Light and Temperature:
The Christmas cactus (Schlumbergera species) grows best in light shade. Full sunlight is beneficial in midwinter, but bright sun during the summer months can make plants look pale and yellow. Ideal growth occurs at temperatures between 70 to 80 °F during its growing season from April to September. Do not let temperatures rise above 90 °F once the flower buds are set in the fall. Continuous warm temperatures can cause flower buds to drop. The secret of good flower bud production involves temperature and day length (photoperiod) control.
Flower initiation requirements:
For best flowering the plants need...
· Bright light
· Night temperatures between 55 and 65 °F
· Long nights - Thirteen hours or more of continuous darkness each day is required before flowering will occur. Long nights should be started about the middle of September and continued for three - four weeks.
Watering and Fertilizer:
Water the growing medium when it is dry to the touch. The Christmas cactus is tolerant of dry, slightly under-watered conditions. Do not let the soil become waterlogged, especially during the dark days of winter. Do not let the soil dry out either. Reduce watering from fall through spring. Fertilize plants monthly from the time new growth starts in late winter or early spring, and throughout the summer using a one-quarter strength soluble fertilizer. Reduce fertilizer during the fall and early winter.
The Christmas cactus flowers best when kept somewhat pot bound. Repotting is necessary only about once in three years. The potting media must be well drained with good aeration, because the Christmas cactus does not grow well in heavy, wet mixes. A good mix may contain one part potting soil, two parts peat moss or compost, and one part sharp sand or perlite.
The Christmas cacti occasionally drops unopened flower buds, which may be induced by an excessive number of buds or a sudden change in temperature, light or other environmental factors, such as drying out of the growing medium. Lack of flowering is often due to light interrupting the long night period (13 hours) that is required for flowering initiation to occur. Streetlights or indoor lighting can disrupt the required dark period.
General cultural information for the Easter cactus
Easter Cactus: (Rhipsalidopsis species)
They should to be treated the same as other holiday cacti but at different times of the year. The resting period for this group is from December through February when plants should be kept cool (50°-60°) and dry until the flower buds form. Once the buds form, the plants can be give more water, light and higher temperatures. The plants flower from March until May. As the plants age they will develop corking on the older growth. This is normal and you do not want to remove.