Undoubtedly, judging by the situation at the time, it was evident that the plants had a fear of death. Zhou Tian utilized the threat of flames to reach that point. Otherwise, in a normal situation, if Zhou Tian were to fight those plants, he would find it difficult to defeat any one of their members.
At present, Zhou Tian finally managed to reach that point using flames, but a sudden flying leaf warned him that although the plants fear fire, it would still be impossible to subdue them with just a little flame.
After all, regardless of their fear of fire, the plants' strength was undeniable, and they wouldn't give up hunting Zhou Tian because of some flames. Thus, even if Zhou Tian continued to use those tactics, it was unlikely his actions would have any good effect.