A water-grown plant needs suitable roots and a carefully managed transition to potting mix. Check its identity before assuming every cutting responds the same way.
Check the plant before changing its growing method
A water-rooted cutting and an established plant in a hydroponic system are not the same situation. Confirm the plant's identity and inspect its roots before choosing a potting method. Remove decaying material from consideration rather than expecting a new medium to cure it.
Prepare the container
Choose a suitably sized pot with drainage and a growing mix intended for the plant. Handle the roots carefully and leave the plant stable in the new container. Check moisture as the mix settles rather than keeping it permanently saturated to imitate the old water environment.
Watch new growth
Keep the position steady while assessing the transition. Stronger sun, a new pot and extra fertilizer all at once make problems harder to interpret. Monitor the roots' conditions and new shoots, using plant-specific guidance if the transition stalls.
Related reading: Water-Grown Houseplants: Containers, Roots and Maintenance.