Q: I was given a Christmas cactus last year as a gift and I want to repot it now. Also, how do I get it to come back into flower for the Christmas season? – S.F., Albuquerque
Personally, as long as the plant looks healthy and the only reason you want to repot now is to offer fresh potting soil, then I’m voting that you bring the cactus into bloom for this holiday season and then after a bit of a rest, repot in February next year.
Here’s the skinny on triggering a Christmas cactus to set its flowers. You’ll want to trigger your Christmas cactus through the whole month of November until December 1st.
First I want you to stretch the times between the waterings you usually offer, so the soil dries out a bit. Now I’m not suggesting you allow it to become White-Sands-desert dry, just back off on the frequencies of the watering. If you water every five days, stretch it to every 8 or 10 days.
Also, don’t offer quite as much water as you usually would, either. You want the plant to dry a bit, creating a certain amount of stress.
Now this next bit will require faithfulness, because it’s sort of a chore. If you can and have a good spot that is kept cooler than the rest of the house, yet it still gets daylight every day, move the plant there. Your aim is to keep the plant cooler than it is used to being. That’s another stressor the plant needs.
Now this is the most important stressor you’ll need to do, each and every evening at sunset, you need to put the cactus in the dark. If it’s been moved to that cool spot and that room isn’t lit each night then that’s perfect. But if the cooler spot it’s been moved to still gets light in the evening, then you need to cover the whole plant – pot and all – so it doesn’t get any light for at least 12 hours daily.
I’m lucky to have a space in a fairly unused room that offers both the coolness and once the sun sets, strict darkness. If I find I need to enter that space I use a flashlight so the “triggering process” isn’t jeopardized in the least. Being kept in the dark for twelve hours of each 24 hour period is paramount.
Now if you don’t have a perfect spot to move the plant, make the darkness come to it. Find a stout corrugated cardboard box that will fit over the plant without maiming it and set the box over the plant every night. This is the faithful part. Every night from now until the very beginning of December the plant gets covered, remembering to uncover the plant every morning. Cover at sunset, uncover each morning. Or keep the room dark every night and then fling open the curtains each morning.
Next, the first weekend of December, after the plant was moved to a cool, dark spot, or you’ve been faithfully covering and uncovering each night, stop. Move the plant back to its original spot or quit covering nightly. Offer it a bit more water when you do water, keeping it at the “less frequent” water schedule, still keeping it a tad on the dry side.
Within days, you should see wee little nubbins that don’t look like baby leaves start to show. They might look a bit like small, white knobs. Those are the flower buds starting to grow.
Within the following few weeks, the Christmas cactus should be ablaze with flowers all over the plant. It’s always a wonderment watching the flower elongate and then open, offering all that color.
I know the process works and once I received confirmation from a reader who, although didn’t move his cactus, did cover it nightly and was rewarded with blooms. It was kept on a glass top coffee table and was quite the conversation maker during the triggering process. I was so happy for him.
In February after all the blooming is finished, that’s when you should go ahead and repot. It will be one of the first reminders written in your new calendar for 2022 and you’ll have something to look forward to next year.
Trigger away now to get those cheerful blooms and then look forward to a good chore next year.
Happy Diggin’ In.
Tracey Fitzgibbon is a certified nurseryman. Send garden-related questions to Digging In, Albuquerque Journal, 7777 Jefferson NE, Albuquerque, NM 87109, or to email@example.com.