To the plant, pollination is pollination. To the gardener who wants particular results (such as wanting to keep an heirloom variety pure), cross-pollination (cross-breeding) is something to avoid. To a grower or scientist who is trying to create a new variety, cross-pollination is desirable. It's all on your point of view. Like Dave said, some varieties are very genetically stable, like his Nantes carrots. Others, like curcubits, are notorious for cross-pollinating. If you're growing certain kinds of decorative gourds, and zucchini or other squashes, insects will cross-pollinate them very easily, and if you saved the seeds from your wonderful zucchini and planted them, they could end up being something almost unrecognizable and tasteless. "Does cross pollination always create a hybrid?" Yes and no. Technically, every pollinated plant is producing a hybrid, because every plant from every seed has a tiny, microscopic difference from the plant next to it, although it is, for most purposes, the same. Only cuttings, cloned or tissue-cultured plants are exactly the same as the parent stock. Plants labeled 'hybrids' have been crossed from plants with noticeably different qualities. If you crossed two of these 'hybrids', they would most likely revert back to the qualities of one or the other of the 'parents'. Granny Smith apples came from crabapples. If you planted a Granny Smith seed and nutured it for several years, you would probably end up with some sort of crabapple or similar variation. Two additional bits of info (just to confuse you a little more ;-) ): 1) You can be growing two similar plants near each other, but if they flower at different times, they won't (can't) cross-pollinate. Corn is a good example: there are early, mid-season and late varieties of corn. Corn cross-pollinates easily because it's wind-borne, but if they tassle (the 'flower') at different times and there is no other corn around (esp upwind), they won't cross. If Alfie's apples (above) needed a pollinator variety, and he accidentally planted a variety that bloomed a month after his Macintosh, he wouldn't get any apples. 2) OP varieties can be 'manipulated' even within the variety. You can have a packet of seed of a single variety of an OP plant, and each seed inside will have a tiny difference about it. Many people will grow a particular variety that they like, and they will watch for 'special' ones among that variety: a tiny bit earlier, a slightly larger fruit, a sweeter flavor, a slightly higher yield, etc, and they will mark it and let a few fruits of that plant mature and collect the seed. The next year, they plant that seed, and again look for 'special' plants. Every year, they keep doing this, and end up (hopefully) with localized variety within a named variety that is especially suited to their local conditions. It's still the same variety, it's still OP, it's just an improved variation within that variety. If you bought seeds from a grower in BC, and you bought the same variety from a grower in ON, the local seeds might produce plants that had a slight edge on local conditions, concerning earliness, adaptibility to hot summers, or ability to grow with a bit less water. The seeds from BC might adapt better to cooler summers, more humidity, and a longer season.

My Santa Rosa used to have loads of plums each year. After my sand plum died a couple of years ago my Santa Rosa has not produce over a dozen plums. I was told on this forum that it is self-fertile to a point but needed a cross pollinator to produce a full crop.

This article provided some decent info on the topic. Generally, I think the answer is 500 feet apart, unless isolation methods are adopted (bagging branches or entire plant). http://savingourseed.org/pdf/IsolationDistancesVer_1pt5.pdf Chris

And the larger question to me is for what purpose are you saving seed from some OP varieties. If for home use then you need not be so concerned but if trading seeds or SSE listing them, etc., then seed purity is more of a concern. I'm glad you were directed to the FAQ here on How To PRevent Cross POllination b'c there were several of us that spent a good deal of time on that and then it was approved by those who were here at GW at the time. And I'm not all that biased but I do thonk it's perhaps the best discussion of X pollination on the net, and with pictures to boot. Different insects that can pollinate can fly in excess of two miles, so there's that. My rows were 250 ft long, plants 3-4 ft apart within the rows and rows 5 ft apart and my cross pollination rate was about 5% meaning that of seed saved from 100 varieties that on average 5 of them would be cross pollinated. There are lots of variables that play into X pollination and there's an excellent article at SOuthern Exposure Seed Exchange written by Dr. Jeff McCormack who owned SASE before he sold it and he outlined in great detail all those variables. So while my experience where I grow my stuff says 5% there are places where it can be up to about 50%, but that would be rare. Carolyn