Question
hello i live in fort worth TX. and would like to know when do you know its time to pick watermelon and cantaloupe off the vine

Answer
The best way to tell when a cataloupe or watermelon is ripe is when the stem slips easily from the vine or the tendril above the stems completely dries. Also, for cantaloupes, once the rind turns completely tan, and the fruit is firm but not rock hard, the melon is ripe.    

There are a couple of other tricks, but ultimately it comes down to experience. One proven method is to "thump" the melon with your forefinger. If the resulting sound has a ringing or echoing sound, the melon is still too green to pick. If, however, the sound is dull, the melon is ripe. You should begin this test once the tendril (the pigtail attaching the melon to the vine) turns brown.  This is a sure sign that the melon has reached its maturity.

I hope this answered your question. Please write again if I can ever provide assistance.

Regards,

Mike