Peppers can self-pollinate, so it is possible to save viable seed from just one plant. However, peppers can also cross-pollinate with other pepper varieties, especially when there are plenty of pollinating insects around. If you are trying to keep a variety genetically pure, the more varieties you grow, the more important isolation becomes. Depending on insect activity, you may need as much as 1,600 feet between varieties to reliably prevent crossing! We’ve gotten away with much closer spacing on our farm because we grow lots of other flowering plants between our peppers, giving pollinators plenty of other options.
For long-term seed saving, it’s best to save seed from 50 or more plants, or as many as you reasonably can. Saving from just a handful of plants may work for a season or two, but over time we’ve noticed that small populations can lead to deterioration of the variety as genetic diversity is lost.
When saving pepper seed, be sure the fruit has reached full maturity and its final color before harvesting. Letting peppers become slightly overripe on the plant can give the seeds even more time to mature. Scoop out the seeds and allow them to dry completely before storing.
A note about hot peppers: Wear gloves when handling hot peppers, especially when removing the seeds! One method we like is to cut the top off the pepper with the seeds still attached and let the whole seed-filled portion dry. This gives the seeds a little extra time to finish maturing before they are separated and stored.