Don't know what's happening to my watermelon, please help! The leaves near the center are turning yellow and it appears to be slowing working its way outward. It's getting more and more yellow each day. Details below:
Golden midget watermelon
20 inch diameter, 20 gallon container
Water every day - two gallons
Using Espoma Tomato-Tone fertilizer as instructed every week or so
Potting media is Purple Cow potting mix with coconut coir as mulch
In full sun
Located in Chicago
Pictures here: http://imgur.com/a/fQqMN
Please help, I don't want it to die! Thank you much!