55 Gallon Tank Why can't I get stem plants to root?

I typically grow low tech plants relatively well. I use Easy Green ferts, Easy Iron, and the Easy Root Tabs (because they're nutritious soil they won't wreck my tank if my cories dig them up). Ever since I added the root tabs, my Nymphaea Stellata, Crypts, and more recent Amazon Swords (my reasons for doing root tabs) have all greatly improved in health.
However, I just can't get stem plants to root in my substrate, root tabs or not. I have some moneywort and ludwigia natans that haven't grown any roots in the 3 weeks that I've had them. I kept them in their plant weights (not lead) so that my fish wouldn't interfere but I have no luck. I had this same issue previously with anacharis and rotala rotundafola. I have some hygrophila corymbosa that I think has rooted, but it already had roots when I got it. I have a bit of hygro pinnatifida that has some small roots it grew as well but I'm growing it as an epiphyte.
I just can't get cut stems to grow roots. I even tried floating to cause rooting and I got nothing. What is causing this/how do I remedy it (other than CO2 but I shouldn't need that for these plants).

 

What’s your lighting (and photoperiod) and substrate

 

What’s your lighting (and photoperiod) and substrate

8 hours using LED light. Regular gravel but I have dirt root tabs

 

try growing them in a small pot with the pot submerge in water and part of the leaves exposed to air. if they start to root in a week, the problem is CO2. if everything is right, the only thing missing is CO2. some plants might not need alot of CO2, but they still need them to grow. its the no.1 nutrient that plant needs.

 

try growing them in a small pot with the pot submerge in water and part of the leaves exposed to air. if they start to root in a week, the problem is CO2. if everything is right, the only thing missing is CO2. some plants might not need alot of CO2, but they still need them to grow. its the no.1 nutrient that plant needs.

The plants grow, just not the roots, if that makes a difference

 

recently the plants in my tank overgrown and i did some trimming and brought the trimmed plants to my mums tank.
if i replant the trimmed plants in my tank, in a week it would have grown taller significantly. i usually replant them in front...then when they are taller i move them to the back. and there are roots when i replant them to the back.
my mum side is a different story, the plant grows but no roots.

the main difference in the 2 tank-my has CO2, my mums dont. in her tank i have tried many plants, in the end ony about 4 types ( dunno their names though) rooted and grew well in a non CO2 environment. many plants that grew well in my tank just dies off slowly in her tank when i tried planting them.

 

I've found it easier to float stem plants until the roots start to grow. After that, i plant them where i want. It's unsightly for a bit but it keeps the tank clean and doesn't damage the fragile stems of most stem plants like ludwigia. I'd remove the lead, let them float until you see roots, then plant. It's how ive started all of my stem plants and never had an issue. This might not work for you but I've heard other have success with this same method.

 

The biggest mistake people make with these plants is planting them as a bunch. Each stem should be planted separately. Trim off the leaves from the first 3 to 5 nodes then plant.

LED light? Is it a plant light?

Use root tabs as well as water column ferts. I use the Seachem line with Finnex lights to get these results.

 

The biggest mistake people make with these plants is planting them as a bunch. Each stem should be planted separately. Trim off the leaves from the first 3 to 5 nodes then plant.

Agree to disagree i suppose lol

I’ve pretty much always planted as bunches and been fine in low tech and high tech conditions with a variety of stems

 

i used to plant them as a bunch. initially yhey look ok. but once they start to grow. it becomes unsightly as large bushes branch out from a small base. now i plant them individually. not only do they look better as they branch out, there is also more space created between the plants that the fish ans shrimps can hide and rest upon. i have at least 120 shrimps of different species of neo caridinas plus about 20 mosqito rasboras and dwarf corys and in a 45x20x25cm tank. with drift wood and a HOB filter. unlesss during feeding, the shrimps are all hidden and less than a handful are visible.