How to judge root health from leaf growth

1. Old leaves have burnt tips, and new seedlings get burnt tips before they have even matured;

2. The leaf sheaths of new seedlings turn black and wither too early;

3. Growth stops, with no new shoots emerging;

In such cases, you should repot the plant and inspect the roots.

(Personal humble opinion, for reference only) http://www.dfac.cc/showtopic-18-210215-0-0-1.htm