i keep posting this, there is a difference between plants surviving, and plants thriving, plants have evolved over millions of years to adpat to climates. True they can survive seasonal fluctuations in water quality and temperature, whereas fish migrate. However! if you provide them with the optimum you will find your plants will respond more positively. It has been widely accepted that in planted discus tanks it is easier to introduce discus to lower temperatures than find plants tolerable to high temperatures. Most planted tanks are kept at 26degC, even hekel discus can be kept at this temp.