Signs Your Plants Are Getting Too Much Water - as part of the expert series by GeoBeats. Here is a perfect example of a plant that got over watered in the greenhouse. So, one of the tell-tale signs of a plant being overwatered is you see a lot of soggy black leaves. The soggy black leaves are definitely a sign of over-watering. The other sign of over-watering is visually, you could actually see the soil looks wet. So, in an example like this, this plant is clearly over watered. It has got the black soggy leaves and you could even squeeze the water out of the plant, which makes it an obvious sign of overwatering.