Today, I experienced something very common, but very frustrating. A bitter cucumber. I went into my greenhouse to discover the biggest cucumbers I’ve ever managed to grow. Feeling very smug with myself, I headed indoors to share the (literal) fuits of my labour, only to find that the cucumber was so bitter it was inedible near the stem end – though absolutely delightful in the middle.
I know that this is something that can happen, but I wanted to understand more about it and how I could avoid this happening to the other cucumbers that are yet to grown on my cucumber plants. Cue the research music!
Cucumbers are part of the Cucurbit (Cucurbitaceae) family, which also includes courgettes, melons, squashes and pumpkins. They produce a substance called cucurbitacin, which makes the plant taste horrid to herbivores to save itself from being eaten. This is usually only in the stems, leaves and roots, but can sometimes move to the fruit under certain circumstances – hence, the bitter flavour. In my research, I was surprised to find so many people asking if eating the bitter cucumbers is toxic – they’re so disgusting, it hadn’t occurred to me to keep on eating!
The circumstances under which cucurbitacin moves to the fruits tend to be due to either pollination or stress. Let’s start with pollination.
Older varieties of cucumber produced male and female plants, while some new hybrids are female only (though they can produce male flowers when they’re stressed). The female flowers are the ones that have a tiny fruit behind them, while the males do not, just like a courgette. If you have a variety that has both male and female flowers, you’ll need to remove the male flowers to avoid pollination, as this can cause bitterness in the fruits. This year, I’m growing Telegraph cucumbers – a traditional variety, named after the telegraph when it was a new invention – so it’s quite possible that my bitter cucumber was caused by pollination.
Meanwhile, stress can be caused to a cucumber in a number of different ways. Conditions that are too hot or too cold can have an effect, as can big fluctuations in temperature. It could also be a lack of water or routing watering (i.e. you let it go dry and then flood it), or of nutrients. In summary, they’re delicate flowers! My cucumbers have, I’m sure, been exposed to fluctuations in temperature, due to the ever changing weather recently. I also have to admit that my watering regime this week has been patchy at best – I always find it more difficult to remember to water when it’s been raining! You can see that I’ve not been consistently watering by the irregular shape of some of the fruits.
With all this in mind, I’ve now started my ‘consistency is key for cucumbers’ campaign in the greenhouse, beginning today with a good water and some nourishment from a seaweed feed. Tomorrow, I go on the attack, looking for male flowers to remove (there’s a feminism joke in there somewhere, I’m sure, I just can’t find it).
Fingers crossed for some good cucumber news coming your way soon!