I am almost always at a loss about yellow leaves signaling too little or too much water. The accompanying pic of a cucumber and Impatiens (both in containers) is what sometimes happens (although I have other cucs and Impatiens in the same kind of containers that are very green.
When I find a plant like this, is it best to let it dry more or add water? And when in doubt, what's the most ideal thing to do.
My gut feel looking at your pictures is over rather than under watering especially since the soil at least around the cucumber still looks wet. The way to figure this out is to stick your finger down in the soil an inch or two and see if it feels moist there. If it doesn't then it needs water, but if it still feels moist then hold off. Many people just look at the top of the soil and water if it looks dry, but in many cases there is still plenty of moisture just below the surface, so if you water it will be too much.
So a related question about potting up...
If a plant is a bit over watered or the soil that it's being transplant it to is moist, do you water it anyway when repotting. This is probably a really stupid question but i have this unshakable belief tat when you transplant, you water.
If the plant is in wet soil now and you're putting it into new soil that's also wet I would would not add additional water, especially if you think the plant was being overwatered to begin with. If I'm repotting a plant that I suspect has been overwatered, I'll actually try and get rid of as much of the old wet soil as possible, then when you put it into the new soil you can treat it as you normally would (wouldn't hurt to add a pinch of peroxide to your water, or water with chamomile tea, both of those can counteract any fungus that was starting to grow in the roots.)
