Plants may need time to adjust when moved indoors for winter

Nighttime temperatures in the 50s are a signal that fall has arrived, even though the high daytime temperatures are breaking records. Still, it is time to think about moving inside some plants that have been out all summer.

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Several key factors must be taken into account when bringing a plant into the house for the winter, and that should be considered when buying new houseplants. Although different houseplants have different needs, light, temperature, humidity, water and the soil will affect how well a plant grows or adapts to its new surroundings.

Of all the factors affecting growth, light is the most important for houseplants. I had a ficus tree that we moved outside every summer. When the ficus was moved back inside, it would lose all its leaves because of the change in light levels. In a few weeks, however, it would be full of leaves again.

There are a number of symptoms that indicate a plant is not receiving enough light: The plant becomes leggy or spindly; the internodes (spaces between the leaves) on the new growth are much longer than the internodes on the older part of the plant; new leaves are larger than old leaves; and new leaves are a lighter color than older leaves; and the older leaves are dying or falling off the plant.

Houseplants are divided into four groups based on light requirements: low light, which is 25 to 75 foot-candles; medium light, 75 to 150 foot-candles; high light, 150 to 1,000 foot-candles; and very high, above 1,000 foot-candles. A foot-candle is the amount of light cast by candle on a white surface one foot away in a completely dark room. For plants that require medium to high levels of light, an artificial light source is usually necessary for the plant to do well. Another way to solve the problem is to increase the number of hours a plant receives light.

Give the plants a few weeks to adapt after moving them inside. This is done by gradually moving the plants to more and more shade.

If the plants are in full sun, move them to partial shade for a week or so. Then they can be moved into full shade for a week or two. This will allow them to adjust to the light levels inside a house.

The next most important factor affecting houseplants is temperature. Most houseplants can tolerate temperatures down to 55 degrees. I try to move my plants indoors when the temperature is around 55 at night. Most houseplants come from tropical or subtropical areas of the world. Therefore, they like temperatures in the range of 58 to 86 degrees. However, the best range is 70 to 80 degrees during the day and 65 to 70 degrees at night.

Because most houseplants come from the tropics or subtropics, they are accustomed to high humidity. Houseplants do so well outside here because of our high humidity. When we move plants from outside to indoors, they are moving into an area with lower humidity. Most homes have a humidity level of 10 percent to 30 percent. So we should ensure that the plants have the right humidity levels.

Plants that are placed close together will create a micro-environment with a higher relative humidity. Also, shallow containers filled with water and lava rocks or gravel will provide an increase in relative humidity because of evaporation.

A humidifier can also be used to increase humidity around the plants.

The last two factors that affect houseplants are watering and the soil that the plants are growing in.

Improper watering is the next biggest problem I see with houseplants. Soils that hold too much moisture and over-watering are the major causes of plant problems.

There is an easy way to determine if a plant needs water. Inserting a finger an inch or so below the surface of the soil will tell if the plant needs water. If the soil is still moist, no water is needed. Water only when the soil around the plant is dry.

Lastly, the plants need to be checked for insects before they're moved into the house. If insects are found, treat them before moving the plants indoors.

Charles Phillips is a retired Columbia County Extension Service agent and operates Hort Consulting. He can be reached at cphillipshort@comcast.net.