All I wanted was just one more dinner on the deck, surrounded by flowers and foliage, before I dragged in all my houseplants. But, no . . . There I was, caught in mid-October, saving the plants. Is this familiar, anyone?

The perfect among you did this correctly, so the plants would have a gradual transition. Then they wouldnt get "plant shock" and drop their leaves.

Abrupt changes— from cold outdoor temperatures to dry indoor heat—cause that. If you did it my way, and the plants faced a 15-degree difference, consider keeping your house cold for a while. Just wear wool!

The light difference is also shocking for them. Again, they adjust by dropping leaves. Where you put the plants is important because each plant has a particular light need. Most houses dont offer perfect situations, and you might need supplemental lighting.

Houseplant books get into "foot candles" (technically, how much light a candle gives off one foot from the flame). You could buy a light meter to measure from low (1,000) to high (2,500) foot candles. But for practical purposes, Ill use the language of most plant tags: bright, indirect, low light, or full sun, part sun, partial shade, shade. Lets translate:

Bright light/full sun: Within 2 feet of an unobstructed sunny south or west-facing window. Its for cacti and succulents but burns many others.

Indirect light/part sun: Within 2 feet of a sunny east window, or a few feet from a southern or western one (about four hours of sun.). Suits most houseplants best.

Low light/shade: North-facing windows; other windows shaded by trees, or tabletops in the room. OK for a few tough standards like snakeplants and cast-iron plant.

Types of lighting

My plant groups in the shady windows need supplemental lighting. But what kind and where to find it? Normal incandescent light bulbs add light but are just too hot.

For decades gardeners have grown plants under inexpensive, cool white fluorescent shop lights, or a combination of cool/warm 40-watt tubes. Use two bulbs for medium light and four for bright. HID (high intensity discharge) lights also offer a broad light spectrum—often used to grow seedlings.

Some grow-light bulbs are like spotlights and cover fewer plants each. Be careful, as some are actually incandescent and way too hot. Halogen lights offer a pleasing white light, but their limited spectrum is not optimal for plant growth. Some do help with the SAD problem (seasonal mood disorder).

Newer LED lights are the most energy efficient but more expensive, and you need a DC 12V power transformer. The best solution may be a new generation of grow lights and SAD lights.

Then there is the decorating problem to be solved. How can we light the plants without the room looking like a shop? I will check online and in lighting stores to suit plant and people needs. I hope you find the right solutions, for you and your houseplants.

Sally Cunningham is a garden writer, lecturer and consultant.