Many gardeners, including myself, like to have plants in the garden that while technically are perennials, they will not survive our winters without some protection. We grow these tropical and semi-tropical plants because we want to try something new or perhaps because we like the beautiful summer flowers and/or foliage they produce. Brugmansia, (Angel’s Trumpet), is a good example. These plants thrive in our summers, growing quickly and providing us with beautiful flowers that are shaped like long trumpets and often with a delightful fragrance.
If the Brugmansia is in a pot, perhaps the pot can be brought indoors if there is a sunroom. However, Brugmansia plants grow quite large and few homes would have space for one. I had a neighbor that would cut his Brugmansia in half, (due to the large size), and bring it into his unheated garage. While the leaves fell off, the roots survived and in the spring, he moved it outdoors. Brugmansia plants are very easy to start from cuttings and if the stems are cut in lengths of 5-6 inches and placed in a jar of water near a window, most of them will root. It is important to make the cuttings before a frost and remove the leaves before placing the stems in the jar. Once roots appear, the stems can then be planted in a small pot and kept until planting time in the spring.
Coleus are very popular summer foliage plants and they are also very easy to root from cuttings. Simply make cuttings 3-4 inches long and put them in a plant tray with a medium of vermiculite or perlite. The cuttings need to be made before a frost. Remove all the leaves except those at the top and keep the tray under a grow light. When the plants begin to grow, they will need to be transplanted to small pots with an all-purpose potting soil.
I have a non-winter hardy Agave as well as other plants in pots that are not winter hardy. The Agave, especially, is one that I do not want to lose and so I take it into our garage before a frost. While our garage is unheated, the Agave has survived for perhaps five years. I place it near a window so it does get light and I water it lightly, maybe once or twice during the winter.
One of the limiting factors we have with bringing tropical and semi-tropical plants indoors is our low light in the winter. With a sunroom, this would not be an issue, but without one, the plants will probably stretch for light and become very spindly. Before any plants are brought indoors, spray them with water thoroughly to remove any insects or pests that may be hiding in the foliage. Keep the pot away from a heating vent and put in an area with as much light as possible. Be sure to bring the pot indoors before a frost.
If bringing a pot indoors or in a garage is not an option, try moving the pot to a protected area against your house. Plants in pots will be more susceptible to winter damage than those in the ground. If the plant is semi-hardy here and in the ground, mulch the roots with a large pile of leaves or garden compost This might work if the winter is not too severe. If the plant does not survive but has provided you with pleasure all summer, you deserve to have a new one in the spring!