Flowers only take a day to grow, so you might give it a try. Just plop some potting soil and seeds in and then alter the colors as needed with the pumace and a day later you've got flowers. Also I don't know what Balmung's prices are on soil, but it may be cheaper to purchase chocobo food from the Vath beast tribe vendor (don't think you've unlocked it yet looking at your level, but someone in your fc might have?). They're 348 gil each and if you're using G3 shroud soil, unless it's about 2,790 gil for the soil, you'll get more selling (or just not buying) the soil and just directly buying the chocobo food. Plus you get the food instantly and you're not spending the time/garden space on it. :D
