I never had success with my cucumbers, they always start like bumper crops and then mostly nothing grows, they are always greenhouse type, since I am trying indoors. Here is probably my answer.
JB: Probably, not pruning enough of the fruit at the beginning of the growth of the plant. The plants that grow in the greenhouse are all female. They cannot produce male flowers. Regular cucumber plants produce male flowers first on several of the nodes before they produce a female flower. If they can’t produce a male flower, they produce a female flower. If we leave that on to develop, it will load the plant down with fruiting before it has developed enough to grow a good crop. That’s why we have to remove the female flowers. I prefer to remove them up to the 10th node.
The questions related to cucumbers tend to be about not producing or that the fruit is curling. If the young cucumbers start curling as they hang there then the end turns around like the end of a “J.” Then it’s either fruit overload or it could be nutritional.
One of my common sets of questions when nutrition might be a problem is, “What is the electrical conductivity (EC)? What is the PH? What is the EC in the leach? What runs off the plants compared to the strength of what is fed to the plants?” Those are indications of how the plants respond to what they’re getting. If they’re gobbling everything they can out of the solution, and there’s a big drop in the EC, then the grower should be feeding more. If it’s building up a little bit, that’s okay. If it’s building up too much, then the plant is probably struggling to get water.