I'm trying to save zucchini seeds this year. I left one of the early fruits on the plant so it could mature. It's huge and hasn't changed in probably 6 weeks (still big and green). I thought I heard that it would change to a yellow color when it was mature. Our first frost may come tonight so I'm planning on covering the plant (leaves touching the tarp will probably still be damaged). Might the fruit be mature enough to harvest right now? Otherwise I probably only have a couple more weeks before frost protection won't work anymore.
Western Montana gardener and botanist in zone 6a according to 2012 zone update.
Gardening on lakebed sediments with 7 inch silty clay loam topsoil, 7 inch clay accumulation layer underneath, have added sand in places.
The zucchini might change color. It might not. Here's a photo of some of mine fully mature.
I recommend picking the squash rather than covering the plant. So much labor to cover, and results tend to be less than satisfactory, and this time of year the plants are shutting down anyway. You can leave the fruit at room temperature for months and the seeds will continue to mature, if they haven't already. My general attitude towards seeds, is that they are viable much earlier than we'd tend to expect. I like the fingernail test... If the skin has hardened, then I figure that so have the seeds.