Plant's economy (6)
I believe the answer is:
thrift
I believe this clue is a double definition.
'plant's' is the first definition.
(type of plant)
'economy' is the second definition.
(economy can mean being thrifty)
(Other definitions for thrift that I've seen before include "Maritime growth" , "Care in using money" , "Extreme care in spending money" , "Being frugal" , "Economy - sea pink" .)