Depends on the cultivar, The older cultivars were bred for green bells, which holding green was a virtue. Many of the newer hybrids were developed for the ripe bell market and turn red much faster. Two to four weeks is about the average. It is more difficult to get unblemished ripe bells, lots of things happen to them on the way, which is why they are more expensive.

I wish I could answer your question, but I am struggling to grow peppers myself. I bought a chocolate bell pepper plant in May just before Mother's Day, and it looks the same as the day I bought it. I figured the first location I put it in didn't have enough sun. So I moved it to a really sunny location, and still saw no results. I am frustrated by the whole situation because it was the only plant my husband specifically picked out. He really doesn't care for gardening much ao I was happy when he gave his input on a vegetable he would like. Now I can't even get the stupid plant to grow.

Today in yet another effort to rectify the situation, I moved the plant to soil with more clay in it. I read on the Internet that pepper plants like lots of sun and sandy or clay based soil. I don't know if it is true or not, but since I have tried everything else, I figured it wouldn't hurt. I also bought two other types of pepper plants that were much further along. Maybe my husband will get his peppers yet.

Keep trying and good luck with your pepper plants.

They they a bad spot before turning completely red? Could be pepper maggots. An adult fly poke a hole in the pepper while it is green and deposits an egg. The egg hatches into a maggot. Peppers with this maggot usually start to turn red but they rot inside and sometimes at the spot of egg injection.
Sweet peppers (such as bells) are usually the targets.
To detect the maggots shake the pepper and the maggot will rattle around.

Jon

I read once to spray some epson salt(magnesium) and water on the blooms. This will make the peppers "set". I have done this once and had way, way too many tobasco peppers to use in a lifetime.

I do the epsom salt/water solution at flowering as well. One tbsp to a gallon of water is what you want. It does indeed help the fruits set.

Does epson salt have the same effect on tomato plants?