Why has my lemon tree never fruited? It's in a pot and we've had it for about four years.

Here are a few tips:

• Citrus need a warm, sunny sheltered spot protected from wind.
• Use a quality free-draining potting mix such as Tui Citrus & Fruit Mix, it contains all the essential nutrients that citrus require and feeds for up to six months.
• Plant citrus into a pot that is at least 30cm to 50cm in diameter, this gives the roots room to grow, make sure the pot has drainage holes in the bottom. It may be that the plant needs repotting into a bigger pot.
• Apply a controlled release fertiliser that is specially blended for citrus in spring and again in late summer.
• Supplementary feed from spring through to autumn with a liquid plant food such as Tui Liquid Superfood Citrus & Fruit fertiliser to keep the plant actively growing and healthy.
• Consistent watering is important. For plants in pots and containers you may need to water 2-3 times a week. If citrus dry out at the time of fruit set the fruit will drop off.
• If the plant does flower but fruit don’t set it could be a lack of pollination by bees.
• Check if there are any obvious signs of pests or disease. Ants crawling over the plant is a sure sign that there is either scale insect, mealy bug or aphids which will stunt growth.

Note: if the tree you have is a grafted variety, they take around 3-4 years to flower and fruit.