Position black rose plants near a south- or west-facing window where they will receive bright sunlight for at least eight hours each day, which is required to maintain the characteristic blackish-purple color of the foliage. Avoid keeping black rose plants in shade, since they will take on a greenish or reddish color.
Maintain temperatures around the black rose plant at about 70 degrees F at all times. Protect the plant from cold drafts and excessively humid conditions, since both will stress the plant, which will cause it to drop its leaves.
Water black rose plants regularly during the summer months. Moisten the soil to a depth of 3 inches. Allow the soil to dry out before watering again. Decrease water in winter. Apply only enough water to keep the leaves plump during the winter months.
Feed black rose plants once a year, around mid-May. Apply 10-10-10 ratio fertilizer to the soil according to the instructions on the label. Water the black rose plant thoroughly after feeding it.
Prune off and discard the black rose stalks after they flower and die back. Cut the stalk off at the base, using pruning shears. Cut the stalk off flush with the surface of the soil.
Watch for signs of mealy bug infestations -- white, cottony masses beneath the leaves or clear, sticky liquid on the stalks. Treat suspected mealy bug infestations with a cotton ball soaked in rubbing alcohol. Rub all parts of the plant with the cotton ball. Apply the alcohol once a week for three weeks to prevent further infestations.