Too bad plants ultimately burn. Probably will happen when they try to protect their part on the throne when Daenerys finally appears in Westeros.
What do you think happened the last time Targaryens appeared? Tyrells greeted them with open arms. Highgarden was never attacked because the Tyrells knew exactly what to do and say at the exact right time.
It was Tyrells who laid siege to Storm's end, you know the one Stannis talked about... Yet somehow after the mad king was killed the Tyrells got away with almost zero consequence. TREMBLE at the power of intrigue and being the literal breadbasket of Westeros.
Tyrells are very likely to support Daenerys actually, specially right now since they are pissed at both Lannisters and Stannis. I can see many similarities between Dany and Renly, and the Tyrells were a Targ supporter before, and they supported Renly as well.
Gold and Iron mines get dry, fish migrate and people die. The evergreen lands of highgarden will grow always and forever. Growing strong.