Master Gardener Corner: Overwintering Annuals
This article is part of a weekly series published in the Batavia Daily News by Jan Beglinger, Agriculture Outreach Coordinator for CCE of Genesee County.
Master Gardener Corner: Overwintering Annuals Originally run week of September 12, 2017 When September rolls around, gardeners know that the end of the gardening season isn’t far off. After that first frost hits, it usually does in most garden plants, especially the annuals. Temperatures below 50 degrees F can put the chill on tropical plants that decorated our containers and window boxes. If you are lamenting the loss of your annual summer bloomers, try taking some of them inside this fall. With minimal effort you could have a blooming beauty all winter and save yourself a few bucks next spring. There are many techniques for saving annuals, tropical plants and tender succulents. The technique you choose depends on the plant. Tender succulents prefer warm and dry winters. Some tropical plants can be overwintered by forcing the plant into dormancy. Foliage plants tend to be better candidates than flowering plants because they adapt more quickly to indoor conditions. Many plants we consider to be annuals can be easily potted up and brought inside or propagated by stem cuttings. To give yourself and the plants the best shot for success, bring plants inside before a frost. Pick only healthy plants as struggling plants are unlikely to survive and will only make more work for you. Check for bugs and other hitchhikers. During the winter, lower light levels can be a problem. Help plants get used to indoor light levels by putting them in a shady spot for about a week. Don’t be alarmed if some plants drop their leaves once inside. They should sprout new foliage. If you don’t have a bright sunny window, you can always use grow lights. Many succulents and cacti will do well indoors if you have a sunny window. If you grew them in containers you may be able to bring in the whole container, depending on your window space. Otherwise pick your favorites and pot them up using a commercial soil mix labeled for cacti and succulents. With such a wide assortment of “annuals” available for sale, you may have to do some research to figure out which annuals can be successfully wintered over. Many of the plants sold as annuals are actually tender perennials. They are perennial somewhere, but they can’t handle our cold winters. Coleus, geraniums, impatiens and wax begonias winter well indoors. Try potting them up for the winter. Cut plants back by half, pot in a soilless mix and place on a sunny windowsill. However, true annuals such as basil and zinnias will not last long inside. To save whole plants, such as impatiens, start with healthy plants and a clean container with good drainage. Dig about 2 inches wider than the plant base and 4 to 5 inches deep to prevent root damage. Gently lift the root ball from the ground. Pot each plant in a container big enough to hold all the roots comfortably. Inspect for insects and clean off any dead stems, flowers and leaves. Water well and make sure the container is draining properly. For blooming plants you can use a little fertilizer, about quarter strength of the recommended dosage. Lightly fertilize again about a month later if the plant is still
blooming. Put in a bright, sunny window. To make plants easier to handle, you can cut plant tops back by a third to half. Pinch growing tips regularly to encourage branching and to help keep them from getting too leggy. Some plants may continue to grow, bloom and look good, but others may start to go dormant and not look that great by mid‐winter. Once spring arrives these plants can be put back into the garden after the last spring frost and night temperatures stay above 50 degrees F. Many annuals such as impatiens, coleus, plectranthus, geranium and sweet potato vine can be saved by stem cuttings. Some can be simply put in a glass of water where they will root. Others need some kind of medium. Using a sharp pair of clean scissors, take stem cuttings from the terminal ends of the shoots, 3 to 5 inches long. Remove the leaves on the bottom third to half of each stem. Dip the cut end into a rooting hormone (not always necessary) and insert the cuttings one inch deep into a container filled with damp perlite, vermiculite, or sand. Cover the container with a clear plastic bag to create a tent and secure with a rubber band around the base of the container. Place the cuttings in bright, but indirect light. Keep the soil moist. Most cuttings will root in 6 to 8 weeks. To see if they have rooted, gently tug on the stem tips. When the roots are at least one inch long, they can be transplanted into four inch pots. Use a good houseplant soilless potting mix. Plants can then be placed into direct sunlight. To keep them from growing lopsided, give them a quarter turn about once a week. Always take more cuttings than you think you will need since some will not root. You may not be able to successfully over winter every plant you bring in, but half the fun is in the trying. See what works for you and build on that next year. If you are successful overwintering your annuals you will have nice mature plants to put out next spring. Resources for this article include: U.S. National Arboretum, Proven Winners, University of Nebraska, University of Illinois, and Master Gardener Lynette Siverling
