Yellow cucumber?

Why do cucumber skins turn yellow?

From tiny swells behind star-shaped flowers to fully grown veggies, cucumbers spend most of their lives wearing a snug green skin. But when they over ripen their green color can disappear, sometimes revealing a deep yellow that borders on orange. Overripe cukes no longer need to harness energy from the sun and will break down green-colored chlorophyll to recycle the nutrients. Trees do the same thing when they pull chlorophyll from their leaves in the fall. Just as vanishing chlorophyll reveals reds, oranges and yellows in leaves, this cucumber is showing us the gold below the green. 

Can you eat a yellow cucumber?

You can! Though, brace yourself because it may not be your best cucumber-eating experience. As cucumbers age and the chemistry in their cells shifts, they may develop off flavors. Additionally, overripe cukes may dry out and have a more rubbery texture. And their seeds will enlarge and toughen.

“This tends to happen later in the summer and the seeds grow like crazy,” said Penelope Perkins-Veazie, a horticultural sciences professor at North Carolina State University. “So you have these giant seeds and an overripe cucumber, and then you don’t want to eat them, because all you’re eating is seeds.”

The two cucumbers in the image below came from the same plant in a backyard garden. I ate both. The golden one certainly was less tasty than the greener one, though I still enjoyed it. The golden one had a slightly harsher flavor and I noticed larger seeds, though they didn’t bother me much. It may not have been that overripe yet. 

Gardeners: Harvest your cucumbers quickly to avoid yellowing

A cucumber vine can only support so many cucumbers at a time. So if you let an overripe cucumber linger, you could be stealing resources from younger cukes. Cucumbers mature quickly, so you need to be on top of your cucumber harvesting game. 

On commercial farms, growers can harvest one to three pounds of cucumbers per week from each plant during the peak harvest period, according to an overview of cucumber production from the Food and Drug Administration and the Western Institute for Food Safety and Security at the University of California Davis. During a 12-week harvest, farmers can pick as much as 20 to 25 pounds per plant. 

If you’re a home grower at the end of the season Better Homes & Gardens notes you could let the cucumbers linger on the vine and then harvest the seeds for next year’s garden. 

Other causes of yellow cucumbers

Cucumbers could also turn yellow if they’re not getting proper water, nutrition or pollination while growing. In those cases you’ll probably see that all of the cukes on the vine were affected, not just some. And you might also see dried up, undersized or curved cukes.

Disease and insects can also cause yellowing, though those afflictions will probably come with other more jarring symptoms. 

Cucumbers can yellow during extended storage too; that’s more likely what’s happening with any yellowing cucumbers you purchase at the store. If they were harvested too late, kept too warm during storage or exposed to ethylene, a ripening gas given off by other produce, they could yellow. Some types of produce, particularly bananas, avocados and tomatoes, emit particularly high levels of ethylene, so smart produce distributors and home cooks keep those commodities far away from cucumbers. 

Some cucumber varieties are bred for a yellow color. So if you’re eating “lemon” or “silver slicers” or other such varieties, the yellow is part of the package and nothing to worry about. That said, they’re usually a pale yellow when ripe and turn a darker yellow when overripe, according to Better Homes & Gardens. The magazine also notes that yellow varieties are less prone to bitterness as they mature. 

A yellow patch is normal on a cucumber grown on the ground

Cucumbers, like watermelons, often have a yellow “ground spot.” This is the part of the cuke that was on the ground while it was growing. That yellow marks the area where the sun couldn’t reach; so to conserve resources, the cucumber withdrew chlorophyll from the “ground spot.” Healthy, perfectly ripe cucumbers have ground spots–they’re never anything to worry about. And plenty of cucumbers are grown on trellises and don’t have ground spots at all.

Thanks to Doug G. of Falls Church, Va. for sharing his garden cucumbers with us!