I think I’m going to have to reset my plant lights if I want my Christmas cactus to bloom.

One of the plants I ordered from Logee’s last fall was a Christmas cactus, “Christmas Flame,” with beautiful peach-gold flowers – at least, according to the catalog picture. It’s healthy, glossy, and generally looks as if it really enjoys my cool plant room, but there’s not the slightest sign of buds. And I’m afraid I know why.

Christmas cactus are day-length – or more accurately, night-length — sensitive. They need cool temperatures and at least 12 hours a day of uninterrupted darkness to form buds. Cool is fine; my plant room is thermostatted to 65° daytime and 55° nighttime temperatures. Night length? Well, I’ve had the lights programmed to be on 16 hours a day, to make up for the fact that at this time of year the plants are almost totally dependent on artificial light. Cool temperatures alone are enough for some cultivars, but apparently not for this one.

So I’ve reset the light cycle so the lights go on at 8 am and go off at 8 pm. I’ll have to keep the door to the plant room closed in the evening, and I may have to move the plant away from the window for the next full moon. (Not this one; we’re predicted to have cloudy skies for the next few days.) I don’t think the snow reflects enough light from my bedroom window to be a problem, and the nearest street light is at least a tenth of a mile away and not on the same side of the house as the plant room. Aurora? Not likely to be bright enough to cause a problem.

Supposedly it takes 6-8 weeks of long nights to get the buds going, so it’s likely to be February before I know if my cactus is going to bloom. Meanwhile the jasmine has put out a flower, the first narcissus opened today (and I can actually smell it) and the potted rose bush is putting out a new flush of growth. It may be winter outdoors, but the lights and the plants are going great indoors.

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