Growing Indoor Plants Following is the second set of responses energy saving lampfrom Tibor Fuchs, the president of the Metropolitan New York Chapter of the Indoor Gardening Society of America who responded to readers’ questions about Grow lights and keeping them alive inside.

Sometimes, when you water faithfully, fungus takes hold, growing on top of your potting soil, especially if it’s old. Fungus gnats result and though the adult, flying forms are reputedly harmless, the larva may eat the roots of some plants. If, when you water, you see tiny wriggling, wormlike threads floating up out of the soil, that’s them. Pour them off and spray the soil with a non-toxic insecticide like our alcohol/water/Dawn combo or a Pyrethrin-based product.

Better yet, here’s a great tip I got off the Internet: Go to a party store and buy yellow plastic cups. Use a heated screwdriver or a soldering iron to melt a small hole into the center of the bottom of the cup. Pull a length of twine through into the cup and tie a knot. Using a small brush, paint the cup all around the outside with STP Oil Treatment. Hang the cup near your plants or dispense with the hole and string and just place it on the plant shelf. Use one per shelf. Fungus gnats, whitefly and even ants Grow lights are strongly attracted to the color and smothered by the oil. Replace the cups after the oil dries out. This method is economical and really seems to work. You should be gnatless in no time.

Lots of people wanted a list of plants that freshen the air. Such a list is available on Wikipedia. The book to read on the subject is, “How to Grow Fresh Air: 50 House Plants that Purify Your Home or Office,” by B.C. Wolverton (New York: Penguin Books, 1996).

Forget heliconias. If you really have “lots” of north light, you have the same light conditions as the lower canopy and floor of a rain forest. You can grow orchids, including phalaenopsis, oncidiums (like maculata and “Sharry Baby”), pahiopedilums and Ludisia discolor, a creeping terrestrial “jewel” orchid with marvelous orange-veined leaves on a dark brown background and never-fail flowers (I recently had a piece of mine Grow lights drop to the floor unnoticed energy saving lampwhere it budded and flowered without any water or notice from me).