While I don't know the answer to your question directly, I do know that one makes lye from wood ash. Ergo, if you put wood ashes around your plants wouldn't that make lye when they are watered? I don't think lye would be good for plants.

For a potted pepper I would use a liquid supplement like Bloom Booster. Wood ash is high in potassium and works well in the field but it is difficult not to overdose in a container. Peppers also have a higher than normal magnesium requirement which wood ash does not provide. For that use a light dose of Epsom salt.

Pretty simply, wood ash is highly alkaline. If your soil is alkaline, it's not smart to use. My soil is alkaline, and I consider wood ash to be toxic waste. Agree that there are better ways to get potassium and magnesium.

My soil is acid and I use wood ash on my in ground veggie garden. In moderation! I think it's especially useful for new gardens in previously unworked or in land recently cleared. I would think that a small amount (teaspoon) of bone meal would be more useful, but I don't grow in pots so have no personal experience.

If growing indoors, I assume they are containerized plants. And if containerized, I would also assume you are providing them with proper fertilization as well. If so, there should be minimal need to add anything else.

"Bloom booster" fertilizers - those heavy on the P or K end of the formulation - are pretty much a gardening myth. Plants only consume what they need and as long as P and K levels are adequate, flowering and fruiting (seed production) will occur without need for additional supplementation of these nutrients. They do not take up these nutes in any higher concentrations during the flowering/fruiting stage than they do at any other time in their growth cycle. Generally, any fertilizer with a 3-1-2 formulation and a full range of macros will provide everything they need throughout the plant's life cycle

Are the plants flowering at all? If they are, are they being successfully pollinated so that the flowers are fertilized and will produce fruit?

I would look first to light conditions, heat and fertilization routine before ad-libbing with other inputs. And I would never add wood ash to any containerized plant, ever!!

Breaking a stem is said to increase flowering and thus fruiting. I tried it once this past season and was impressed with the production on that plant.

Thanks for all your replies about wood ash - sounds like something I should avoid, based on the consensus here.

John, what exactly is meant by breaking a stem? Any stem? How much are you supposed to break off? Can you give more detail?

To answer a few of the questions:

First of all let me say this is my first time trying to grow peppers indoors.

Yes, I am growing the plants in containers, under HLG 100 4000k lights. I know that 3000k are more ideal for the flowering/fruiting stage, but I was told the plants would still flower and fruit under 3000k, the harvest just might not be as abundant.

The temperatures are good during the day, and the lights produce extra warmth. Temps are probably a bit cooler at night than the peppers would prefer, getting down near 50 at times.

The plants are flowering, yes, - in fact they repeatedly put out a lot of flowers. I have been hand pollinating them with a qtip. however, generally the flowers simply drop off and don't produce fruit. If fruits do appear, their growth seems stunted. My serrano plant has two peppers right now, one which is medium sized, and one which is about half that. Those two fruits have shown no noticeable growth for a few weeks, and no new fruits have emerged.

I stopped fertilizing when the flowers appeared because I have read so many contradictory things about fertilizing peppers, with some people saying they never fertilize, and that the fruits will not be hot if the plant is fertilized.

Do you suggest fertilizing the plants through all stages of growth, and if so, how often? Would I be able to use the same Masterblend pepper/tomato formulation as I use for my hydroponics experiments to fertilize plants growing in containers in soil?

Appreciate your suggestions!

Once any seedlings have reached the true leaf stage, ALL plants grown in a container will need consistent fertilization, simply because grower supplied nutrients are the only ones they receive or have access to. Most commercial potting soils are nutritionally void.

I don't have the space so never tried to grow them indoors but outside, any of my containerized veggies will receive a dilute water soluble fertilizer application on a weekly basis. I prefer a Dyna Gro product as it has the 3-1-2 formulation all plants benefit most from plus a full range of micros, but anything similar would work equally as well.

John, you say "breaking a stem is said to increase flowering". Who says that? I can't find any such reports. There are good reasons for proper pruning of pepper plants, including strengthening stems and disease mitigation, but increasing flowering isn't among them, as far as I can tell. In fact, there are reputable sources that say that, in their experience, pruning does not increase yield.

dan - I believe it was on the Veggie thread, on here, a year or two ago. I've never had good luck growing peppers. This plant was a sweet Lipstick pepper. I tried it on one plant. It worked, I got more peppers off that plant than I got from all the plants I grew over a number of years! Is it possible that if you get good yields "pruning does not increase yield". Pruning is known to increase yields on many plants. However I never received a grant to study that.

