Posted: 03/09/2013 at 09:30
Stacey, if you've got insects around, and plants in close proximity, the odds of cross-pollination are high. The same applies to chillies and toms.
The only way to guarantee purity of heirloom (pure) seed is to "bag" the flowers prior to them opening. Same procedure with both chillies and toms.
You can make your own bags out of tulle or fine curtain netting with a sewn-in drawstring. My wife used to for me. These days I just cut the foot ends out of those short stocking things and use them. Just make sure the stocking is as light a colour as possible.
When a flower appears, but before it opens, slip the bag over the flower and tie it securely but not too tightly. Let the flower open first and it's vulnerable to insects. Here's a bag in place on a Cherokee Purple tomato plant that I'm using for saving seeds. In this case, I've bagged a cluster of flowers:
Just keep checking inside the bag to see whether fruit has set. As soon as the fruit has set you can remove the bag. There's no more possibility of cross-pollination. If fruit doesn't set for whatever reason, move the bag on to another flower. But don't move the bag between varieties for obvious reasons.
Make sure you identify the fruit that you know is pure. As the plant grows, the pure fruit will change position and it's too easy to forget which one you bagged. I tie something next to the pure fruit to identify it as pure.
One thing. Hotter varieties of chillies don't need any different treatment to mild or even sweet varieties. The heat is in the variety's genes.