My issue is that I cannot find a way for good watering, and I get lots of root rot.

I live in Germany, and I use the compost from the local market for my indoor plants.
for 6 months, the sun does not hit my Wintergarten, but the temperature is around 22, normal humidity, and have grow lights there.
But I get lots of root rot situations.
My explanation is, the compost soil holds water for long time, and does not dry evenly.
I think the plant sucks the water from around the roots, leaving the areas not covered by the roots wet.
So the plant get thirsty and needs watering, even though other parts of the soil is still moist.
Adding water to the thirsty plant, revives it, but ads more water to the non dried areas.
And because compost has lots of organic material, it starts growing bacteria and fungus, causing rot to spread in the whole pot.

And waiting for the whole soil to get dry, causes the plant to be thirsty and dies of low watering

Watering less causing plants to die from thirst, watering more causes root rot, I don't feel there is a good balance here, and it should not be so sensitive, it is not rocket science.

I noticed the issue when repotting dying plants, the upper part of the soil would be sahara dry, while the lower part is still wet.
I never noticed this happening when I was planting in the middle east area, and it is not caused by dry weather or sun or dryness, as sometimes it is close to sea side with high humidity and indoor planting.
Back there when reporting, the soil in the pot gets all dry, it does not retain water for long time, so not really getting root rot.

I tried many solutions:
- Used clay pots to help drying the soil
- Used mixture of normal compost with cactus soil, to make it more airy.
- I try get specialized compost from plant stores.
- I use my finger to know when the soil is dry
- I use the analogue soil moisture meter with the long metal stick.
- i have digital soil moisture meter, but it only measures the top few centimeters, same as with finger test.
- I use wooden sticks to check the deep parts of the pot if it is moist.
- I always make lots of holes in the bottom of the pot for better air circulation.
- Using smaller pots for plants.
- Made my own compost mixture, with perlite, humus, and other different material.

My next try is to try and get normal planting soil, with no organic or anything added to it, as I can easily add the needed liquid and slow releasing fertilizer and iron manually.

Please help with suggestion, and encourage me if you are facing same issue.

You are watering too much and the compost sounds like it is causing uneven drying times.
Forget moisture meters, they are very inaccurate!
I would use potting soil. Something blended in a bag.
If the top part of a pot is dry like the dessert and the bottom is too wet, it sounds like you have a drainage problem. You need more holes in the bottom of the pot to allow the water to escape. It sounds like in your case that the water is staying in the pot.

Plants do not recover quickly from root rot, especially if they are in the same soil that caused the rot in the first place. And if you keep changing pots, this pot, that pot, that is not going to help. It could take several weeks to grow a good root system. Maybe months. If the roots have rotted 100%, they may never recover.

I think you need to simplify things. Cut back on watering. Give them consistent bright light. And make sure water drains from the pot and they do not sit in water.

Sorry to hear the troubles, as you seem to have done your research and tried a lot of reasonable fixes.
Can you post a few pictures of plants and the area? Maybe someone will notice something else.

Hi & welcome! I also think we need more info & pics. This kind of theoretical discussion can be interesting, but may or may not be relevant to your specific plants, soil, and pots.

Sounds like you are really working to solve this. It would be helpful to know what plants you have, or could you post photos?

Here is a link to some extensive information about soil and watering for container plants. I found it very helpful, maybe it would be useful for you too.
https://containergardeningwith...

I agree, pictures and knowing what plants you're growing will be very helpful.

It would also be helpful to know what ingredients are in your potting mixes. I know that peat is banned in some parts of Europe, so your blends are likely different than ours. In the UK what we call bagged potting soil they call compost — same with you?

It is clear you've tried many solutions. I suspect you're on the right track but perhaps expect results too fast. I had started writing about soil drainage and then looked at Ms Doe's link. The man who wrote that definitely knows his subject and has written extensively in this forum. It's worth understanding what he's talking about. Unfortunately he is so excessively and needlessly wordy that his message gets lost in his tsunami of words. Stick with it if you can. And re-read the parts on drainage and soil types.

