Monster Girl Plant Diary is a Manga/Manhwa/Manhua in english language, SUGGESTIVE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Who knew that even a stationary plant could be surprisingly capable?! Our protagonist is a saint—or was, until she was betrayed by one of her fellow saint apprentices as well as her fiancé, a hero. In her final moments, she recalls her previous life, when she was just a normal Japanese high school girl, but that doesn't help the fact that she's being eaten alive by a massive plant monster. And yet, by a stroke of luck, she doesn't die for good, but instead reincarnates as said plant monster. With the upper half of a human and the lower half of a plant, she must now spend her life as an Alraune. And so, she tries to live the peaceful life of a plant, photosynthesizing all day! Welcome to the diary of a plant girl who just wants some peace and quiet, but something always gets in her way!