Overwintering tropical plants can it be done in zone 4?

  

      Three Ways to Overwinter Tropical Plants
By Marie Iannotti  About gardening.com
 
       It's hard to resist those tropical beauties in the garden center each spring.  We've all succumbed to the imposing leaves of elephant ear (Colocasia) and the striking colors of cannas. Trumpet-flowered Mandevilla grows nicely in a container and can cover a fence in never ending color, at least until frost.  Then there are banana trees, which will probably never produce bananas for us, but make quite the statement in the garden none the less.  And who isn't charmed by Brugmansia, or Angel's Trumpet, with its foot-long trumpet horn flowers that obligingly hang upside down, so we can fully take in their heady scent.
         These tropical plants add a touch of the exotic to our gardens, providing a taste of warmer climates for however long our summers may last. But they don't come cheap and to grow a really impressive specimen takes years. Growing them as annual plants seems a waste of not just all the resources you put into buying and caring for the plants, but also the plants themselves. However if you want to enjoy your tropical plants for years to come, you will need to find somewhere safe to store them for the winter. 
       That can vary from plant to plant. Some plants will happily go dormant, grateful to have the winter off and a little downtime to regain their stamina. Others make excellent indoor plants, if you have a spot with enough sun and you can control the heat and humidity. It's not easy making an outdoor plant happy indoors, especially in the winter.
       Days are short, indoor air is dry and there are no natural predators for houseplant insects. But it is possible to over-winter your tender tropical's.  Here are 3 ways to do it and which plants fare best for each method. 
        Many gardeners start their elephant ears as a bulb, but don't consider saving them over winter as bulbs. This is arguably the easiest way to over-winter plants and all the bulbs or tuberous plants, like cannas, caladiums, and even dahlias, are good candidates. You need to wait until the leaves have been browned by a light frost, then lift the plants and put them somewhere shaded and sheltered, so the bulbs can dry out for several days.
         Once dry, brush off as much soil as you can, trim the leaves back to a couple of inches and store them in a box with peat of saw dust or wrap each bulb in a sheet of newspaper and tuck into a box. Keep them cool and in the dark, checking periodically to see if any are starting to rot or if they are starting to shrivel. Dispose of any rotting bulbs and spray a little water onto the peat or paper, if they are drying out. Here's more about storing tender bulbs for winter.
        You can repot them a month or 2 before your last frost, to get a head start on the growing season, or save them to plant outside, as soon as the ground warms and no frost threatens. This method takes up minimal space and most bulbs and tubers make it through the winter just fine. Since the bulbs will produce more offset bulbs, saving them year after year will also mean more bulbs each year, to plant or give away.
      Not all tropical plants make good houseplants, but there are plenty that do. Some, like canna, seem to attract every aphid to come indoors with them. And very often we just don't have the growing conditions a tropical plant needs to continue growing and looking attractive indoors.  If you want to give it a try, start caring for them before you bring them inside. Carefully inspect the plants for any sign of pests or disease and treat accordingly.
You might want to cut it back by one-third to one-half, to make it more manageable.
       Then find the brightest window you have and make a space for your plants to settle in. Make sure they are away from drafts and from excessive heat sources. Bringing your plants indoors while the windows are still open at night will give them the best chance of acclimating.  If you don't have a sunny window, you can use artificial plant lights. Another concern is the dry air in winter. Keep a spray bottle handy and mist your plants daily.
      Some great candidates include:  banana, begonia, brugmansia, fuchsia, and mandevilla. Your plants probably won't thrive and they may not bloom, but they should survive with minimal stress. Here are more tips for bringing outdoor plants inside.
       This method of over-wintering tropicals is a little more hit and miss than simply storing them as bulbs, but it's worth a try. It helps if the plants are already in containers, but you can always lift them and pot them up at the end of summer.  After a light frost, cut the tops back to 6 - 8 inches and only water when the soil looks bone dry. Move the containers to a cool, dark spot that will stay above freezing, but below about 50 degrees F.    Check them periodically, to see if they need a small drink of water, but water sparingly. You can resume regular watering about the same time you begin to start seeds. At that point, you should see new growth starting and you should move the containers into the light. (Don't move them directly into bright light immediately or your could burn the tender, new leaves.)  When you see several inches of new growth, you can also give your tropical plants a little fertilizer.  Start to harden them off, after all danger of frost.
Plants that handle this type of winter care well include: banana, begonia, brugmansia, caladium, canna, mandevilla, and tender ornamental grasses.  Give it a try if you have room.  Till next time, this is Becky Litterer from Becky's Greenhouse Dougherty Iowa