Keeper of the Forest — D.K. Holmberg

Eris Taeresin, third daughter to the king, is tired of being different. She's wasted months searching the massive palace garden for a flower that will let her join her sisters in lessons to learn the secret language of flowers. Each day the Mistress of Flowers finds some reason to refuse, all while her sisters found theirs easily, a fact they love to throw in her face. When she finally finds a strange flower that satisfies the stern Mistress of Flowers, Eris is told she needs to learn more about the flower before she can join the lessons, leaving her spending more days searching the garden. At least now she has Terran, a handsome young gardener, for company. Then, while her father's men fight a war in the north and with her oldest sister planning her wedding with the Saffra prince, Eris discovers the Mistress of Flowers might be more than she realized. After overhearing her father's magi advisor, she begins to suspect the Mistress of Flowers is a flower mage who intends to use the garden in a plot against the kingdom. Eris soon learns the threat against the kingdom is deeper than she suspected and now she might be the only one able to save it from destruction.