Capable of being made green or capable of becoming green.
From the verb green (to make green, or become green) plus the suffix -able (capable of being). A productive formation following English word-building rules.
While 'greenable' isn't a standard dictionary word, environmental scientists might use it to describe land that's 'greenable'—meaning it can be restored to vegetation after being barren!
Complete word intelligence in one call. Free tier — 50 lookups/day.