Proper lighting and an adequate amount of water might prompt withering dorm room plants to thrive, horticultural experts say.

Lisa Dawn White, facility manager at the Penn State horticultural research farm, said most houseplants are from tropical or semi-tropical environments. They have adapted to a warm, arid, indoor environment and would be unable to survive a cold Pennsylvania winter outdoors, she said.

"One of the greatest effects that winter has on houseplants is the decreased level of light," White said.

Kathleen Brown, professor of post-harvest physiology in the department of horticulture, said, "Winter is stressful because the light is lower both in intensity and duration." The lack of light leads to a decrease in the frequency of photosynthesis, which yields less energy production for growth, Brown said.

Toni Bilik, Penn State master gardener coordinator, said direct heat also contributes to unhealthy houseplants.

Brown said, "Heated air has lower relative humidity which tends to dry out the plants." An overheated environment can have damaging effects on plants, she said.

"If the temperature is cooler, then the effects of lower light and lower humidity are not as bad," Brown added.

Bilik suggested looking for brown, pale green and yellow leaves, as well as leaf-drop and weak growth to determine a houseplant's health. Brown cautioned plant owners to be alert for insect infestations.

White said that when houseplants stop growing or fail to look as vibrant as they had in other seasons, it might indicate their health is declining. She also warned plant owners not to overlook tiny spider webs or waxy, sticky residue on leaves.

When trying to cure an unhealthy plant, White suggested researching the environment the plant has evolved in and replicating that environment as closely as possible.

"This is hardly as complicated as it sounds," she said. "Most house plants available at the garden center will do just fine in the average home environment, given attention to their most basic needs."

In response to the problems resulting from a limited amount of light, White urged plant owners to purchase supplemental lighting for their houses. Either full-spectrum bulbs or fluorescent fixtures will be beneficial to houseplants, she said.

"Many houseplants will slow down in response to limited light. . . . Fertilization will not be necessary," White said. She suggested supplementing plants with small doses of compost because it breaks down slowly. Bilik also emphasized cutting back on the amount of fertilizer used during winter months.

Damage due to inconsistent temperatures also is avoidable. Bilik said, "If possible, keep plants in an area where temperatures stay between 60 and 70 degrees." Brown warned people to keep plants from temperatures below 50 degrees.

White said most importantly, people should adjust their watering routine to insure their plants' survival. Environments that are drier in the winter compared to other seasons call for plants to be watered more frequently and vice versa.

Another practice that increases the humidity around plants is to situate plants in saucers with stones in them so excess water can drain. Moisture is absorbed by the stones and released around the plant, Brown said.

This practice also allows excess salts to drain freely from the container and prevents a build up that could lead to a white crust on the surface of the plant, White said.

In order to provide plants with optimum care both, White and Bilik encouraged plant owners to purchase inexpensive reference books to research their plants.

"Experiment and have fun with your plants. Get to know them by inspecting them regularly, and you will easily spot problems long before they threaten the life of the plant," White said. "Most problems that arise with houseplants over winter are not related directly to the season itself but more so because the cultural practices and requirements for their maintenance have not been modified accordingly."