The system you will be using (two plots 5 miles apart) is basically the same as I have used in recent years. You can safely grow one variety of each species, in each plot, with no special precautions... provided that your neighbors are not also growing the same species.

The pumpkins & squash are likely to be the most trouble. Most summer squash & hard-stemmed pumpkins are Cucurbita pepo. This would be my suggestion:

Since you don't know which squash varieties will succeed in that location (with its different soil, climate, pests, and diseases), take a good selection of varieties with you. Since you intend to save seed, be _sure_ none of those varieties is a hybrid (many summer squashes are). Bring enough seed with you for several plantings. The first year, grow some of them _all_, observing how they perform - but save no seed.

The following year, choose only two of the best varieties, and plant one in each of the widely-separated plots. You should be able to save seed from both safely. If you find that you want to save seed for more than two C. pepo's, repeat the process the following year with two different varieties.

Alternatively, you could grow just one variety per year in one of the plots (for seed saving) and grow as many as you wish in the other plot. You could also, as you mentioned, grow as many as you choose & use hand-pollination to save pure seed. The choice depends upon how many varieties you choose to grow, and how much effort you wish to expend.

Thanks Zeedman! So out of curiosity, if I were to take with me a C. maxima or C. moschata, would I face the same trouble as I would with another c. pepo? I found this awesome link below which mentions which is pepo, moschata, etc. I read at another site that maxima and moschata will not cross with pepo, but I'm asking to be sure-- you can't believe everything you read :)

Here is a link that might be useful: Squash/Pumpkins and their species

Nice link, Julianna, I haven't seen that one before. Both hybrid & open-pollinated squashes are pictured... however, they are not identified as hybrid or OP. That is an important distinction, since you intend to take only OP varieties with you.

For open-pollinated squash varieties _only_, there is a much more extensive squash listing (by species) in the book "Seed to Seed" by Suzanne Ashworth (which I highly recommend you take with you, considering what you are planning). If you have access to the book "Garden Seed Inventory, Sixth Edition" (published by the Seed Savers Exchange) it lists most of the OP varieties sold in the U.S., with descriptions.

The C. pepo squashes are the most widely grown, because there are so many types - including nearly all Summer squashes, most pumpkins, acorn squash, spaghetti squash, ornamental gourds, and quite a few others. They run the greatest risk of crossing, with others of their species grown nearby.

C. maxima & C. moschata will not cross with C. pepo under normal conditions. You could grow one of each in each plot, and still save seed. Even if your plots are only 2 miles apart (I mistakenly said "5 miles apart" in my previous post) the chances of a cross between the two plots is very small; if there are other pollen sources between them (such as flowers), the odds are almost infinitesimal.

There are some references (which others may quote) that say inter-species crossing is possible in rare cases... but I & many others have not experienced any. I don't plant all three mixed together, however; I grow the different species on opposite sides of the garden, with other crops between. Not sure if this really makes a difference... but as long as it works, I'll keep doing it. ;-)

Thanks again, Zeedman! I was thinking I could do that-- plant the different species with other things inbetween. This is great news :) I'm taking seed-saving distances in mind right now, and probably will spend some time this year looking into specing and figuring out exactly what I *can* have in our space. I mean I could grow a field of veggies, but if they all cross and I can't use the seed, what's the point, you know? I'd love to be able to keep and try to grow some old favorites of mine. They've got some great heirlooms of their own, but I am partial to some things that culturally just aren't popular-- not because of growing conditions, just because of culture.

The issue with the Levant is rainfall and climate matches Southern CA patterns very much, but rain is all they have.. so you cistern up and basically make it all year on a winter rainy season. This works fine-- they grow everything you can imagine... but if you have a bad year (or 10) you have to look at your seed supplies. I wanted to grow fresh seed each year in case of a bad year or two or three-- to keep as close to a back-up as possible.

Thank you so much for the reccomendation of "Seed to Seed"-- it looks like exactly what I needed, and I found it on Overstock.com for 37% off cover price :)