All of these plants require bright, indirect light. They should be placed close to a sunny window and turned once a week to prevent them from leaning toward the light. In rooms with poor light, place your plants under incandescent or fluorescent lamps. Plants located too close to incandescent light may be damaged from heat.
Temperature should be kept cool for best results with the holiday plants. Ideal temperature is lower than found in the average room. Your plants should do well if day temperature is 65° to 75°F and 50° to 60°F at night.
It’s important to keep these plants evenly moist. Avoid letting them become bone-dry or water-logged, which could result in root injury.
Flowers will eventually fade on your holiday plants. Remove them when this happens. Removing faded flowers improves the plants’ appearance and prevents seed formation, providing more energy for growth.
Poinsettias will eventually drop their leaves. This is normal. The plant is going into a resting stage. As leaves begin to drop, reduce watering until you’re watering only enough to keep the roots and stems from drying excessively. In April, prune the stems to about 6 inches, begin watering, fertilize and place poinsettias where they’ll get plenty of light but not direct sun. Forcing poinsettias to re-flower for the Christmas season can be a challenge within the average home environment.
Christmas cactus, being a short-day plant like poinsettia and chrysanthemum, responds to the shorter days and cooler temperatures of fall in order to stimulate flower production.
The flower buds will form regardless of day length when nighttime temperatures are 50 to 55 F°. But when night temperatures are at 60 to 65 F°, the plant must be protected from any amount of artificial light at night from September to November. Flower buds seldom form at night temperatures above 70 F°. After flower buds are well developed, they will bloom at normal room temperature. Temperatures above 90 F° may cause flower buds to drop from the plant.
To assure lots of flowers, I have found it easiest to simply place the Christmas cactus outdoors during fall so it will be exposed to cooler temperatures. Outdoors, place the plant in a lightly shady area. Provide protection or temporarily bring the plant indoors during high winds or heavy rain. But most importantly, do not leave your plant outside when a frost or freeze is expected. I made that mistake once and lost a nice Christmas cactus as a result.