Your lemon tree leaves may be turning yellow for one or more of the following reasons. I also present the solutions to these issues.

Over-watering and under-watering create yellow leaves

Both over-watering and under-watering your lemon tree result in the same symptom – yellow leaves. If you also have little or no new growth and your flowers and fruits are falling off, you’re probably under-watering. If the soil has become heavy and has mould, and the main stem of the tree is becoming soft, that’s due to over-watering.

Gardening experts present mixed advice about watering your lemon tree but here is what they agree on:

• If possible, use lukewarm rainwater. If you must use tap water, let it stand for 24 hours (for the chlorine to evaporate) before using it.
• Water much more in the summer months than in winter time.
• Don’t waterlog the soil; let the excess water run away through the drainage holes at the bottom of the pot.
• Be mindful of the material of the pot the lemon tree is in; terracotta pots dry out quite fast.
• Water liberally in the summer and sparingly in the winter. Overwatering in winter is a common problem.

When to water in the summer is where the disagreements come in. The advice ranges from several times a week to once a week. They say to let some of the soil dry out before watering again. You need to experiment with your own lemon plant to see what keeps it happy.

There’s the same disagreement for watering in the winter. The range here seems to be from once every 10 or so days to just once a month.  It’s OK if the top of the soil dries out a little, but you don’t want the plant to experience drought conditions. This will traumatise it.

Low temperatures

Even when they’re in their winter, dormant state, lemon trees like to have some warmth. The general rule is to bring them indoors when the night-time temperature falls to 10°C. Lemon trees can tolerate slightly lower temperatures but not for long. Ensure that your lemon tree is in a warm environment. If you need to keep it in a cooler place, wrap it up in horticultural fleece for its protection.

Draughts

Draughts are generally both windy and cold and lemon trees don’t tolerate either state well. They need to be in a protected environment even outdoors, with plenty of sunshine. Check whether your tree has been exposed to inclement weather or is in a wind tunnel on your patio or deck. As for being indoors, close all doors and windows to keep a comfy environment for the tree.

Lack of nutrients keep the leaves yellow

Yellow lemon tree leaves also may indicate that the tree doesn’t have enough energy to make sufficient chlorophyll to colour the leaves green. As with any other citrus trees, lemon trees become hungry for the correct nutrients that they may not be getting from the soil or compost that you used to pot them in.

To combat this, frequently apply a high nitrogen citrus feed in the summer. This is the growth and fruit production period when the plant needs most of its energy. Once every two months should be enough in the summer switching to once every three months in the winter. Though, this really depends on the type of fertiliser you use, so read the instructions on the bottle or box.

Stay in tune with your lemon tree by reading my other articles about what problems you may encounter. Check out Why is my lemon tree losing leaves? and Why is my lemon tree sticky?