Garden Talk: Extending Our Growing Season

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• With Temperatures Dropping, It’s Time To Bring House Plants Back Inside

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  Just like people, house plants in Wisconsin like to soak up as much of the summer’s warmth and light as possible. But right about now, even if the days are still comfortable, then nights are starting to get chilly. That means it’s time to bring those more tender plants back indoors for the winter.

  Diana Alfuth is the UW Extension Horticulture Educator for Pierce County. She also teaches landscape design at UW-River Falls. She says that just about any house plant will enjoy time outdoors in warm weather. But for them to do well, you need to match their indoor conditions, and those best suited to that type of plant, with where they are outside. “Of course, you don’t want to want to put a low light plant in full sun because it will scorch. Even the plants you would have in a full sunny window in your house like to be in the shade outside because the light is so much brighter outside than it is inside,” Alfuth says. Even if you think the plant has been in full sun indoors, “that glass is cutting a lot of the rays, and even more so if your window is dirty!”

  Time spent outside can really benefit house plants. Especially if you are careful to give them enough water and some fertilizer, “they’ll just bush out, they’re deep green, they’re lush and they’re happy.”

  Right about now, though, we should think about transitioning them back indoors. Alfuth says that even though none of us have likely had a frost yet, the night temperatures are getting into the danger range for our house plants. “A lot of our house plants are basically tropical plants,” she explains, “so when it gets below 40 or 45 degrees, they can get chill injury or really stunted because the cold is just too much.”

  The transition back indoors is similar to the best methods for moving them outside in the spring. Making the move in either direction can be quite a shock for plants. Alfuth recommends gradually getting them used to the new conditions. For example, if the plant has been enjoying full morning sun on the east side of the house, Alfuth suggests moving them around to shade on the north side as an intermediate step. Then, once they are inside, put them in a sunny window to start, even if they will eventually be moved to a lower light spot. “If you can gradually reduce the amount of light that they get, that will give them a little bit of time to adapt.”

  Try to think similarly about the warmth and humidity they are moving into, and ease them into the new conditions. Even though they need to come in from temperatures in the 40s, if the heat is on in your home, that’s going to be a sudden change. “Anything you can do to gradually make those changes will help the plants handle that shock a little bit more.”

  Even with a gradual transition, don’t be surprised if you see some changes in your plant. One example is a fig tree, or ficus, which doesn’t like any significant changes in its environment. “They just get all dramatic and they drop their leaves,” Alfuth laughs. In general, leaves grown in high light conditions are thicker, so in a case like that, the leaves that replace those that drop are likely to look more tender and delicate, but that’s normal. In fact, the thinner leaves are more able to photosynthesize the lower light, so it’s good that they replace the others.

  Sometimes, hitchhikers will come indoors along with the plants. In fact, Alfuth says, “I did that one year, I brought in the plants and all of a sudden there’s a little frog hopping across the dining room floor!” When temperatures drop, Alfuth says that all kinds of critters are programmed to find a safe place to overwinter. That can be under a flower pot, attached to the bottom of leaves, or burrowed into the dirt. But then once they are indoors, it is warmer, and they become active again. Alfuth says that wasps are commonly found inside because of that.

  A few techniques are to cover the plant for the last few weeks outdoors to discourage insects and other animals from getting inside. That can mean floating row covers for the foliage, or even aluminum foil over the top of the soil. One way to evict critters from potted plants is to soak the pots in a tub of lukewarm water for about 15 minutes. When the soil gets warm, any pests may crawl out and you can deal with them right away.

  A period of quarantine once the plants are inside is also a good idea. Alfuth suggests a laundry room, or another area of the house where they aren’t able to affect other plants and are contained. This is especially important with pests like aphids, which can spread quickly from one plant to another. And because aphids feed on the plants, they can be an additional stress during that time of transition.