Looking forward to seeing your photos.

Drainage is always a big problem. The water should quickly drain through the soil just leaving it moist but not soggy. You might need more perlite.

Thank you all, and excuse wrong terms I may use, as I am not native English speaker. I started reading with the link, so far he confirms my doubts, I will continue reading to figure out some different solutions than what I did so far.

I will post some pictures tomorrow.

A question to all of you, so I can have a comparison.
Say in winter time, with central heating on, normal human suitable humidity, inside, non direct sun, 12 hours grow light, how often do you water medium plant size, in medium sized pot?
It seems if I water once a week, I get root rot, and I hear people water twice a week.

The top surface keep being moist for 10 days, and using wooden stick, shows moist button after 2 - 3 weeks, but plants seem thirsty at that point.

I know already I need better drained soil, which I am already trying with that.
I do have well drained pots with lots of holes.

Another thing, wouldn't too much perlite harm the plant? I am in a point mixing half compost half cactus soil.

There is no single set watering schedule. Too many variables. We ESPECIALLY need to know what kinds of plants you're growing.

Can't advise re lights, but in my mind, there's rarely any such thing as too much perlite.

I use half cactus soil half perlite for some plants. Again, depends on the plant. Photos!

The moisture below the roots is a problem. The pot should only be one inch (2.5cm) larger all the way around then the rootball.

But a major potential problem is how the pot drains. The bottom of the pot is a natural barrier to draining and drying properly. Adding anything else to the bottom (stones or pot shards) raises this wet area upwards into the root zone. Using pots with lots and lots of holes and just a piece of paper (paper towels or newspaper) or screen (window screen or craft screen) at the bottom will help fix this problem. It can't be entirely fixed because there will always be a pot bottom.

If the compost you are using is too water retentive, add perlite. Add enough to make the soil light and airy (1/3 to 1/2). Or use straight cactus soil. The amount of perlite you add doesn't really affect the growth of the plant because in the closed environment of a pot, you are in charge of water and nutrients.

Instead of perlite, I have also used pumice, pea gravel (granite gravel the size of a large pea), and crushed granite poultry grit. Any of these can be generously mixed in, and do improve drainage. Depending on the plant, I've mixed soil with anywhere from 20% to 80% grit. The plants like this much better than soggy muck. Roots need air!
I've also used "un-watering" wicks, they help some.

⬆️⬆️⬆️I think Ms Doe and I are on the same page. I also prefer pumice and use "reverse wicks", but only for my outside pots.

Agree with Lucy too. Once you get it right, life will be incredibly easier.

I referenced perlite because that's what khaeid mentioned. I too prefer Pumice but I suspect its not as easy to come by if you aren't in the western US.

Wow, you have a wonderful variety of plants!
I don't think you will find one watering schedule that works for all of them. I water Dracaena and succulents once a month in the winter, others once a week. But that is in my house in Arizona, quite different conditions. Everything is watered thoroughly, until some water runs out into the saucer. In the summer, some go onto an outdoor porch and get watered twice a week.
Another trick I have used is to buy gritty bonsai soil mix, with a small amount of bagged soil mixed in. This will drain fast and not retain water. Some plants will require more frequent watering and low dose complete fertilizer.
Improving your potting mix will help.

What a beautiful collection of plants! I don't see any signs of root troubles and think you should keep doing what you have been doing. Your expressed concern about "overwatering" means you're not doing that, so as long as plants don't get too dry, everything should be fine.

I'm gobsmacked at your collection. I can't be the only person in this thread who expected to see a few unhealthy plants. Lol!

I don't see evidence of disease or failing plants. A few of your pots might be a bit large, but not drastically. Maybe those halo lights would be more efficient if set lower, and I wonder if a small fan in some of those crowded corners might improve air circulation — but those are all minor tweaks and shouldn't be causing widespread root rot. I'm curious, can you show us a specific plant you believe is suffering root rot?