What’s the reason why the leaves turn brown gradually from the relatively lower leaves? For the plant in first 2 pics (the zebra plant)I have avoided the AC or wind; watered when it’s almost dry ( almost dropping a little bit and then I watered) given it indirect sun lights like 3 hrs per day…..What is the problem and how can I stop it? It happened to my another plant as well. See the third pic. I tried to water when it’s completely dry but leaves’ edge turn brown and dry out especially after I water it gradually….