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CRACKED TOMATOES AND LACK OF VEGGIES DUE TO HOT WEATHER

GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written July 30, 2015

CRACKED TOMATOES AND LACK OF VEGGIES DUE TO HOT WEATHER

We had a brief respite from the hot weather this past week, but now it is back. I am hoping that my garden tomatoes will have set more fruit during the cooler weather. I have been able to start harvesting a few ripe tomatoes, but alas many of these tomatoes are cracked.

Cracked Tomatoes: After a long wait for ripe tomatoes, it is disappointing that many have radial cracks or splits in the skin starting at the stem. This occurs because the flesh of the fruit grows faster than the skin. Temperatures over 90 degrees or temperatures fluctuating widely between day and night can lead to cracking. It also can be attributed to heavy pruning when staking tomatoes. This exposes the fruit to light and increases the temperature of the fruit.

Uneven watering, fluctuating between very dry to very wet soil, can also give rise to tomato cracks. Heavy nitrogen fertilization causes very fast vine growth, also causing more fruit to crack.

Finally, some varieties are more prone to cracking. A number of the heirloom varieties, like Brandywine, are notorious for their tendency to crack. That is one of the reasons why modern hybrids were developed. For example, Burpee developed their hybrid Brandy Boy to have the same great taste of Brandywine without the problems, including cracking, associated with growing this heirloom.

The problem with cracked tomatoes is that the cracks in the skin make it easy for secondary fungi and bacteria to infect the fruit. The appearance of mold, extremely soft fruit, or liquid leaking from the tomato are sure signs of infection. Discard them. You can eat cracked fruit that are not infected, but do so quickly because they will not last long.

Blossom Drop: Astute veggie gardeners have noted the lack of beans on their bean plants and attributed it to the heat. When temperatures climb well above 90 degrees, beans and peas will drop their flowers without setting fruit. The same often happens with tomatoes and peppers too. The reason for “blossom drop” and the lack of fruit involves pollination and the subsequent fertilization of the embryo in the ovary within the flower.

You might think the reason for this is that bees are not active in the garden when temperatures are above 100 degrees, but beans, peas, tomatoes, and peppers are self-pollinating and thus do not depend on bees or other insects to enable pollination and fertilization. However, these self-pollinating flowers do need wind or insects to shake the pollen from a male part of the flower (anther) onto a female part of the flower (stigma).

What about the veggies that do require an assist from bees and other pollinating insects? Fruit production of cucumbers, melons, and squash seems to slow in hot weather too. Aborted or misshapen fruit are because bees are not very active in the hot weather and because pollen does not remain viable for very long.

We can not do anything about the hot weather, but we can reduce plant stress and minimize cracking and blossom drop by keeping the garden soil evenly moist, mulching to cool the soil and conserve moisture, and not applying excessive amounts of nitrogen fertilizer. It’s also a good idea to provide bees with some moisture. Turn a bird bath or large pot saucer into a bee bath by filling it with coarse gravel or river rock and adding water. The stones are used as perches, so the bees will drown in the open water.

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