Four things alerted me to the reality that they probably were not garden-variety summer squash.
1) Their rate of growth was truly astonishing. I would check on them in the morning and they had grown 2 or 3" overnight!
2) They were not affected by squash beetles, who appear by magic anytime I plant regular summer or winter squashes.
3) The leaves were extraordinarily huge.
4) The vines started to creep out of the raised vegetable bed in a gleeful attempt to scramble up the mature 15ft bottlebrush (out of view on right of photo).
On the right, a photo I took of the vines this morning.
It's Calabaza, which I have grown in my garden before very successfully.
The Calabaza is a Cuban winter squash - also known as Seminole Pumpkin. It needs a lot of room to grow. Once the vines have a secure hold on a tree or fence they develop yellow flowers and then the very large and heavy fruit mature over 3-4 months. Calabaza is quite drought resistant.
A few years ago the vines almost smothered a bottlebrush and the tree started to die. When we removed the vines and the huge canopy of leaves the size of dinner plates, the sun deprived bottlebrush still took 3 to 4 months to recover.
I really hate to remove anything growing so well, especially when it's a food source. The Calabaza can be cut in half and roasted - skin up - in a shallow pan filled with water. Don't forget to remove the seeds first. Then you can scoop the flesh out and mash it with some butter. My family do not care for it though, or any variety of pumpkin or squash. So it had to go.
While I was removing the plants, I noticed that I had nematode damage on all the roots. So I'm glad I cleared them out before the fall planting schedule arrives. As you can see on the right, I covered the affected vegetable bed with black plastic to cook the nematodes. According to the USDA, regular white sugar kills nematodes, so I gave the soil a thorough dusting with sugar first. Then I watered that in and applied the plastic coating.
However a lesson also came out of this. The only reason the seeds germinated was because I had not given the compost heap enough time to break down and reach a high enough temperature. If you needs some tips on creating a great compost heap, watch this video. How To Make Compost The Easy Way
If you have the room to grow this squash, just use the seeds from a store bought squash. You don't even have to dry the seeds out. Then stand back and prepare to eat squash for 6 months! They do store well in a dry, cool place, and of course you could always give them away to a local food bank.