The younger, the better - but of course you don't want to pick them too small, because it would take too many to make enough for dinner. They start out light yellow colored, then turn dark yellow - when left on the vine too long. About 6" long is just right. I ususally wait til the blossom falls off. Here's a couple of pics.

Not ready to pick...
{{gwi:84139}}

Ready to pick....
{{gwi:84140}}

Thanks, I think I may have left that big one too long as the color is changing from light to dark yellow. I'll be sure to get the others sooner.

Yeah....they're kinda like okra - you really have to keep your eye on them.

EG

Cathy, next year try some crookneck squash (like the ones in Engineeredgarden's photos). I think you'll agree they have the best taste!

Also, if you've been having a lot of rain the squash will get big fast without getting tough/overly mature. If you're not having a lot of rains you're better off harvesting the squash a little small. The squash will be very smooth and light yellow-green in color when too young; mellow in color with some bumps in the skin when mature; and dark yellow in color with a "warty" flesh and tough outer shell when overly mature. Remove the old ones as they will slow production on your vines. My dogs like to eat the old squash. I will occasionally let one old squash mature and save the seeds (Don't do this if it could cross with a winter squash variety though. Crosses of yellow to zucchini create a nice summer squash though).

"Cathy, next year try some crookneck squash (like the ones in Engineeredgarden's photos). I think you'll agree they have the best taste!"

Absolutely!

Jim

Good advice there, don't let a single squash grow to maturity or the plant slows down dramatically. Invariably one will get hidden on you so be diligent and really search it out. Apparently when one matures the plant has "done it's job" and laziness sets in.