Bringing Plants Indoors | Knowledge & Wisdom

There are two temperature ranges that will determine what you can grow in a given location. … The low temperature range would be a night reading of just above freezing and a daytime reading in the mid-40s Fahrenheit. In that range, you could winter over geraniums and delicate perennials. … The second temperature range is a night low in the high 30s and an average daytime reading of 50° or higher. In that range, with good light, you can grow just about anything. … A cold garden is definitely not the place for small, young plants. For older established plants, however, the cold environment provides an enforced dormancy that often leads to increased vigor when temperatures warm in the spring. …

The word on watering the cold indoor garden is caution. Little water is lost through transpiration from the leaves at low temperatures, and even less through evaporation from the soil. If the plants are of a good size and growing in containers of more than eight inches in diameter, weeks may go by between waterings. The effects of overwatering in the cold are even more devastating than at higher temperatures. …

[Another] point about cool culture of houseplants grown in natural light: Don’t feed them. At these low temperatures, little or no growth is taking place; feeding with fertilizer can be harmful and sometimes fatal. Put away all the yummies until March, when your cool garden begins to warm.

–Helen Tower Brunet, Yankee’s gardening editor, November 1978