Master Gardener Corner: Overwintering Annuals Originally run week of September 12, 2017 When September rolls around, gardeners know that the end of the gardening season isn’t far off. After that first frost hits, it usually does in most garden plants, especially the annuals. Temperatures below 50 degrees F can put the chill on tropical plants that decorated our containers and window boxes. If you are lamenting the loss of your annual summer bloomers, try taking some of them inside this fall. With minimal effort you could have a blooming beauty all winter and save yourself a few bucks next spring. There are many techniques for saving annuals, tropical plants and tender succulents. The technique you choose depends on the plant. Tender succulents prefer warm and dry winters. Some tropical plants can be overwintered by forcing the plant into dormancy. Foliage plants tend to be better candidates than flowering plants because they adapt more quickly to indoor conditions. Many plants we consider to be annuals can be easily potted up and brought inside or propagated by stem cuttings. To give yourself and the plants the best shot for success, bring plants inside before a frost. Pick only healthy plants as struggling plants are unlikely to survive and will only make more work for you. Check for bugs and other hitchhikers. During the winter, lower light levels can be a problem. Help plants get used to indoor light levels by putting them in a shady spot for about a week. Don’t be alarmed if some plants drop their leaves once inside. They should sprout new foliage. If you don’t have a bright sunny window, you can always use grow lights. Many succulents and cacti will do well indoors if you have a sunny window. If you grew them in containers you may be able to bring in the whole container, depending on your window space. Otherwise pick your favorites and pot them up using a commercial soil mix labeled for cacti and succulents. With such a wide assortment of “annuals” available for sale, you may have to do some research to figure out which annuals can be successfully wintered over. Many of the plants sold as annuals are actually tender perennials. They are perennial somewhere, but they can’t handle our cold winters. Coleus, geraniums, impatiens and wax begonias winter well indoors. Try potting them up for the winter. Cut plants back by half, pot in a soilless mix and place on a sunny windowsill. However, true annuals such as basil and zinnias will not last long inside. To save whole plants, such as impatiens, start with healthy plants and a clean container with good drainage. Dig about 2 inches wider than the plant base and 4 to 5 inches deep to prevent root damage. Gently lift the root ball from the ground. Pot each plant in a container big enough to hold all the roots comfortably. Inspect for insects and clean off any dead stems, flowers and leaves. Water well and make sure the container is draining properly. For blooming plants you can use a little fertilizer, about quarter strength of the recommended dosage. Lightly fertilize again about a month later if the plant is still
blooming. Put in a bright, sunny window. To make plants easier to handle, you can cut plant tops back by a third to half. Pinch growing tips regularly to encourage branching and to help keep them from getting too leggy. Some plants may continue to grow, bloom and look good, but others may start to go dormant and not look that great by mid‐winter. Once spring arrives these plants can be put back into the garden after the last spring frost and night temperatures stay above 50 degrees F. Many annuals such as impatiens, coleus, plectranthus, geranium and sweet potato vine can be saved by stem cuttings. Some can be simply put in a glass of water where they will root. Others need some kind of medium. Using a sharp pair of clean scissors, take stem cuttings from the terminal ends of the shoots, 3 to 5 inches long. Remove the leaves on the bottom third to half of each stem. Dip the cut end into a rooting hormone (not always necessary) and insert the cuttings one inch deep into a container filled with damp perlite, vermiculite, or sand. Cover the container with a clear plastic bag to create a tent and secure with a rubber band around the base of the container. Place the cuttings in bright, but indirect light. Keep the soil moist. Most cuttings will root in 6 to 8 weeks. To see if they have rooted, gently tug on the stem tips. When the roots are at least one inch long, they can be transplanted into four inch pots. Use a good houseplant soilless potting mix. Plants can then be placed into direct sunlight. To keep them from growing lopsided, give them a quarter turn about once a week. Always take more cuttings than you think you will need since some will not root. You may not be able to successfully over winter every plant you bring in, but half the fun is in the trying. See what works for you and build on that next year. If you are successful overwintering your annuals you will have nice mature plants to put out next spring. Resources for this article include: U.S. National Arboretum, Proven Winners, University of Nebraska, University of Illinois, and Master Gardener Lynette Siverling
