retain fruit.

Indoors, the plant is propagated mainly from cuttings taken from a healthy, fruit-bearing plant. Take a cutting almost 10 cm long with 2-3 developed buds.