Yellow leaves can indicate a wide range of ailments, such as this strawberry plant’s suspected iron deficiency. (Photo: Scot Nelson/Flickr)

Gardening is supposed be a relaxing hobby, but even the greenest thumbs see red sometimes. It might be due to fruit-stealing squirrels or earth-moving moles, but one of the most common causes of gardener angst is the sight of a tomato cage, bean fence or cucumber row draped in sickly yellow. Read more.