How to plant moneywort?

[fishshl]

I bought moneywort around one month ago and plant them into gravel.
But now it looks rotted not only the stem under and just above gravel,
also the leaves. Did I use the right way to plant them?

I have 65W cp 50/50 on my 20G H tank.

Any idea? Thanks in advance.

 

[Jchillin]

You planted correctly. Did the moneywort have healthy roots or was it a cutting that needed to root? Also, what are your tanks parameters (NO3, K, ph)? Are there any other plants in the tank?

 

[fishshl]

It's a cutting. Does it mean I only can plant root into gravel exclude stem?
I need test NO3 and ph. I think NO3 should be above 20 and ph above 8.