We can't always have everything. ;-)

Seriously, research published in Annals of Botany prove that "melo has the potential for a mixed mating system with high dependence on insect-mediated pollination" rather than self-pollination. So 50-75 feet wouldn't be nearly enough for any sort of guarantee of better than approx. 50/50. Of course there are all sorts of other variables involved as well that might improve your odds but there is no way to know for sure. All you can do is work with what you have and hope for the best. Or you can bag blooms and hand pollinate.

Dave

Annals of Botany 104(6):1129-39 · September 2009

That wasn't the answer I wanted at all! :) Thank you very much for the response though, it's tough to make the call as to what I want to do now. I suppose I could live with 50/50 and then double plant next year. For the melo I'm doing Armenian cukes and a kajari melon, I can't remember how different they look when they're small. If they're different enough and I recognize early which have cross bred then I shouldn't have much of a problem. I'm more worried they won't look all that different until they're about to produce at which point I'll have wasted a good chunk of growing time. As for the squash, I wanted to do spaghetti, summer and tatume or delicata. Maybe I could plant them under a cover and hand pollinate the tatume and spaghetti for a month before uncovering them, leave the summer squash uncovered and only collect seeds from the first few squashes. I'm hoping that gives me a higher percentage of true to type seeds.

I grew several types of squash in close proximity last year, not thinking about saving seeds at the time. I'm going to plant the seeds next year anyway as an experiment. If I remember I'll post the results.

P.S. Last year the best squash, hands down, was the Sweet Meat winter squash. It was the best squash I ever ate. The whole family agreed with me. This year I think I'll just plant that and spaghetti squash, which is quite different (but I love it too.)

PPS If it's possible to stagger the plantings so that the plants are blooming at different times, you can avoid the cross-pollination too. You need a pretty long growing season to do that , and/or maybe could snip off new blossoms after a few squash have set??

The mystery hybrid squash resulting from cross-pollination might be good, anyway. You never know.

Squash seeds can last, properly stored for 5 years...so you can have 5 varieties, and rotate them out, year to year...you aren't really limited to just variety. Also...different species won't cross...so look your varieties up...it is possible to plant several squash side by side without them crossing...and there is also vertical growing if space is a problem, look into that, too.