Master Gardeners: What’s wrong with my cucumbers? | Home and Garden

Do you wonder why some years your cucumbers have low yields but you’re not quite sure what you did wrong? It might not be you. It could be the finicky “dating and mating habits” of cucumbers that are causing the problems. Arm yourself with a little information and most of your cucumber problems will vanish!

Most cucumbers are monoecious in their methods of reproduction, which means they have both male and female blossoms on the same plant. The first blossoms to appear in the spring will be mostly male. Since only female blossoms produce cucumbers, the result is almost no fruits. Given a couple of weeks, the ratio of male to female blossoms will be almost equal, but that won’t necessarily result in more cucumbers.

For good fruit production, both male and female blossoms must be open and ready for pollination at the same time. The blooms open in the morning just as pollinators are arriving in the garden. Pollinator insects are imperative because cucumber pollen is so sticky that almost no pollen blows around on the wind.

You can encourage more pollinator visits, and therefore more fruits, by planting blooming flowers among your cucumbers. Keep in mind that not all flowers are bee magnets; marigolds, carnations and trumpet-like blooms probably won’t get the job done. Instead, try flowers such as bee balm, coneflower, salvia, Russian sage and other blooming plants that bees love.

Another option is to plant blooming annual cover crops like mustard, clover and buckwheat. They are easy to plant alongside your cucumbers, are not invasive, and will increase the number of fruits.

There are a few special hybridized varieties of gynoecious and/or parthenocarpic cucumbers that were originally bred to meet the needs of commercial growers. Gynoecious varieties have only female flowers. More female flowers means more fruits. They must have at least a few monoecious cucumbers planted among them (for the male blooms), and lots of pollinator insects, to achieve good pollination.

Parthenocarpic varieties produce fruit without the need of pollination. Varieties that have the qualities of both gyneocious and parthenocarpic will have the highest yields without the need for male blooms or pollinator insects. Sweet Success, Socrates, Tyria, Katrina and Excelsior are examples of such varieties, and are available to home gardeners from Johnny’s Seeds and Territorial Seeds.

There are also environmental conditions that may cause problems with low yields. Cucumber blossoms are very sensitive to insect damage, overcrowding and low light conditions, all of which will result in fewer female blossoms and fruits. Temperatures above 86 degree result in more male blossoms, but below 60 degrees will result in more female blooms. Like many heat-loving crops, cucumbers want ideal conditions. When conditions are less than perfect, your cucumbers will survive, but they will let you know just how miserable they are with low yields.

You can eliminate most of these problems by starting cucumbers from seeds and growing indoors until nighttime temperatures remain above 60 degrees; covering with light-colored shade cloth when daytime temperatures are above 86 degrees; growing blooming flowers; and avoiding overcrowding. Making small changes in the varieties you choose, and the environment you provide, will go a long way toward growing a bumper crop of cucumbers.