Place your calla lily plant in an area with partial shade during the warmer months. A patio or shaded spot works well.
Keep your calla lily in a pot with adequate drainage and an overflow dish, otherwise the plant may develop root rot.
Water your mini calla lily regularly. The soil should stay moist to the touch, but not wet or soggy. Don't let the soil dry out completely.
Give your lily fertilizer or compost every two to three weeks while it's growing and blooming. Apply fertilizers per manufacturer instructions at the lowest concentration possible to avoid burning the plant.
Renew the lily tubers every winter. Remove brown and dead leaves and blossoms after the blooming season. Remove the tubers from their potting soil, and place them in a paper bag or box with slightly damp perlite, vermiculite or peat. Keep them in an area with temperatures between 45 and 50 degrees Fahrenheit. Keep the tubers here for two to 10 months, depending on the growing season in your climate.
Re-plant your tubers after the last frost in new soil mix. If you live in zones 7 to 10, calla lily does well outdoors year-round without bringing tubers indoors.