The only way a plant would cross pollinate would be if you saved the seed, and planted it next year.okiegirl1 said:do different flavors of the same plant cross pollinate? (lemon basil, cinnamon basil, Italian basil, etc.)
If you want to save seed, the way around that is to only let one variety flower and produce seed. You would trim the flowers off those that you didn't want seed from. I'm pretty sure that if you bought plants from a retail source that they would be hybrids that wouldn't grow true to variety anyhow. If you get open pollinated seed like from Seedsavers then you would have to do the above. Isolating the flowers by distance doesn't always work because bees fly, wind blows pollen,etc. More info than you wanted, isn't it?