Martha Stewart: A little education on the grades of olive oil

Q: How do the grades of olive oil differ, and which kind should I use for everyday cooking?

A: Extra-virgin olive oil, made from the first pressing of olives after harvest, has a bright, fruity taste. Neither heat nor chemicals are used to extract the oil (hence the labels "cold pressed" or "cold extraction"), so it is the freshest and the most healthful olive oil. Virgin olive oil is also extracted without heat or chemicals but is more acidic than extra-virgin and may not be from the first pressing. Bottles labeled "olive oil" or "pure olive oil" typically contain blends from second or third pressings, with virgin or extra-virgin oil added for flavor.

In the past, the price of extra-virgin olive oil limited its use, but affordable bottles are now widely available and are even preferred. Ideally, you should keep two kinds of extra-virgin oil on hand: an inexpensive one for cooking and a premium one for dishes that will showcase its nuanced flavor and aroma. Both characteristics diminish when an oil is heated, so use the everyday one when sautéing, grilling, making sauces or baking. Serve your best oil drizzled over roasted vegetables, whisked into a vinaigrette, tossed with pasta or simply on its own with a loaf of crusty bread.

Oils can turn rancid with exposure to heat or light, or simply with age. To prevent this, store olive oils in a cool, dark place; they will keep for about a year.

Q: I buy an amaryllis plant every holiday season. Is there a way to get it to reflower the following year?

A: If cared for properly, amaryllis will last up to 40 years, producing larger leaves and multiple stalks of flowers over time. The trick is to simulate the plant's natural environment, in which the weather cycles trigger bud formation and blooming. Once the flowers are spent, cut their stalks off with pruning shears. The bulb should be nestled in soil up to its shoulders in a container (with drainage holes) that is two inches wider than the bulb. If you need to repot, work gently, disturbing the roots as little as possible.

In the winter, place the amaryllis in the sunniest spot in the house, watering and feeding it with a balanced fertilizer, following the instructions on the product's label. The straplike leaves, which produce the energy needed to form the flower bud, should emerge. In the summer, move the plant outdoors, and continue this regimen. About 18 weeks before you'd like the bulb to bloom (for holiday blossoms, that's early August), stop watering and fertilizing the plant entirely. Move it indoors to a dark, dry place no warmer than 68 degrees (basements work well) for at least eight weeks. About 10 weeks before you'd like the plant to bloom, bring it back into a warm, bright room, and resume watering. Keep the soil barely moist until the flower bud emerges from the bulb, and then keep soil evenly moist. The bloom will last the longest in a cool area that's bright but not in direct sun. When the flowers fade, your amaryllis can begin the cycle anew.

Q: Is it necessary to have a humidifier? How can I clean it properly?

A: When heating systems are running continuously, the air dries out and humidity levels drop, which can lead to parched throats, itchy eyes and respiratory problems. A humidifier helps keep the humidity at a comfortable level, usually 30 to 50 percent.

Cleaning the humidifier regularly is a must, as mildew and mold can grow in just a few days. Change the water daily, using distilled or demineralized water; both contain fewer minerals than tap water and will reduce buildup. After emptying the tank, dry it completely. Clean the various parts a couple of times a week, following the manufacturer's guidelines. In general, use a vinegar-water solution and disinfect with diluted bleach. After cleaning, rinse thoroughly and refill the humidifier with water.

Questions should be addressed to Ask Martha, care of Letters Department, Martha Stewart Living, 601 W. 26th St., 9th floor, New York, N.Y. 10001. Questions may also be sent by e-mail to: mslletters(at)marthastewart.com. The (at) represents the "at" symbol on your keyboard. Please include your name, address and daytime telephone number.)