For woody-stemmed plants (brugmansia, bananas, tibouchina, and jasmine) expose them to low night time temperatures 40 to 50 degrees and then move them to a cool dark space. Stop watering and if you have the space you can leave the plant standing until the spring (we cut them back as soon as the leaves drop). Two times during the winter you want to give your woody-stemmed tropicals a little bit of water (a half gallon or so), and in the spring expose them to light and start watering (and fertilizing).
That's it - easy-peasy! Cool, dark, and dry = dormant.
#3. Cutting and Propagating
If you don't have a lot of space to overwinter plants, cuttings can be the answer. Unfortunately, this only works for soft-stemmed tropicals.
Soft-stemmed topicals (geraniums, coleus, and plectranthus) can be propagated by clipping off succulent new growth (woody stems won't root) and place the cut end into water. When roots sprout, pot into soil-less mix in a small 4 inch pot. Once potted place them in full sunlight and FEED THEM! Weekly fertilizer is must to keep them healthy. In the spring, after the last threat of frost you can put them out in larger containers or plant them in your garden.
Tropicals can add color and drama to your garden all summer, and with these 3 easy techniques, you can enjoy those tender beauties year after year.