Why Are My Cucumbers Turning Yellow?

Ah, cucumbers. That gorgeous, juicy summer vegetable (is is a fruit? Or a vegetable? No one knows – and to be honest most people don’t care either!) Cucumbers are such a huge part of the summer months; whether they’re in salads or Pimm’s or both – we love them! Growing (and also pickling) your own cucumbers is surprisingly rewarding. You get a lot of harvest for just a few plants, and you can decide whether to enjoy them in a salad or a cocktail. But if you have grown your own cucumbers you may find yourself asking, why are my cucumbers turning yellow?

Well, I’m here here to answer this for you.

Types of cucumber

Types of cucumber

There are a large variety of different cucumber plants that you can buy; some are more suitable for growing indoors, some prefer the outside weather. Some are climbers; some are trailers.

If you have a small space in which to grow your cucumbers, a climbing variety may work best – you can get a great yield and they won’t take up as much ground space.

If you have a large allotment or garden with lots of room, you may be happy with one of the sprawling, ground covering cucumbers.

Whatever type of growing habitat you have, you can find a cucumber that suits it.

Why are my cucumbers turning yellow

Cucumbers take between 50 and 70 days after planting to produce their best crops. A ripe cucumber is considered to be when it is bright to dark green, a good size, with firm flesh.

If you notice your cucumbers taking on a yellowy tinge, you should harvest them right away – it is a sign that they are becoming overripe.

The green colour of the skin is produced by Chlorophyll, which fades from the skin as the cucumber ripens too far, so yellow cucumbers tell you that you are leaving them too long on the plant.

When cucumbers start to turn yellow, they also start to taste bitter, and the seeds may have grown to unpleasant size inside, so you should always keep an eye on your plants and pick them before they change colour.

If your cucumbers are still small and obviously not ripe, the yellowing can be caused by other issues. A virus, a nutrient imbalance, or overwatering, can all contribute to a change in the skin pigment of you cukes.

You can, of course, buy cucumbers from cultivars that are meant to be yellow, so if you are growing this type then ignore all the above advice!

Additional tips for growing cucumbers

You can choose to grow your cucumber plants from seed, or buy them as small plants from a garden centre. Once the little plants are established, the general growing method is the same.

  • If you have a heated greenhouse, you can plant seeds as early as mid February; if you have an unheated greenhouse or you are planting outside then you should wait until April.
  • Start the seeds out in small pots, and plant them 1cm deep, on their sides.
  • If you are planting seeds directly outside, sow them in May or early June, and cover the soil with fleece or a cloche to keep the seeds warm enough.
  • For growing cucumbers in a greenhouse, transfer the young plants into their final bed of good potting compost in late March to late May (earlier if you have a heated greenhouse, later if your greenhouse is unheated).
  • Train the main stem of the plant up a vertical pole or wire, and pinch out the top when it reaches the roof.
  • Keep the humidity high by watering the floor, and keep the compost moist.
  • For growing outside, plant out your seedlings in early June, into good soft soil that has had some well rotted compost added to it.
  • After your plant has developed seven leaves, pinch out the growing tip. The same goes for side shoots that do not develop flowers – seven leaves is the magic number.
  • Keep the soil around them well watered, but do not water directly onto the plant as this can damage the leaves.
  • For both types of growing, harvest the cucumbers when they reach between 6 and 8 inches long and have a uniform green colour and a firm texture.

This is a great, comprehensive video covering everything you need to know about growing your own cucumbers:

Final words

Cucumbers are an easy and very rewarding crop to grow. They produce well, and fast, and you can do a lot with the finished product – eating them straight from the plant, adding to salads, pickling or fermenting – the list goes on.

Just make sure that you pick them before they go yellow, for the best results!

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