Plant Doctor Archive

Fruit drop on citrus tree

I'VE had a lime tree in a pot for about two years now. Each year it develops flowers and fruit, but when the fruit reach about a centimetre in size, they drop off. The photo shows one small fruit beside a normal-sized lemon. Any idea what is wrong?

FRUIT drop such as you describe can be caused by poor pollination, cold wind or lack of water during the early stages of fruit development. However, limes can be tricky at the best of times, even in the garden. It's not unknown for them to grow well yet produce few fruit. I know of a lime orchard where some trees bear lots of fruit while others growing alongside are barren, yet there's no obvious reason to explain the difference.

Of all the citrus, limes are the least cold-hardy. While the Tahitian lime (Citrus x latifolia) tolerates more cold than the Mexican lime (Citrus x aurantiifolia), they both grow best in a warm, sheltered, frost-free spot. To encourage fruit production, shelter your plant from cold winds, particularly when flowering and during the early stages of fruit development, and don't allow the mix to dry out excessively. You could mix water retention granules like Saturaid into the mix to help retain moisture.

A good supply of nutrients during spring and summer is also essential to encourage healthy new growth that will bear flowers and (hopefully) fruit later. You can buy specific citrus fertilisers, but a general slow release fertiliser or regular doses of liquid feed such as Nitrosol or Thrive is fine for plants in containers. They need plenty of nutrients, so err on the high side of the recommended application rates. You may also have to repot your lime, as they eventually need a container of around 50-60cm in diameter to grow and fruit well.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.