Consider artificial light
If you don't have enough sunny windows or the budget or inclination to indulge your plants with new decor, there's always artificial light. For example, fluorescent lights are inexpensive to buy and run, give off lots of light in an acceptable spectrum (which means mostly blue and red light waves) and don't burn plant leaves unless the leaves touch the tubes. A simple, two-tube lamp using 120-centimetre, 40-watt tubes suspended 15 to 30 centimetres above the plants will keep most of them happy. You don't need special horticultural tubes; a pairing of one ordinary cool white with one warm white fluorescent tube per fixture will do the job nicely. For plants that need lots of light, such as miniature roses, some orchids and most cacti, use a four-tube fixture. Fluorescent lights can even be hidden from view inside bookshelves, in the basement, in the attic, under stairs or in a closet—I have a light garden in an unused fireplace.
Any artificial lighting for plants should be on a timer: 14- to 16-hour days will convince most plants it's still summer, stimulating healthy growth and abundant flowering. Exceptions are plants such as poinsettias and Christmas cacti, which will grow but not bloom under long days of light. Give them their own lights and set the timer for 10 hours; then watch them bloom their little hearts out.
Food and drink list
Age-old advice says never fertilize plants in fall or winter, but that was before artificial light. Don't feed plants that aren't getting enough light: this will encourage weak, straggly growth. Do feed those that are actively growing, following the schedule on the product's label. Many indoor gardeners apply one-quarter of the usual recommended dose of soluble, all-purpose fertilizer to all their plants at each watering throughout the winter. This provides enough fertilizer for plants growing under lights without harming those that are growing under weaker natural light.
How much water plants require during winter depends on their growing conditions. Many people assume they grow more slowly in winter and therefore need less water. But if the air is really dry, plants will transpire so heavily that they may require more water than they would in summer, whether they're noticeably growing or not. The usual watering strategy still works: wait until plants dry out slightly before watering thoroughly. Check them every three or four days; sink your finger into the soil to the second knuckle to see if it feels dry. If so, water until the excess runs into the saucer.
Image: A bright pink cyclamen specimen. Photography by Aleksandra Szywala.