Ancho chiles are dried poblanos, so look for a poblano plant. It would be better to buy locally so you can see that you are getting a healthy plant. You should see plenty of choices at big box stores or nurseries.

Yes, a Poblano would be a good choice. You might also try Fresno Jalapeno and a hot banana. Sweet Heat would be very good ... if you can find it.

Also, I agree that buying a somewhat larger plant at this time of the year from a nursery - or BigBox - would be good.

@CA Kate z9 How large of a plant would you recommend? Something appropriate size for a two-gallon container? What should I expect to spend for something that large?

@CA Kate z9 Since I am new to vegetable gardening, what are the fertilizer requirements for peppers? I will use Osmocote in the pot to just provide a base layer of nutrition. How often do I need to supplement that with additional synthetic fertilizer? By default I have a 9-3-6 Foliage Pro solution from DynaGro. I could use a half-strength application on the plants maybe once every two weeks?

• I just got back from a "scouting missioin" looking for Sweet Heat Pepper, but no luck. Every year I like to try something new, and this year it will be Lunchbox Red Pepper - "a sweet, snacking pepper." I thought it might be better for one person to cook with than the standard big bell pepper.
• Note that the Basil is in a 4" pot - $5.98 and the Pepper in a 6" - $9.98, but they are both only about 6" tall. I got these at Home Depot.
• I'll keep looking for the Sweet Heat, but doubt that I'll find it, unless it will be in some off-the-beaten-path nursery. Anyway, it gives me a reason to stop at every nursery I pass. 😃
• Oh, I forgot that you asked about fertilizer. I use one aimed at Tomatoes. They are all in the same family and, most likely, have much the same needs.
• I read that you should feed tomato food to any veggie that is now bearing fruit because they need the greater potassium. I don't know all the chemistry of it all, but I do know that this works.

What I don't know is why this post has bullets.

Two gallon pots are on the small side for a lot of peppers. While some root masses of smaller plants can be confined to two gallons with tending, the topsides are usually too big for it. A peppers taproot can tend to go deep, up to 3', but most of the time we plant and the taps don't go deep, so lateral roots develop. Those can fill space up to 12-18" deep. 12-18" plants can work in two gallon, much bigger than that and you start having topheavy and stability issues. And some soil mass and root confinement issues.

Poblanos get around 2' and are shrubby, many jalapenos can get to 3' with a 2' spread when grown well- both need more around a five gallon pot to be really happy plants. Fresno peppers can hit around 2' and can be grown in a two gallon with a lot of tending and some stabilization, you would do better to have them in a bigger pot. Hot banana peppers stay smaller and can be grown in a two gallon, but can still require stabilization to prevent tipping. Sweet heat is listed as smaller and can probably be grown in a two gallon- but likely would prefer a bit bigger pot.

How you want/need to fertilize depends on what your dirt is. There are mixes with feed in it, mixes without, straight components that people blend to make their own mixes. If your dirt is fed, that has an impact on what you need to feed it to feed your plants. Some folks like more synthetic chemicals, some like organic chemicals to feed with, that's a personal prefrence. But generally a tomato or veggie fertilizer works on peppers.

I recommend using tomato cages for pepper supports. Especially if you choose a pepper that has an open branching or heavy fruiting habit. A central stake or two can often be sufficent for a central branching or small/light fruiting habit if the pot is big enough for bottom stabilization.

@beesneeds Thank you very much for describing the root system of the plants I want to grow. That was very helpful! My grow bags are wide and shallow, so it sounds like that is the wrong container for this plant. It sounds like a 15-gallon container might be ideal and allows for the possibility of a tap root.

Since I make my own soil mixes and know a lot about the science of that, what I need is some guidance about what percentage of the soil should be organic. I guess these are not plants that want fast-draining soil. A typical commercial potting mix is about 60% to 80% organic. A typical commercial cactus mix is about 40% to 50% organic. Tapla's "gritty mix" is about 30% organic. I have experimented with tight control of organic content even down to 10%, for plants that easily root rot.

You can plant 2-3 peppers in a 15 gallon pot depending on the variety. Most of the more commonly found seasoning peppers can be comfortable at one each in 5 gallon pots. I have grown some rather large peppers that hit around 4' tall and bushy and then I did one in 15 gallon- the garden grown from that year got a bit bigger than the container one and hit almost 5'. Peppers don't have to have 3 foot depth for tap roots, just some peppers can form them that deep if happy and allowed to. The lateral roots with their 12-18" depth is more of a concern to accomodate in container growing. Also, a 15 gallon is great for growing one tomato plant- you can go patio or dwarf all the way up to some of the bigger indents if you got the support for the plant set up.

Can't really recommend your dirt. What works for me and my garden might not work for yours. I tend to use a combo of potting mix, homemade cold compost, sometimes toss in spent pots soil or some random other like if I got a couple bricks of cocoa lying around or if I'm turning out a ferment it might get mixed in. It's pretty high in organic content, not precise, and not tidy or clean mixes. I tend to make my fertilizers and teas, and that for sure isn't for everyone.