Cross-pollinating cucumbers, to cut a long story short, won’t actually harm your crop, but it will change it, and if you intend to save seeds you need to take some serious precautions to make sure you know exactly what you’re growing next year. In some cases, cross-pollination is actually pretty essential for cucumbers to crop successfully.
Fundamentally, whether you can grow different cucumber varieties together depends on what you’re aiming for.
All gardeners are guilty of gluttony to some extent, always wanting more, and never truly wanting to limit what we grow. I’m just as guilty of it as anybody else, spending far more time than I should scrolling through seed websites looking for my next obsession. This year, it’s melons. Last year it was soft fruit. The year before, it was cucumbers.
Cross-pollinating cucumbers: the basics
Cross-pollinating cucumbers can affect your crop, very slightly, in that gherkins will pollinate burpless cucumber, burpless cucumbers can pollinate telegraph cucumbers, and so on.
In my experience though, I have never had such a problem with cross-pollination that the crop has been unusable, or noticeably different from expectations.
Because cucumbers rely on sight to attract pollinators the best practice is to manually pollinate them, and most European and American pollinators are primarily scent seekers.
A healthy population of bees in the garden will naturally pollinate cucumbers, but it’s still safest to seek out male flowers, and brush a paintbrush onto their pollen, then onto a female flower’s stigma. Doing this will stop cross-pollination anyway because once a newly opened flower is pollinated it can’t be pollinated again.
While that’s achievable for fluent cucumber growers, spotting male and female flowers can be a pain for newcomers – but is relatively easy. Female flowers have a small fruit behind the flower before the bud opens, while male plants have thin leggy props behind the flower.
Gynoecious cucumbers
Pollination is absolutely essential for almost every fruit to produce crops, and while most cucumbers have male and female flowers, many are what are known as gynoecious (meaning they host almost entirely female flowers).
When a male flower attracts a pollinator (typically bees, wasps, or hoverflies) they rub pollen from the anther, which sits at the end of the flower’s stamen. That pollen is then carried to female flowers, and as the insects try to access the enthralling nectar at the base of the flower they rub pollen on the stigma. Grains of pollen then travel down to the ovule, fertilizing the flower. The fruit is the protective container for the seeds as they mature and the ovule expands.
Many plants have flowers that are capable of self-pollination, like horse chestnuts and roses. These are hermaphroditic. Most plants have both male and female flowers though, and it’s quite rare to find solely male or solely female plants in the wild.
Gynoecious cucumbers have been bred for one reason and one reason alone: to produce more fruit, especially in greenhouse conditions. But, that comes with a very specific problem in that they often fail to pollinate so actually need to be planted along with similar varieties in order to produce fruit.
This is why, with every pack of gynoecious seeds, about 10% of seeds will be an open-pollinated variety that grows male flowers. These male flowers provide just enough pollen to pollinate the female flowers of your gynoecious seed crop.
Saving cucumber seeds
If you plan to save cucumber seeds, cross-pollination is an issue, and should really be prevented at all costs, but, with a bit of preparation, you can ease your anxiety by manually pollinating a few select flowers early on.
To manually pollinate cucumbers for seed saving you’ll need some red twine (red will stand out and hold its colour later in the season) and a paintbrush.
Start by identifying the female flowers by the fruits behind the buds. Before the bud opens, tie a small piece of red twine behind the immature fruit to mark it. As soon as the flowers start to open, brush a small paintbrush against the pollen of the male flower, and apply the pollen directly onto the stigma of the female flowers. Gently close the flowers over so bees don’t pollinate them that day, and within a few hours, that plant will have carried the pollen to its ovules and begun producing fertilized fruits.
- Note: A day before they open, the papery yellow petals will start slowly unfurling, but it can take a few days to fully open depending on the weather.
When the fruit has fully developed and completely ripened on the plant, cut it off, scoop out the seeds and dry them on paper towels. When dry, seal them into a seed envelope, and they should keep until next year.
FAQs
Can you plant different cucumbers together?
Cucumbers of all types can be planted together safely, with a slight risk of increased bitterness in heirloom varieties. Most hybrid or F1 cucumber varieties actually benefit from being planted together with other cucumber varieties.
Do cucumbers cross-pollinate with each other?
Cucumbers and gherkins are part of the same plant family and other than slight differences in their fruit share the same basic DNA. They are completely capable of cross-pollinating and the results will be different to the parent plants.
Do cucumbers cross-pollinate with courgettes?
While it might seem logical that plants of the same family can cross-pollinate – it’s like a house cat breeding with a lion. There’s just so much evolution between the two that they aren’t capable of hosting each other’s pollen, so the pollen from a cucumber won’t register if introduced to a female courgette flower, and vice versa.
How far apart should cucumbers be planted?
Most cucumber varieties are happiest planted about 1ft apart, but if you’re short on space they will tolerate closer planting, with up to three in a large pot trained up a teepee. The closest we have ever successfully grown them was four to a pot, at around 6” apart.
Conclusion
While some cucumbers can become slightly bitter if pollinated by other varieties, it’s usually pickling cucumbers that are affected in that way, and the bitterness is counteracted by the pickling process, so in my humble, and possibly contentious opinion, growing cucumbers together is worth the risk.
Last year we grew telegraph cucumbers and cucamelons in the same greenhouse, with two pots of gherkins just outside the door, and had no issues when growing different cucumber varieties together.
So don’t be afraid of experimenting a little bit, and if you’re ever worried about bitterness, remember that the pickling process takes care of that for you.
