watermelons

[nepeta]

I have two yellowbaby watermelons growing in my greenhouse. they don't seem to be getting much bigger now but how can I tell when they are ripe?
I know with other melons the stem starts to come away from the fruit when they are ready to eat but am not sure if this is the same for watermelons.

[nepeta]

[john_miller]

On the other side of the vine from where the stem from the fruit joins the vine you will see a 'pigtail'. When this is brown and withered the fruit will be ripe. This is the most reliable indicator that I know of.