Here’s how to ease your hot weather garden problems – St George News


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CHARACTERISTIC – Poor flowering and form or lack of fruit on tomatoes, peppers and squash may be due to the weather, not your gardening skills. Temperature extremes can interfere with flowering and fruit set of these and other vegetables in your garden.

Deformed fruit and other problems may be the result of temperatures below 55°F, location and date not specified | Photo courtesy of, St. George News

We are waiting and looking forward to tasting that first red ripe tomato. It is certainly frustrating to see the flowers drop or the plant fail to set fruit. Tomatoes thrive in warm, sunny conditions; but temperature extremes can prevent fruiting, cause misshapen fruit, or reduce crop size.

When daytime temperatures exceed 90 degrees Fahrenheit and nighttime temperatures remain above 70 degrees Fahrenheit flower drop and poor fruit development may occur. Combine that with low humidity and the pollen is not viable. In hot, humid conditions, the pollen is too sticky and does not move from the male part to the female part of the flower. Without pollination, the flowers will not be fertilized and the fruits will not develop.

Cool weather can lead to poor fruit set. Nighttime temperatures below the optimum of 59 to 68 degrees Fahrenheit will reduce the amount and viability of pollen produced by the plant. Less viable pollen means fewer fruits will form. Cooler temperatures below 55 degrees Fahrenheit can lead to distorted fruit and catfacing. Fortunately, the malformed fruit is still tasty and safe to eat.

Temperature extremes also impact pepper productivity. When temperatures soar to 95 degrees Fahrenheit or higher, pollen is sterile and flowers may drop. Small fruits may also drop from the plant during these periods of heat. Pepper plants also experience poor fruit set when nighttime temperatures drop below 60 degrees Fahrenheit or exceed 75 degrees Fahrenheit.

Stock image of tomatoes, location and date not specified | Photo courtesy of USU Extension, St. George News

Tomatoes and peppers aren’t the only vegetables affected by extreme temperatures. Eggplants, a close relative of tomatoes and peppers, do not produce fruit until nighttime temperatures exceed 55 degrees Fahrenheit. Beans stop blooming or flowers die when temperatures exceed 85 degrees Fahrenheit.

The flowering of squash and cucumber plants is also influenced by temperature and other environmental factors. These plants produce separate male and female flowers. Male flowers usually appear first and only when both male and female flowers are present can pollination, fertilization and fruit production take place.

Research has found that cool temperatures, sunlight and shorter days encourage the production of female flowers while male flowers are more prolific in warmer temperatures, less sunlight and close spacing. The flowering of squash and cucumbers is also impacted by nitrogen fertilization. Too much can prevent the formation of female flowers while too little can reduce the number of male flowers.

The easiest solution is to wait for optimal temperatures and proper humidity levels to return. Once this happens, the plants will start producing fruit.

If low weather-related productivity is an annual problem, consider planting more heat-tolerant varieties, adjust planting times, and find more suitable growing locations.

When harvest is delayed, extend the season with row covers. These fabrics allow sunlight, air and water to pass through while trapping heat around the plants. Simply cover the plants loosely and anchor the edges with rocks, boards or landscape stapes when frost is expected. You can leave the fabric in place for the rest of the year. Simply lift it up to harvest and secure the fabric when finished.

If this summer’s weather leaves you disappointed with the harvest, remember there’s always next year.

Copyright Melinda Myers, LLC, all rights reserved.


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