1.5 meter rootbound bamboo with rust colored roots

[Alaska]

Hello,

For over 1 year 3 very tall lucky bamboo stalks have grown happily in Anchorage, out of direct sunlight in a vase with maybe 8 cm of water. Just lately, it is still green but it looks like the leaves are sagging, not perky.

At closer inspection, the roots are very matted and rootbound in the container and have turned rust or orange colored and the water was very murky. We replaced the water and washed the vase, but did not know what else to do. Do we need to trim roots? Plant in soil?

Thanks for any advice!