I don't know if watering in itself would cause premature ripe fruits, but I think you should water less in any case. Peppers like their potting mix to drain really well, with lots of perlite and bark if possible. MG is still fine, but will retain water longer than a chunkier mix. This might turn your bell and poblano pepper around as well. I think thick flesh varieties are more prone to rot from over watering. Some of mine did that last year when they were overwatered while I was away for two weeks. Even some of my thin skin hots cracked from it!

How's weather been like since the fruits set? I've also had many Habanero-like pods ripen when barely dime-size, but now have a few new pods showing signs of normal growth. This might have been caused by somewhat cool and cloudy conditions for me. I suppose several plant stresses might cause premature ripe fruits.

I just pick them as soon as I see a change in colour. Just do this and your plant should start behaving normally eventually, especially if an environmental stress is removed. Almost all my peppers had been doing terrible (in various ways) until a week or two and I now see improvement in all of them. Just give it a bit of time, good luck!

I'm going to speculate that the plant is not a Jalapeno but some other variety - either mis-labeled or a random seed in the packet if you grew it from seed. There are several pepper varieties that normally look and change color that way. Have you tasted any of them?

Dave

Thanks for the tips. These are planted in fabric bags so I would think I am not actually overwatering since all excess water will drain out or evaporate easier at least.

I never considered it's not actually a Jalapeno. I guess that's possible. I have not tasted them yet.

So I will pick the red peppers and try them out and see if they are actually ripe (spicy) or tasteless. Thanks.

I've harvested 15 beautiful ripe green jalapeños so I'm sure of the variety. Now I have two tiny ones turning red. Size of small strawberry.

I have to assume we're talking stress. A pepper turns red when it is mature. The pepper is just telling you "I'm done, and I ain't gonna do any more!" The goal of a plant is to produce seeds, so if a plant is stressed it will have a hard time producing more seeds, and whatever seeds it's already produced are going to be matured and kicked out. That may be in an unusually small fruit.

Many reasons for possible stress. Perhaps overwatering or underwatering, overly intense heat (it takes a lot!), sunscald, and perhaps also nutrient deficiency.