If you live in a cold area, many of your container plants will either die or need to be overwintered indoors. With balcony gardens, the easiest thing to do is plant annuals every spring and not worry about a winter garden. Several containers of hardy evergreens can make a winter balcony green, and the rest of the plants can be replanted next year. But if you do need to overwinter plants, there are three techniques you can use to do so.
1. Create an indoor garden. If you have any room indoors (which, as a balcony gardener, you probably don’t!), create an indoor container garden. If you have bright light from a southern window, keep the plants next to the window, but away from any cold drafts. If you have lower light, provide supplemental lighting. The heat and light indoors will keep these plants alive throughout the winter.
The plants will adjust to indoor conditions, and they may look like they’re dying for a while. The plants should bounce back if given good living conditions. To give them a higher chance of success, use a small fan for air circulation and avoid overcrowding (to deter pests and diseases).
2. Take cuttings. Herbaceous tropical plants that are soft-stemmed may do best if you take cuttings and let the mother plant die outside in the garden. Allow the cuttings to develop roots in a glass of water on the windowsill, then plant them in small containers and keep them under a light or near a window. This method will save you money (you won’t have to purchase new plants next year), and it saves more space indoors, as you won’t have to bring in large plant containers and create a whole indoor garden.
3. Let the plant go dormant. Some plants will need to rest during winter. As some plants die, they store energy in their underground tubers and then rest for a period of time before sprouting back to life. Plants such as caladium and cannas grow from bulbs. With bulbs, you can leave them in their plant containers during winter, and keep the soil just barely moist and store the pot in a cool, dark place. You can also dig up the bulbs, wrap them in wet newspaper or peat moss, and place them in a black plastic bag in a cool, dark place indoors. As long as the tubers stay at a temperature of 40 to 50 degrees, they will do fine. Once a month, check the plant bulbs to make sure that they are firm and not drying out. The tubers can be replanted in the spring indoors and gradually acclimating them to the warmth and sun of spring. Depending on the type of plant, the tubers should be brought in either before or after the first frost. Research each plant you have before storing any tubers.
Overwintering will often end in failure, as each plant can be different, and some can be downright picky. Research as much as you can about each individual plant species and how it should be overwintered. Be prepared to lose some plants. Also consider purchasing new annuals each year or collecting seeds so that you don’t have to go to all the trouble to overwinter your plants.