Making begonias happy is so easy that many gardeners miss the mark merely by overindulging these affable plants. To give you some idea of their congeniality, begonias were being grown by indoor gardeners back in the 19th century when heating systems were certainly not streamlined and indoor light levels were low. Here’s the rundown on how you can make your begonias happy. (Pick a begonia based on its needs. See which type is right for you.)
Begonias prefer a well-lit east- or west-facing window. Their foliage can burn in a bright south-facing window, and a north-facing window usually does not provide sufficient sunlight.
If you keep the thermostat above 55°F, your begonias will be infinitely grateful. If that isn’t possible, most begonias will still be OK. But try to limit the chill by stationing them in a bathroom or kitchen. Interestingly, begonias seem to prefer a 5° to 10°F drop from day to nighttime temperatures.
Generally native to humid regions of the world, begonias do not fare well where atmospheric humidity is low. Solutions include hosting your begonias in a humid spot in the house, such as a bathroom. You could also run a humidifier or use a pebble tray. But if you aren’t suffering from chapped lips or dry skin, your begonias will likely be fine.
Give your begonias a drink when the soil is slightly dry but not parched. Overwatering can be a killer, especially during winter when their growth naturally slows down to a crawl.
Fertilize your begonias from March 1 through Thanksgiving; I use fish emulsion, which works like a charm. Do not feed in winter when light levels are low.
Begonias prefer shallow containers, and they like cramped roots. Overpotting can be lethal. When potting, use a light, peaty potting medium with good drainage. Clay or similarly porous containers help the roots breathe.
—Tovah Martin is the author of several books on houseplants, including The Unexpected Houseplant: 220 Choices for Every Spot in Your Home.