Hi. I've had two large poinsettias for nineteen years now, and three medium-sized for the last nine years. I moved from an apartment that gets a lot of sunlight to an apartment that gets hardly any. That's how I learned that poinsettias have a dormant phase. I bought a high-powered grow light and I have all five of my sleeping plants arranged under it. My poinsettias are very leggy, and I'm wondering if it's safe to trim them back while they are still in a dormant phase. Would it harm them or would it help rouse them from dormancy? For that matter, what other things might help rouse them from dormancy? Any information would be greatly appreciated.
After the plant begins its dormant phase (dropping leaves, etc.) and you've significantly decreased your watering, you can prune back the plant. Usually you can trim each branch back so two or three leaf/branch buds remain. Place the plant in a cool, dry place until Spring. Water sparingly. Keep mostly dry. Once a plant goes into dormancy, it is difficult to bring them out of it. Surely, they respond to increased light duration, as well as, increased temperature as signals that it should come out of dormancy. So, as long as you avoid these potential signals, you should have no worries. Once the overnight temperatures are averaging above 50F/10C you can transition the plant outdoors where it can receive appropriate light levels. Combined with your pruning earlier, the plant should grow in a more compact form.
But I'm trying to bring them out of dormancy. That's why I'm using a grow light. From what you're saying, though, it sounds like it's perfectly safe to trim them back while they're still dormant. Thanks for the information. Does anyone have advice about ways to get them actively growing again?
http://www.hort.purdue.edu/ext/HO-073.pdf This pdf may give you some more clues. Some plants are genetically designed to be either winter or summer dormant. Trying to "trick" the plant into thinking it is one or the other often fails and/or the health of the plant suffers. Having said that, sometimes, over a few years, the timing of dormancy can be shifted one way or the other. I have much experience with my rare succulent plants doing this, as I have ordered many from S. Africa, Australia, etc. where the summer/winter seasons are the opposite of that in North America. Since your Poinsettias are supposed to go dormant in January, trying to bring them out of dormancy in December may prove to be difficult. The drop in light levels obviously triggered dormancy a little early this year, that is all. A little rest is good. Why fight it? You'll likely be rewarded with a spectacular display next year. Good luck, that's all I have to add on the subject. Mark
