Problems with Leaves Turning Red on a Christmas Cactus

Excessive Light

• When a Christmas cactus is exposed to excessive light, the leaf segments will begin to turn red or purple and may become limp. These plants prefer a sunny spot indoors or a shaded or partially-shaded location outdoors. Balancing the amount of light the Christmas cactus receives is important if you want blooms. The plant requires at least eight days with each 24-hour period consisting of eight hours of sunlight and 16 consecutive hours of total darkness.

Moisture

• Regular watering helps the Christmas cactus to maintain good color and prevent wilting. Constant moisture around plant roots will also negatively impact the plant and excellent soil drainage is crucial. As a general rule, when soil an inch below the surface feels dry, water the plant deeply with water warmed to room temperature. Christmas cactus also benefits from sufficient humidity and might suffer discoloration or languish in the dry conditions common in many homes during the winter. Setting the potted plant atop pebbles in a water-filled tray can help to raise the humidity around the Christmas cactus.

Nutrients

• Leaves turning red on a Christmas cactus could indicate a nutrient deficiency such as inadequate phosphorous. Fertilizing the plant with a slow-release or diluted liquid fertilizer with a 3-1-2 or similar formula will quickly correct the discoloration if insufficient nutrients alone were responsible. To encourage blooming around the winter holidays, do not apply any fertilizer after about early September to avoid interfering with flowering.

Other Considerations

• After every two to three years of healthy, vigorous growth, a Christmas cactus can become pot-bound. When roots are very crowded in the container, the plant is often unable to take up sufficient nutrients and will require very frequent watering. If this is the case, the Christmas cactus will benefit if it is repotted into a slightly larger container with a high-quality, well-drained soil or even a soil-less growing medium.