Master Gardener Jan Maas: Keeping annual plants through winter
Being a thrifty type, I like the challenge of wintering over some of my annuals. It helps in the spring, when the nurseries are filled with so many tempting plants, to know that I have saved a few dollars and have some of last year’s jewels to plant out again.
There are several varieties of plants that are amenable to spending the winter in the house. I have had good luck with a number of begonias, some herbs, coleus and geraniums. To be successful with keeping your plants over there are a few things you need to do.
The first step when bringing plants into the house is to make sure they are free of insect pests. There are a couple of ways to do that.
You can just spray them with something like an insecticidal soap or other product that is appropriate for your plants (read the label to be sure). I never spray my herbs, but just rinse them with plain water. Another method is to gather up your plants, cover them with a plastic tent and hang a pest strip inside it for a few days. This is easy and effective, a trick I learned from a fellow master gardener.
Once your plants are insect-free, put them under fluorescent lights or in a bright sunny window. Keep the plants watered, but be careful not to over water. I usually start to fertilize again with a weak solution of liquid fertilizer when the days start to get noticeably longer, about mid-February. The fertilizer, along with the increased day length, will stimulate the plants to put on new growth. That’s when you can take cuttings of your plants (coleus, geraniums, ever blooming begonias) to make new plants for the next growing season. What’s not to like about that!
If you had pots of the non-stop begonias this summer they can be easily wintered over. It’s all right to keep them outside to get a little frost, just enough to wilt the leaves, but not to freeze the soil in the pot. I let the foliage completely die down and remove it. Let the pot dry out and keep it in a dark, cool place.
About the first of March bring them out to a sunny window or put them under fluorescents keeping them slightly moist and they will start to grow again. Be patient; it takes a while for new growth to start, but when it’s time to put out the hanging planters at the end of May, they’ll be ready. I have also repotted these begonias into 4-inch pots and have had them come back without any problem.
The Rex begonias need to be handled a little differently. They have to be divided in order to get more plants. I keep the mother plants moist and under lights during the fall and into the winter. They will continue to put on new growth. After the first of the year they are usually ready to divide into smaller pots.
Try these techniques to save some of your annuals from year to year. Your wallet will be grateful.
There is much more information on growing fruits, vegetables and flowers on the University of Minnesota Extension website at www.extension.umn.edu/gardeninfo at. For help with gardening questions, call 444-7916, leaving your name, number, and question. This is the last week Beltrami County Master Gardeners will be offering this free advisory service this year.