Lately I noticed my peppers are turning red when they are still tiny size. The peppers were normal size 2-3 months ago but recently a lot of the peppers are red when they are still very tiny. There's a few peppers that are still normal size but 90% are tiny size.

Do you know why? Is it time for me to trim my pepper plants down? They are 4-5 feet tall right now in containers and I just planted them last year.

Thanks

Any way to plant in ground?
I had a plant produce a tiny pepper over the winter, after I dug it out of the ground and potted it up for the winter...
I suspect it had more to do with lack of nutrients than any thing else.
Trimming the plant wouldn't be my first choice if I wanted peppers.
The larger the plant, the more peppers it's able to set... in my experience.
If no room in the garden... Maybe repot up to larger container?

I've seen small peppers turn red due to insect damage or rot- maybe it is a stress reaction of some kind?

I would check moisture levels and nutrients in your pots. Have they gotten rootbound?

I think it's root bound. I might move it to ground.

Another question about trimming. Should I trim pepper plants or just let it be? If so when to do it and how low can I trim it down? It's 4-5 feet now.

It's growing season now.
Do you want fruit?

As I posted above... avoid trimming!

I dig and containerize in the Autumn, and while it sux, will trim enough to get plant through door... your plant isn't coming back inside, no need to cut back.

In the Spring, I might cut any dead branches off... but I certainly wouldn't remove live tissue...

I have no fruits now. I think because it's been producing fruits throughout fall and winter.

Peppers rest awhile, then, with water, nutrients, maybe a bit of fresh soul, they will set fruits again, while peppers can grow 3 to 8 years, it all depends on the conditions. No trimming now, no, no, no. Trimming is done in cool weather on trees and such, but your pepper if you were going to prune it, should have been done when it was maybe 18" tall. NOW? Just give it the care and feeding it so richly deserves and get ready to see another flush in a few weeks.

Can I move my 5 Thai chilly peppers from containers to the ground now? I'm in zone 10.

Yes, definitely. I suspect you could leave them outside year round in your zone.