My christmas cacti are coming into bloom . How much watering should they get now ? Why do the blooms fall off when they are only halfway developed ? Other tips please for growing them ?
It is great to hear your Christmas cacti (Schlumbergera x buckleyi) are coming into bloom, some welcome colour in the house in November. Christmas cacti are forest cacti or epiphytes and are native to woodlands and jungles rather than the arid regions that desert types call home, so the secret to success is to counter these “desert” like conditions.
With regard to watering during spring and summer, keep the compost moist without allowing water to sit in the saucer. During winter, leading up to and during flowering, allow the surface of the compost time to begin to dry out between waterings. However, once plants have flowered keep them just a bit drier until spring arrives and growth becomes active again. Use rain water if your tap water is very hard.
Other tips (which will hopefully help you to retain those blooms) include being careful with the temperature and humidity your Christmas cacti experience. Christmas cacti requires as much bright light daily as possible but as a forest type cacti they should be shaded from direct sunlight ( bit of direct light is acceptable), try an east facing windowsill. Too much bright light will cause yellowing and ill health. Forest type cacti require higher humidity so mist frequently. Forest type cactus prefer 55 degrees to 70 degrees F, 10 degrees to 12 degrees C but can tolerate temperatures down to 40F (5C) during their rest period.
Feeding: high-potash liquid feed fortnightly from March until the flower buds have formed.
Repot the Christmas cacti when young (use cacti compost), but later repot only when necessary because a small pot will encourage flowering.
There are a number of different hybrids that flower at all sorts of different times through winter and early spring. They are “short day” plants (the shorter days of winter tell them to start initiating flower buds) and sometimes refuse to flower if they are exposed to too much artificial light. Once buds are formed, avoid moving the plants as in turning back toward the light the bud might drop off. Cuttings consisting of two to three segments are easy to root in spring. Providing you remember to water them a spell in the garden during summer will often help them to flower well the following winter. To get these plants to reflower, you need to give them two rest periods – one for 6-8 weeks after flowering and the second from mid September to mid November when flower buds form. The plants should be kept in a shady spot in a room with a temp between 10 and 14 degrees C and watered infrequently between these two periods (i.e in the summer) the plant should be kept in a shady spot outdoors.
In summary, some tips to counter flower drop: look out for dry air, too little light, avoid moving the pot and possibly too much heat. Get into a routine for those rest periods and enjoy those blooms!