Plant Doctor Archive

Tomatoes won't fruit

I HAVE three varieties of tomatoes, one is setting fruit no trouble, but the other two only set one or two fruit low down on the plant. The rest of the flowers don't come to anything. I've tried spraying them with fruit set, but they just die and fall off. All the plants are healthy and I've sprayed regularly with copper spray and also Target for whitefly. I had a similar problem last year, but it seems worse this season. There also seems to be fewer female flowers on cucumbers, but my potatoes, cabbages, cauliflowers and beans are doing well.

LOTS of gardeners have reported similar problems this year. In general, tomatoes are particularly susceptible to temperature fluctuations, though some varieties are much more tolerant than others. Periods when temperatures drop in spring or get very high in summer can cause poor fruit set. The tomato plants may grow quite happily, but the extremes of temperature affect fruit set.

Obviously one of the varieties you are growing is more tolerant than the others in your conditions, so the best thing is for you to stick to growing that one in the future.

Other factors that may contribute to the problem include water and fertiliser. Try to maintain relatively even soil moisture - don't allow it to dry out for long periods. And don't go overboard with high nitrogen fertilisers. Tomatoes need good quantities of phosphorous and potassium in conjunction with nitrogen for best results.

Cucumbers need relatively warm conditions also, while potato, cabbage, caulis and beans are more cold tolerant, so it comes as no surprise that they are doing well, for the present. The situation might be reversed, however, in the heat of summer.

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