As cucumbers grow well during warm weather, they have produced prolifically this growing season. But as it gets time to harvest, there can be a few problems that may arise.

Hot, dry weather can cause bitterness in cucumbers due to the compound cucurbitacin. Cucurbitacin is found in the leaves, stems and roots of the plant and can spread into the cucumber fruit when plants are under stress. To avoid a bitterness problem, try planting bitter-free cultivars, such as ‘Sweet Slice’ and ‘Sweet Success’. Watering cucumber plants once a week during hot, dry weather may also be helpful.

Blossom-end rot is a common problem caused by a lack of calcium in developing fruit and also may occur with tomatoes, peppers, eggplants and other cucurbits. Most Iowa soils have plenty of calcium, but lack of water to carry the calcium from the soil to developing fruit creates rotting on the blossom end. Blossom-end rot prevention tips include maintaining an even moisture supply and do not over-fertilize your plants, as excessive nitrogen inhibits calcium uptake.

Cucumbers should be harvested every two to three days while they are still immature, dark green in color, and firm. Pick cucumbers promptly as soon as they reach the proper size. Pickling cultivars should be harvested when the fruits are two to four inches long. Slicing cucumbers should be six to eight inches long and 1½ to 2 inches in diameter.

Over-ripe cucumbers will turn yellow in color and the flesh will become tough with woody seeds. Over-mature cucumbers left on the vine will also inhibit additional fruit set.

Some cucumbers, such as the round-shaped ‘Crystal Lemon’ and the heirloom ‘Poona Kheera’ from India, are actually yellow in color. Be sure to check these types frequently and harvest before they become over-mature.

Did you know? The Master Gardener program is a great way to meet new people and to grow your gardening knowledge. Training will begin August 23, apply online by at: https://mastergardenerhours.hort.iastate.edu/application-form.php or contact your local extension office for further details.

Horticulture Questions? Contact McCormick at yvonne@iastate.edu for information or advice.