Hi Tui, I have a lime tree which has leaves going very yellow. Is it lacking iron or does it need a general fertiliser? I have applied fertiliser, it is the only one of my citrus doing this. All of my other young trees are good.
Yellowing leaves is usually a sign of a lack of magnesium in the soil. Epsom Salts helps correct magnesium deficiency, mix 30g of Epsom Salts per litre of water (approximately 2 tablespoons), per tree. Epsom Salts can be applied directly to the soil at the same rate, water in well after application. Tui Citrus food is a specially blended fertiliser for all types of citrus, Tui General Garden fertiliser is also okay to use.
A few cultural tips for limes that may help is that they love warmth and are sensitive to frost. Plant it in a sheltered sunny position. You don't say whether the tree is established or recently planted. Make sure the soil is free draining with plenty of organic compost dug into the planting hole. Apply Tui Seaweed Plant Tonic to the lime tree regularly at a rate of 30ml per 9L watering can. Seaweed helps strengthen the cell wall of the plant and protect it from temperature extremes, hot and cold. This needs to be applied around 6 weeks before frost is expected to protect from frost, it will still be of benefit to the plant if it is applied now.
The Tui Team