Root on what, guest? I think we need more information, please. I'm not sure what you're asking.

keep the compost barely damp, the plant will develop roots to seek for water. general rule bt it would be better if we knew which plant it was.

Roots require water and air to grow well.
Don't have the roots too wet or sitting in water (except willows) as this encourages root rot. Ensure the soil around the plant is not compacted.
What is the plant and where is it situated?