Lemon tree in the home: yellowing leaves, leaf drop – causes and what to do

The potted lemon tree has been one of the most popular plants of recent years – and one that generates the most questions too. The two most common complaints: the leaves turn yellow, or the tree suddenly starts dropping them. The two symptoms have different causes – and fortunately both are very treatable.

Yellowing leaves: iron is almost always the key

If the veins on the lemon's leaves stay green but the leaf blade yellows – starting on the young, upper leaves – that's iron deficiency (chlorosis). Citrus plants are particularly sensitive to it, and Hungarian tap water makes it worse: hard, limy water alkalizes the potting medium, and at high pH the dissolution of iron stops – even though it is present, the plant cannot access it.

The solution stands on two legs. First, water with rested water or rainwater if you can. Second, replenish iron in an immediately absorbable, chelated form: Garden Citrus nutrient solution contains fast-absorbing iron chelate – applied weekly from spring to autumn, the foliage turns visibly darker, glossier green within 2–3 weeks, and fruit set becomes more stable too.

Leaf drop: this is how the lemon signals stress

A lemon tree punishes environmental change with leaf drop. The most common triggers: a sudden change of location (e.g. moving it into the warm apartment in autumn), drafts, overwatering, and the dry air of the heating season. The good news: a healthy lemon can regrow a substantial part of its foliage once you remove the stress factor.

The most important rules: move it gradually in autumn (first a shadier outdoor spot, then a cool interior), choose a bright and cool (8–15 °C) place for overwintering – the warm living room + little winter light combination is the classic leaf-dropper – and in winter water sparingly and give no nutrient solution at all.

The lemon's annual rhythm in brief

In spring, feeding starts when it's moved outside (weekly); in summer, generous watering + weekly feeding; in autumn, gradual moving indoors and stopping the feeding; in winter, a bright, cool rest. Keep this rhythm and the lemon tree will give more flowers and ripe fruit year after year.

If your other houseplants are yellowing too, here's the diagnosis map for quickly identifying the symptoms.