Listen, out the gate, I'm not talking about anything to do with plants. Whaddya wanna impale something with roots and drain the nutrients outta it, watching said roots grow into the shape of the victim? Wanna make any plant bear fruit? That's really cool, WHAT THE FUCK DOES THAT HAFTA DO WITH DIRT AND ROCKS. THAT'S COOL AS FUCK, WE ARE NOT AFFILIATED.

It's about manipulating what most people simultaneously take for granted and base their entire reality and civilization around. It's about being able to immediately create trenches, tilled fertile plots, ponds, rivers, lakes, cliffsides, canyons, citadels, even islands.

It's about ripping apart the works of deluded fools, tearing down bridges and walls, shattering statues, rendering battlefields literally unrecognizable.

It's about breathing life into stone, making homunculi of wet clay/mud and stone to fulfill whatever purpose you wish. It's about imbuing the land itself with a will, be it your own or one that's eternally loyal to you. So that even if your castles or temples are destroyed, they'll still rise in opposition to whoever thought they could own it. Having a named desert you can find on a map as a unit you can send into battle.

It's about bringing forth devastation few other traditional elemental magics can. Commiting Grand Magic as opposed to casting it. Earthquakes (and depending on location tsunamis), pyroclastic flows, sinkholes, meteors, destruction of the earth as you understand it.

On it's face it's a humble school of magic, but with enough oomph you'll shape the world around you, subject to your will. The hearts of the people are still outta your reach, and getting hopped up on your own shit will ensure they stay outta your reach.
Make a farm, pal. Throw some rocks maybe. Teach a mudman to love. All other paths lead to disaster. Do Not Master Geomancy.