Posted by: Sarah Schweig, Broomfield County Extension
I have houseplants year-round. This time of year, though, I have a house full of plants. Fueled by a love for propagation, a desire to collect unique specimens, and a habit of forming unreasonable attachments to said specimens, it always feels like I have more plants this year than the last.
By now, any plants that were vacationing outside for the summer have been inside for quite a while. If you, too, took the ‘pile them all on the nearest well-lit table’ approach, that’s actually not a bad start. Just as we introduce plants to the outdoors gradually, plants need time to adjust to the move indoors. However, if you’ll need to use that table in the next five months, you may be looking for longer-term winter locations for your houseplants.
|Photo: Esther Knox
As you investigate your plants’ seasonal home options, make sure to take stock of how your indoor environment has changed with the season. You may even find plants that are inside year-round would benefit from temporary relocation.
Changes in Lighting
In the northern hemisphere, the sun is lower in the sky during the winter; the sun will rise south of true east and set south of true west. Sunlight is less intense, and objects cast longer shadows. Combine these facts with less total hours of sunlight, and some plants that were receiving sufficient light may no longer be. On the other hand, if deciduous trees provided shade, they have now dropped their leaves. If you experience regular snowfall, factor in the increase in reflected sunlight. Make sure you know the individual light requirements for each plant, and strive to maintain consistency or make gradual adjustments. PlantTalk Colorado offers guidance on what kind of light to expect, depending on the orientation of your windows and seasonal changes here.
It’s worth noting that some flowering houseplants rely on seasonal environmental signals like photoperiod. The popular Christmas cactus (Schlumbergera bridgesii), for example, is signaled to bloom by (consistently) prolonged periods of darkness at night. If your Christmas cactus is placed near artificial lights that are left on at night, the interruption of the dark period will keep them from blooming.
Changes in Temperature and Humidity
Make sure plants are not placed near heating vents or too close to drafty windows or doors. While some houseplants can adapt to a range of temperatures over time, none are immune to the stress caused by rapid temperature fluctuations. This stress makes plants more susceptible to pests and diseases, and the especially dry environment near a heating vent, for example, is optimal for some common houseplant pests like spider mites.
Compared to the indoor environment in a Colorado winter, most houseplants would benefit from increased humidity. To increase and stabilize relative humidity in the immediate environment, you may consider grouping plants together. Keep in mind that good air circulation is also important. Other strategies like pebble trays keep pots and roots out of water but increase humidity around the plants as the water below evaporates. Unless done very frequently, misting plants has little effect on relative humidity and may increase the risk of foliar diseases.
Dialing in on the winter care routine for your houseplants may take some observation and adjustment, but what are 4:30pm sunsets for? Set yourself up for success by researching the needs of your plants, and start with the right site.