1 Answer

Color is a Good Indicator
Chances are that if your pumpkin is orange all the way around, your pumpkin is ripe. But on the other hand, a pumpkin does not need to be all the way orange to be ripe. Some pumpkins are ripe when they are still completely green. When you are ready to harvest a pumpkin, use other ways to double check whether it is ripe or not.

Give Them a Thump
Another way how to tell when pumpkins are ripe is to give the pumpkin a good thump or a slap. If the pumpkin sounds hollow, that the pumpkin is ripe and ready to be picked.

The Skin is Hard
The skin of a pumpkin will be hard when the pumpkin is ripe. Use a fingernail and gently try to puncture the pumpkin’s skin. If the skin dents but does not puncture, the pumpkin is ready to pick.

The Stem is Hard
When the stem above the pumpkin in question starts to turn hard, the pumpkin is ready for picking. 

http://www.gardeningknowhow.com/edible/vegetables/pumpkin/how-to-tell-when-pumpkins-are-ripe.htm