I can't seem to get darker green with the three plants I've got.




They get enough water, and I am not over watering them. I'm in Fort Worth, Tx. It's hot here.

they normally yellow as they mature.
there are types that start out yellow.

not sure which you have, but those look like they matured on the vine to me... personally, I'd be thinking about trying to save the seeds from the pretty one...

The cucumber on the right of the picture looks like a textbook image for "poor pollination". You need to attract pollinators to your plants or, failing that, pollinate them by hand. It's a dirty job but someone's got to do it.

The one of the left looks like a Honey or one of its hybrids, nothing to worry about if it's what you bought.