Q: What makes my cucumbers so bitter?
A: Cucumber stems, leaves and roots are naturally bitter, to stave off the attack of insects. In fact, the bitter chemical has a name: cucurbitacin. When a cucumber plant is stressed, the chemical can spread to the green skin of the fruit.
One way to avoid having bitter cucumber in your salad is to peel them in a certain way: slice the peel away from the blossom end towards the stem end of the cuke. Quickly rinse the knife or peeler between cuts. This technique prevents cucurbitacin, which concentrates in the stem end, from being spread over the rest of the cucumber.
Anything that reduces stress on your garden cucumber plants will help reduce bitterness. Mulch your plants, do not allow the soil to dry between waterings and don’t over-fertilize in hot weather.