Thanks for writing. The general rule is to pick melons when the green, curly tendril on the stem nearest the the melon turns brown and dry; when the surface color of the fruit goes from shiny to dull; when you can't easily puncture the rink with your thumbnail; and when the bottom of the melon changes from greenish to yellowy.
There are several factors that influence how quickly tomatoes ripen. For example, they'll ripen more slowly in cool, cloudy weather than in warm, bright weather. So you may need to be patient with them.
---Justin, Senior Garden Editor, BHG.com "