Hello flash drought, goodbye fruit. Here’s why 2022 was a bad year for tomatoes in KC

Was your tomato harvest less fruitful this summer? You were not alone, as gardeners across the metro area report a poor harvest. The issue was our constantly changing weather patterns, which made it hard for tomatoes to grow and set fruit for a bountiful harvest.

The tomato woes plagued us from the start of the season. Mid-May through early June brought a very chilly and wet start to the growing season. Tomatoes are a warm-season crop. Soil temperatures lower than 65 degrees reduce root development. Early root development gives the plants the support needed for good summer growth and fruiting.

Cool soil temperatures combined with excess moisture also stressed developing roots. Wet soil conditions slow root development and in some cases lead to rot, which is very difficult for the plant to overcome. The slow start to the season was just the first setback.

Next came the flash drought. Not familiar with that term? You aren’t alone. Flash drought is a rapid change of below-normal precipitation combined with abnormally high temperatures. We quickly reversed from cool and wet to hot and dry. This rapid change intensifies stress on plants.

Tomato plants impacted by the slow cool spring start had not developed a strong root system to support the top growth. Plants wilted during the heat of the day, further slowing growth, and reduced flower bud development.

As the summer progressed, the heat interfered with fruit set and compounded the problems. While tomatoes grow best during warm, sunny summer days, they do have temperature limits. When daytime temperatures exceed 85 degrees and nighttime temps remain above 70 degrees, fruit set diminishes.

Tomato flowers are perfect, having both male and female parts in the same flower. Pollen is usually transmitted by wind or insects from the male to the female ovary. High temperatures cause the pollen to dry and become tacky. It is not viable by the time it reaches the ovary and pollination fails. The result is no fruit set. Conversely, temperatures below 55 degrees also result in poor pollination and fruit set.

Moisture is the other major factor that influences how fruit sets. Dry soil conditions stress plant growth. Remember: Plants initially had poor spring root development, which means they were less able to cope with the flash drought conditions.

Low soil moisture sets up a battle in the plant between supporting developing fruit or setting more flower buds. Usually, the plant defaults to early fruit set at the expense of flower buds. This reduces production later in summer. Uneven moisture also decreases fruit development. A rapid influx of water, either from rain or watering, causes cracking in the fruit and reduces the quality.

What is a gardener to do? We cannot control the weather. This leaves us few options except good cultural practices. Some basic steps:

▪ Plant recommended varieties.

▪ Plant at the correct time, in mid-May.

▪ Provide consistent moisture during the growing season.

▪ Mulch to keep soils cooler and retain moisture.

▪ Eliminate other stressors, such as weeds.

Lastly, and most importantly, be the eternal optimist. There is always the hope that 2023 will bring better growing conditions and a bumper crop of vine-ripe tasty tomatoes.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Have a question for him or other university extension experts? Email them to garden.help@jocogov.org.

This story was originally published September 16, 2022 at 5:00 AM.