I want to do a decorate-a-plant-pot-and-plant-something-in-it activity with my Rainbows, but I don't know what would be best to plant. I want something easy to care for and nice to look at, ideally something that could live indoors or out. I have a coleus plant that has lasted years despite my very untender care, so that could work, but I'd love to hear other suggestions. Are there any seed mixes that would be good?