If sealed, self-sustaining terrariums need very little to no maintenance. Small and slow-growing foliage plants, miniature ferns and mosses are great for sealed terrariums, and succulents and cacti ...
‘Doctor Mules’ is a bright, vivid purple, the four-petalled spring flowers showing up well against pale stone, and the whole plant is neater and less straggly than the unnamed types so often seen.