Now's the Time to Give Them "The Treatment"
Question: Hi, Mike: I'm a long time fan—I love your show—and I'm looking for your advice on how to get an old poinsettia to turn red again for the holidays. I know you've discussed this in previous years. Would you please remind me when to put it in the dark and whatever else I have to do? I'm sorry that we who are losing our memories have to torture you with repetitive questions all the time! Thanks,
- ---Amy Laub; Visiting Angels Living Assistance Services; PA
Answer: No trouble at all, Amy—now what was that question again?
Any way, don't apologize— this is the PERFECT time to discuss what needs to be done to bring all three holiday plants—Christmas cactus, amaryllis and poinsettias—into bloom for the season. The basic advice is pretty much the same for all three; they need a period of time—beginning right about now—where they either get a dark treatment, a cold treatment, or both. The key is to act NOW. The big reason people's holiday plants don't bloom on time is that they aren't thinking about it when they have to, which is three months in advance—but YOU will be! Here's the specifics:
POINSETTIAS: Despite their winter time popularity, these tropical beauties hail from Mexico, and can't take any kind of a chill. Don't even think about leaving a poinsettia outside in cold weather! Now, if you have plants still alive from last year, start providing them with total darkness for 14 hours every night. And I mean TOTAL! No night lights, streetlights—nothin'! Put the plants in a closet or under a box around 6pm and bring them back into the light at 8am the next morning. During their period of darkness, they must be kept at a temperature between 60 and 70 degrees (F., of course). During the day, they should receive six to eight hours of BRIGHT sunlight and enjoy temperatures in the mid-70s. Feed and water as you would any actively growing houseplant.
After about 8 weeks of this nonsense,you should see that distinctive red color emerging on the top leaves (unless, of course, you have one of those new yellow, pink or white plants). And yes— those are leaves; the flowers are the little yellow things in the center. Continue covering the plant at night until the colors are nice and deep— then just enjoy!
To keep it going for NEXT year, prune the plant back to around eight inches in early Spring when the colors start to fade, put it in a sunny window, feed it lightly, and then put it outside around June. Feed and water it over summer, bring in back inside at the beginning of September, repot it and start all over again!
CHRISTMAS CACTUS: Three similar"holiday cacti" are called by this name, but only one is the real thing. If, like most people, the branches on your so-called Christmas cactus have pointy teeth, you actually have a Thanksgiving cactus, which prefers to bloom in November unless you intercede. The branches of the much rarer Christmas cactus have scalloped edges—no 'teeth'—and like to bloom from December thru March. The Easter cactus, which typically blooms in Spring but often flowers periodically throughout the year, has 'teeth' that are much more rounded than the Thanksgiving type.
No matter which type you have, NOW's the time to 'tell it' to produce its holiday flowers. You have two choices: Dark treatment or cold treatment. Whichever you choose, water your cactus lightly now, don't water at all in October, and resume light watering in November. Don't feed until you see new growth appear next Spring.
DARK: As with poinsettias, keep the plant in total darkness from around 6 in the evening to 8am the next morning; during the day, the plant should receive bright, normal light. After about six weeks, it should have nice big fat flower buds. Stop the darkness thing, keep it in bright light during the day with nighttime temps in the mid-sixties, and those buds should open in another six weeks or so, depending on the light, room temperature and whether you were nice to chipmunks this year.
COLD: Keep your cactus in a very cool place—55 degrees is ideal—for the next six weeks; this gets those big fat buds to form no matter how much light it gets. Just don't let the temp drop below 50 degrees or those buds could be damaged.
Either way: If those flowers are moving along too fast for your timing, move the plant to a spot that's a little cooler (around 60 degrees). If the big buds don't seem to want to open, make it a little warmer and give it more light. Prune the plant back a bit after the flowers fade; then root those prunings and make more cacti!
AMARYLLIS: Yes, you CAN get that giant bulb from last Christmas to bloom again—if you allowed the green leaves to linger on the plant after its last flowering; they're what fuels the growth of the next set of blooms. (If you cut them off right after the flowers faded last year, you might as well toss that bulb.)
If you DID 'leave the leaves', stop watering right now and allow the bulb to dry out for a month or so. Then take it out of its pot, and gently remove any dead leaves and brown 'scaley' stuff on the outside. Nice looking roots indicate a happy, healthy bulb. Repot it, making sure the neck extends well above the soil line. Then place the potted bulb in a cool, dry, sunny spot, water it VERY well, and then water very lightly; new shoots should appear in about a month. When they do, give it a little feeding and begin watering more often, but don't overwater. Flowers should appear in another five to eight weeks, depending on the room temperature. Plant brand new bulbs in early November for your best shot at X-Mas bloom.
(Note: No two sources agree on EXACTLY how to do this. Here's the latest, VERY detailed take from our good friends at the Netherlands Bulb Flower Information Center)
To get rebloom next year, cut the flower stalk off after the blooms have faded, but don't dare touch those green leaves! Treat it like a houseplant over winter—no food and little water. Once the days start getting longer, water it regularly and feed it monthly with a gentle organic fertilizer. In early September, stop feeding and cut way back on the water. Stop watering by October 1st and do it all over again.
You Bet Your Garden ©2004 Mike McGrath