I always grow F1 female cucumbers in my greenhouse and they are never bitter. I was advised to always use female plants. Not sure if you used female seeds or not?
Hello joy s,
You can pinch pinch out the male flowers as this stops them from pollinating the female flowers. However to do this you need to be able to identify which are which. Watch Monty's video to help you identify them. As sarah mcilvenny2 says, F1 seeds are supposed to give you only female flowers, but you do need to keep an eye on them. Good luck with this summer's crop.