Bitter Cucumbers

Question:

 Last year, I planted cucumbers and was disappointed. They had a bitter and odd taste to them. A neighbor suggested that they were being pollinated by the squash plants growing nearby. Will moving the squash to a different location solve this problem?

Answer:

  • The problem will not be fixed by relocating the squash plants. Squash and cucumbers can't cross-pollinate as the genetic structure of the two plants is very different.
    • Only members of the same species can interbreed. Squash will cross-pollinate with other squashes, melons, and pumpkins.
    • This brings us to the next fallacy of this old-wives tale. If the two plants could crossbreed, would it affect the current year's fruits? The answer is that this is also no. When two plants cross-pollinate, the results are unknown until you grow the saved seed the following year. This is a moot point if you plant new plants each year. Thus, cucumbers, squashes, melons, and pumpkins can grow side by side without problems. The bitterness in cucumbers is due to a naturally occurring compound called cucurbitin. All cucumber plants contain varying amounts of this compound triggered by environmental stress.
  •  Environmental stress comes from high temperatures, heavy soil that is too wet, dry, and drains poorly, low fertility, insects, and foliage diseases. Frequently, it is a combination of many of these factors.
  • However, I believe uneven or irregular watering contributes to the problem in the Bay Area. This is mainly a problem when the growing season has below-normal temperatures in the spring coupled with rapid changes in temperatures from mild to hot during the summer months.
    • Bay Area gardeners tend to water with the same frequency regardless of the temperature. Yes, we water more when it's hot, but never the less when the temperatures go below normal.
    • The other factor is soil preparation. Overall, it's pretty minimal for our adobe, clay soil. Soil amendments must be added yearly in the spring to replenish what was lost last year. So be generous with commercial or homemade compost.
    • In addition, mulching is encouraged in a vegetable garden to even out the moisture and insulate the surface roots from the sun. Adjust your watering pattern based on the weather forecast on your phone and make adjustment weekly.
  •  Also, overly mature or improperly stored cucumbers may also develop a mild bitterness; however, it's often not severe. 

NOTE: The cucurbitin is often concentrated at the stem end of the vegetable and in the light green layer under the skin of the cucumber. You can limit the bitterness by peeling cucumbers from the blossom end toward the stem end and cutting off the last inch. Ripping your peeling knife after each slice is best to avoid spreading the bitter taste.