Plus, once a cucumber plant starts producing, there are cucumbers of different sizes on the plant.
Pick the yellow cucumber promptly and compost it.
Remove any yellow cucumber from the plant, because it will slow down fruit production overall.
The Spruce / Jayme Burrows
Mulching helps retain soil moisture.
Remove the yellow cucumber and increase your watering frequency.
Tip
Cucumbers grown in containers and raised beds need even more water than plants in the garden.
The Spruce / Jayme Burrows
3) Too Much Water
Too much water also causes cucumbers to turn yellow.
This happens when the soil drains poorly and it rains a lot.
You might notice rainwater puddling around the base of the plant.
The Spruce / Jayme Burrows
If its a potted plant, you might have simply overwatered the plant.
Next time before you plant, add organic matter or perlite to the soil to improve drainage.
When watering a potted cucumber, stop watering when water drips out of the drainage holes.
The Spruce / Jayme Burrows
Use a liquid high-nitrogen fertilizer such as fish emulsion to get the nutrients to the plant quickly.
Reapply it every two weeks or as recommended on the fertilizer packaging.
This way, you could fix any nutrient deficiency before the new growing season.
The fruit, which is otherwise shaded by leaves, is exposed to full sunlight, which causes yellowing.
This is like a sunburn where the chlorophyll is damaged, resulting in a yellow color.
An infection of the plant with downy mildew can have a similar effect.
The disease, which thrives in wet or humid conditions, causes the leaves to turn brown.
They look like they have been killed by frost.
Is It Safe to Eat Cucumbers That Have Turned Yellow?
It is not recommended to eat cucumbers that have turned yellow, but it’s probably safe.
It is best to discard them.
University of Delaware Cooperative Extension.
