Plant Doctor Archive

Diminishing grapefruit

THE grapefruit in our garden, which has cropped well in past years, has only a few tiny fruit this year. The tree is healthy, fed spring and autumn and shows no sign of disease or stress. What can I do to ensure it fruits well next year?

THIS is a tricky one. There are a lot of things which, individually or in combination, could cause this problem, but assuming the tree flowered well in early summer I believe the most likely reason to be summer drought causing premature fruit drop.

It sounds as if you're feeding the tree sufficiently, but be careful not to ovedo it, as too much fertiliser could aggravate the effects of water stress. Try to make sure there's plenty of moisture in the soil throughout summer - apply plenty of mulch in late winter or spring while the soil is moist and water deeply once or twice a week if necessary.

If there's the risk of exposure to strong wind during flowering (which could affect pollination) and during the first stages of fruit formation, it might pay to provide some sort of shelter, if practicable.

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