How to keep my stem plants from rotting?

[Runsoncoffee]

Just about any stem plant I buy eventually rots from the bottom up. I can not figure out what’s causing it or how to fix it.
I have sand as a substrate, and have tried to put the plants in small cups with gravel in it to give it more circulation. I’ve tried spacing the plants out so they all get plenty of light at the base. I’ve tried experimenting with the fertilizer. I’ve even tried floating them in my 5 gallon until they grow better roots, then putting them in the substrate to grow better root systems before I put them in my 75 gallon. I’ve even tried the liquid co2 in the 5 gallon.
Nothing seems to help.
Any advice would be great!

 

[Caliban07]

What minerals are you giving them?

 

[Runsoncoffee]

What minerals are you giving them?

I give them flourish fertilizer and phosphorus or potassium (forgot which one I have) weekly. And I have root tabs I give to everyone as needed

 

[Caliban07]

It sounds like you’re missing two of the three macro nutrients (the nutrients plants use the most)

Flourish doesn’t contain Nitrogen or Phosphorus. So if you are dosing phosphorus you are missing nitrogen but if you are dosing potassium you are missing both nitrogen and phosphorus. Most common root tabs will only provide the micronutrients too unless you make your own using osmocote.

Make sure the light isn’t too intense too as the more powerful the light the more likely it is you will need to use co2.

 

[ColdKoi]

I agree possible nutrient deficiency, or maybe just ‘new plant syndrome’

I had a similar scenario with my ludwigia when I first tried planted tanks. Once the plant started to mature, the stem would get pretty bad looking. I’d clip it off and re-plant the top, the original stem would hang onto life for a little while but eventually it completely rotted off (trimmed it and re-planted and it was good)

Maybe something about the water parameter change or whatever but once the original plants did the exact same thing, all of the replanted clippings have been awesome. I originally bought 2 bunches of them and now I’ve got them polluting my 36 and 75gal tanks, I’ve had to start tossing out the clippings lol