Gardening Q&A: A reader’s cucumbers aren’t producing. Blame the hotter, drier weather.

Q. I have five hills, three plants each, of Straight Eight cucumbers from Wyatt-Quarles Seed Co. The vines are healthy with blooms, but only a small amount of produce. In the past, with the same amount of plants, I could pick a peck about twice a week. This year, I got only one or two cucumbers per hill. String beans, squash and tomatoes in the same space did really well. What do you think is going on? — Thomas Robbins, Newport News

A. First, a refresher on cucumber sex. Many cucumber varieties, such as your Straight Eight, an heirloom and AAS (All-America Selection) in 1935, are monoecious. This means that separate male and female flowers are produced on the same plant. Ordinarily, this type fits the needs of most homeowners, delivering a more-or-less continual supply of fruits throughout the growing season.

As you may know, cucumbers are not self-pollinating. Unlike your string beans and tomatoes, they must rely on insects for pollination (the transfer of pollen from stamens to pistils). The fact that both sexes are present on the same plant in such monoecious varieties serves to facilitate this transfer. Their close Cucurbitaceae relatives, the squashes and gourds, require insect pollinators as well.

Some other cucumber hybrids are gynoecious, meaning the plant produces only female flowers. Thus, pollen must be transported from a male parent to the plant with female flowers. In production systems, a variety with male flowers is interplanted throughout the crop to provide the pollen source. A ratio of about 9-to-1 female to male plants is required for proper pollination. The fruiting period in this type is more concentrated, which helps mechanical harvesting of the crop. It is used primarily by commercial producers but can be useful for homeowners who can their produce.

Last, some cucumber varieties are parthenocarpic: They can produce fruit without pollination. The fruits produce few to no seeds and are best grown indoors to prevent fertilization from other cucumbers within distance of pollinators.

In the case of monoecious cucumbers, such as yours, clusters of male flowers typically form a week or so before the female flowers (those with the swollen base). This timeline helps ensure that pollen is available, and pollinators are active, when female flowers appear. Timing is everything with reproduction!

Now, your situation. Things seemed to be going smoothly, and then boom: The dog days of summer hit. You probably noticed just about everything in the garden going into slow motion. With cucumbers, higher temperatures generally foster male flower development, while cooler weather increases female flowers. Heat of 90-degree days and 70-plus-degree nights can cause female flowers to abort, as can dry spells. Optimum plant nutrition can be tricky: Too much nitrogen will promote vegetative growth at the expense of flowering, and low nutrition levels can inhibit female flowers’ production. Abundant female flowers, but no fruit, most likely points to the lack of pollinators.

In a follow-up email, you indicated that you kept your plants fertilized and well-watered and that your neighbor has bees. It was not confirmed, but I will assume that you have six or more hours of good sunlight each day. Good — those boxes checked.

But we appear to be in a new normal with environmental conditions that can be detrimental to physiological processes in many crops. Hot days, warm nights and periodic droughts disrupt processes like fruit set and development, and seed germination.

How do we adapt to this new normal?

Next season you might consider successive plantings of one variety, or planting varieties with different maturity times, to help ensure that some plants are reproductive when the weather is favorable. Be on the lookout for heat-tolerant varieties. Also, consider planting other flowering plants in your garden that will help attract your neighbor's bees over to visit. Always a good idea.

And one more thing

Here's a reminder about Saturday's fall gardening festival held by the Virginia Beach Master Gardeners. It runs from 10 a.m. to 3 p.m. at the Hampton Roads Agricultural Research and Extension Center, 1444 Diamond Springs Road, Virginia Beach. The event will feature a plant sale, free demonstrations, a bake sale, garden tours and much more. Visit vbmg.org for the latest information.

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