Gardening

Plant varieties are essentially inbred, so to get strong but still predictable plants, you need to cross two varieties that have some genetic distance.

The plants resulting from a cross are called F1. F1 seeds are comparatively expensive because of the effort required to make them. (Still, they are very cheap compared to other expenses.)

If the storebought peppers are F1 then their seeds are F2 and will be a random combination of parent traits instead of the perfectly predictable F1.

Another reason to buy seed is that you can grow much more interesting peppers. For instance beautiful purple striped Blot peppers or tasty Jimmy Nardellos.

Pepper seeds begin to mature when the pod turns color. Green peppers are immature peppers and the seeds are not viable. Red or yellow, the seeds may be viable.

The largest issue with using store bought fruit is the seeds need to be treated with TSP (Trisodium phosphate) when they are harvested. This treatment kills tobacco mosaic virus. TMV and other tobamovisues are common in production areas.

The plants will also be a segregating F2 plant. So the fruit/plant will look a little different from the parent (F1). Not a big deal in my opinion.

The reason supermarket pepper seeds may not fruit or be stunted/weird is because the fruit is almost always picked young before the seeds get to full viability. Pepper fruit needs to be almost wilting before the seeds will be mostly viableand more potent.