What Makes a Cucumber Stay Small & Turn Yellow?

Poor Pollination

• Poor pollination results in malformed or small cucumbers. This typically occurs when the bee population is low or high temperatures kill the pollen before the cucumbers are properly pollinated. Sometimes rainy weather prevents adequate pollination. The resulting cucumber cannot grow to its expected size, and it turns yellow as it matures.

Poor Soil

• Low fertility sometimes causes small cucumbers that cannot grow to full size without additional nutrients in the soil. The stunted cucumbers try to mature and yellow as a sign of ripening. Side dressing with a balanced fertilizer such as 10-10-10 may revive the plant and subsequently produce healthy fruit, but the stunted cucumbers will not grow any larger. Remove them to allow new fruit to grow.

Excessive Sun Exposure

• Cucumbers that are not shaded from the sun by foliage may get sunburn and turn yellow before reaching their mature size. Remove the affected cucumbers and tuck healthy, developing cucumbers under the foliage to prevent sunburning.

Lack of Water

• Without adequate water, your plants cannot produce healthy cucumbers. Lack of water contributes to poor pollination, as well. Water your cucumbers deeply whenever the soil feels dry 1 inch below the surface of the soil.

Cultivar

• The size of a cucumber at maturity depends on the cultivar grown. Pickling cucumbers reach a length of 4 to 6 inches and cease growing. Once the full size is reached, the cucumber ripens to yellow. Slicers reach lengths of 7 to 9 inches before ripening. Some cultivars produce round, yellow cucumbers. Always check the cultivar you have planted to determine the size your cucumbers should reach at maturity before assuming growth is stunted or the cucumber is yellowing prematurely.

Seasonal Changes

• Even healthy, vigorous cucumber plants begin to produce smaller fruit as the season progresses and the plants near the end of their life cycle. Cucumbers at the end of the season may be stunted and ripen to yellow quickly. This is a normal result of aging cucumber vines.