A Christmas cactus that blooms on time
It flowers when the nights get long and cool. Give it six weeks of darkness from October and it will bloom for the holidays.
The Christmas cactus is a forest plant, not a desert one, and it keeps a calendar. It blooms when nights are long and cool. In a warm flat with the lamps on until midnight, it can miss the signal completely and flower in February, or not at all.
The six-week trick
From early October, give it at least 12–14 hours of real darkness every night for about six weeks. A spare room with the lights off works. So does a cardboard box over it in the evening, if you remember to take it off in the morning.1 Water a little less in this period.
When the buds appear
Small pink tips at the ends of the stems mean it worked. Now leave it alone. Moving the pot, turning it towards the light or a sudden draught can make it drop every bud overnight.
- Keep watering evenly while in bud and flower.
- Do not repot while it is flowering.
- Pick off faded flowers to keep it tidy.
After Christmas
Once it finishes, it rests for a month or two. In spring, repot if it needs it, feed it through summer, and let it spend the warm months in a shady spot on the balcony. Then in October, the darkness starts again.
A Christmas cactus can live for decades. The one in our studio window belonged to Olena's grandmother, and it has never once bloomed on Christmas Day. It prefers St Nicholas.
Notes
- Temperature helps too: at 10–15 °C at night the plant sets buds even without perfect darkness. A cool windowsill in a north room often does the job on its own. Jump to footnote reference 1
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