[malANDmatt]

How do I trim this or do I need to? Recently got a bunch and it's already taking off. About how tall will it get? Thank you all.

 

[discuspaul]

It'll grow quite tall - up to the water surface depending on tank height.
Hygros can generally be trimmed quite easily - you can keep them in pretty much whatever shape & height you wish - just trim away anywhere around the top growth.

 

[malANDmatt]

Ok. Thanks. I would actually prefer them in the background or midgrround of my tank so I'll let them grow taller.