Experts and BHG readers answer.
Cucumber blossom end rot
Garden doctor: my inground cucumber plants are gorgeous with lots of blooms but cukes dry up when about 1" long even though I give them calcium supplements. Help!!! Zone 8
Your cucumbers may not be getting pollinated. If the blossoms aren't pollinated, the fruits abort at a very small stage. You could try to hand pollinate them by using an artist's brush, taking pollen from the male flowers (without a swollen base), and transferring some pollen to the female blooms (those with a swollen stem under the flower.