I am growing a few cucumber plants in a raised bed. I find that each plant produces a number of flowers and only one of the flowers turns into a cucumber and the rest of them dry up/wither. After I pick the cucumber, the same thing happens and only one of the flowers survives. Is that the expected behavior? Does the cucumber take up took many plant resources that it does not allow other flowers to convert to a cucumber?
No a single plant can produce many cucumbers at once. It mostly depends on how long the cucumber vine as able to grow before flowering.
The first flower is usually male, the ones that follow are the females and what produce the fruit.
Generally, no, a cucumber vine should produce several cucumbers.
I don't know that this would help but I'm trying hand pollination with some of my vegetables this year. I'm wondering if this might help you. With my tomatoes, I just give the branches that have flowers a gentle shake every other day and I did fairly well with them considering this was my first attempt.