They look good, just a bit light green.
I grow cucumbers in an Earthbox and fertilize the soil pre-planting with 10-10-10 and side-dress it about 5 weeks laater.
As a beginner, I quickly learned about powdery mildew (PM),: it's not IF your cukes willl get it but WHEN!! Powdery mildew is spread through the air: it's EVERYWHERE!! It is a real pain!!!
Lower production, misshapen cucumbers, plants die a slow death
I now plant PM resistant varieties and start a spraying regimen as soon ass they start climbing. I use a rotation of 2 fungicides that declare they control PM: one is always Bonide Copper Fungicide (it's organic approved).