this is a volunteer, I have never grown anything that looks remotely like this, do you know what it is and if so, when should I pick it?
Thank you in advance.
That is awesome! It looks like a neat cross between a pumpkin and a gourd or a pumpkin and a summer squash. It is nothing that is available on he market to my knowledge. It is slightly similar to the batwing pumpkin but it is much larger. I would let it grow until the tendril next to the pumpkin is dry and brown. It will be similar in shape to a jack-o-lantern type pumpkin, but it obviously has different colors. I am guessing you didn't buy those seeds and they are either from a pumpkin you bought or a pumpkin you grew but didn't hand pollinate.
Very pretty! It'll be interesting to find if it has good usable flesh.
Back in 2001 I picked up a bunch of pumpkins, off the curb, in NJ, to process for eating. One of them had a gourd like, hard shell. But the inner flesh was superb. I saved a couple of seeds and grew them out in 2006. I couldn't believe it, they came true to seed! So, now I'm growing from the second generation.