I would say that if you aren't getting good flowering or fruiting or if. like me, you never get good production that you have nothing to lose.

John - I do believe topping young (6 weeks old or so) pepper seedlings does result in the plant bushing out more and an increased yield. I didn't notice much difference in large podded varieties like bells and banana but it does seem to make a big difference in production with smaller podded peppers like Jalapenos, Cayenne, etc.

Well, OK, but ...

https://www.sandiaseed.com/blogs/news/how-to-prune-pepper-plants-for-maximum-yield

"There are many theories on how to prune peppers for the highest yield. We've tried multiple ways of pruning such as topping pepper plants, but we haven't found that topped plants have necessarily produced more peppers than their un-topped counterparts. We've tried it both ways for several years, and the plants, when planted in full sun, seemed to do equally well whether they were topped or not."

and

https://www.gardeningknowhow.com/edible/vegetables/pepper/pruning-bell-peppers.htm

"When it comes to bell peppers, pruning at the beginning of the season, before the plant has set fruit, is suppose to help increase yield. The theory goes that the increased air circulation and better access of sunlight to the deeper parts of the plant will help it to grow more peppers. In university studies, this kind of bell pepper pruning actually slightly decreased the number of fruits on the plant. So, the theory that doing this will increase the number of fruits is false."

That second reference might be consistent with LoneJack's observations.

Dan - On the bells it seemed to increase sun scald for me too. My observations were only from one season of topping one pepper of each variety I planted and leaving the second plant un-topped and comparing growth and production so take them with a grain of salt.

Another con is that you need to start the peppers a month or so earlier than normal and then top them about a month before transplanting out to give time for the new branches to sprout from the leaf axles. It does result in a shorter, bushier plant on the small podded peppers.

Some gardeners swear by topping peppers, but I usually get more production than I need from my normal growing methods so I never bothered to try it again.

"We've tried it both ways for several years, and the plants, when planted in full sun, seemed to do equally well whether they were topped or not."

My plants aren't in full sun. I have an acre and a half and there isn't a single spot that gets full sun. I find it odd that that statement is in there. So I'd say that they were implying that "In partial sun you'll get better yield by topping peppers". But that's my evaluation.

My pepper plant was a Lipstick sweet pepper I topped it after seeing only 3 peppers on the plant. One was at least 2 inches long so it was well after transplanting.

Sorry, but that doesn't make sense. They were just reporting that the plants weren't stressed by any obvious deficiency, like shade. It certainly doesn't mean that if they were in shade, or maybe total darkness, you'd get improved yield from pruning. But yes, the benefit of pruning may indeed depend on the variety of pepper.

As I read the statement they tested growing in partial sunlight and they did better when topped. I say this because if you're doing a study you don't make a statement unless you've tested it. There's a lot of ways to stress a plant and they didn't mention the others.

However from my limited studies, one plant, I'd be confident that if you can't grow good peppers you have nothing to lose; especially if you have multiple plants.

I believe the point that they made very clearly was that if you want full yield, you need full sun. That has nothing to do with pruning. I saw nothing in that article that said that they tested growing in partial sunlight.

The OP doesn't have full sun, the peppers are growing indoors. There's a question about a lack of minerals like phosphorous and potassium. Whether wood ash will help.

I found a solution to my problem. which has been confirmed. I offer it as a possible solution to the OP. I'm going to quit arguing the meaning of the disclaimer to the topping study.

Here are links to Utube videos on topping peppers.

First Link

2nd Link

I got these links from today's discussion of topping peppers on this months Veggie Tales thread here on Houzz. There are additional links to topping peppers on the "First Link" above.

Thanks. Those are interesting. What I see in them is that topping the peppers makes them bushier and strengthens the stem. Not completely obvious how that bears on productivity, though. Mine get plenty bushy without topping, and I always cage my peppers, since they grow 3-feet tall. I'll grant you that with respect to productivity, there appears to be some controversy about topping. I'd have to assume that if you have a short growing season, topping probably isn't smart. Mine is very long.

If the peppers are grown indoors, pollination may not be taking place because of lack of air movement and insect activity. Maybe a fan would help.