>> and 150 feet would be a joke
Yup. The other number cited on that thread was "25 feet". The distances cited are meaningless unless they also say what their target is: less than 1% cross-pollination, or less than 0.001%.
For home crop use, probably 5% to 10% would be acceptable, and 3% would be fine.
I often wonder what level is average in hobby seed traders - 10%? 30%? 50%?
One guy who trades hot pepper seeds adds "not isolated". I'm guessing he has mixed rows or blocks of pots with 10-20 varieties check-by-jowl. But peppers also have perfect, mostly-self-Pollenizing flowers.
(I read somewhere that they call it "pollenizing" instead of pollinating when the pollen never gets outside the bloom, but just goes direct from anther to stigma.
http://www.amnh.org/learn/biod... )
I think about cross-pollination with wind and insect-pollinated plants, not self-pollenizing ones. But then I'm not a breeder or commercial vendor or conservator of rare heirlooms.
Once I tried to start many species of Salvia in the front yard, or the back yard, avoiding having two varieties of the same species in the same part of the yard. But almost the only ones that came up were several varieties of S. coccinea that were forced into the same bed due to lack of room. Oh, well! Then I had to move the bed that had the most variety and best isolation. Grumble.
When I want to save somewhat-pure petunia seeds, I plant those in pots and planters, then move them as far apart as possible and deadhead thoroughly for a while. Then let them go. But they cross a lot anyway.
