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Many indoor plants can be damaged at temperatures below 45-50 degrees without showing signs of injury at first. Tender plants should be brought back indoors at the end of the summer before overnight lows are too cold.

Courtesy Meredith Seaver, USU Extension

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Plants can be moved closer to a window during the winter if they need more light, but keep in mind that the air near windows is usually much colder than the room in general.

Courtesy Meredith Seaver, USU Extension

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Cooler winter temperatures and lower light levels make it easier for indoor plants to suffer the effects of wet soils from overwatering. It's important to use the best watering practices. For example, water deeply, but never leave plant pots sitting in the water that drains from the pot.

Courtesy Meredith Seaver, USU Extension

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My pothos leaves started turning yellow a couple of weeks after I brought it in for the winter. Now the leaves are dropping off if I brush against them. Could it be because of the sudden change from cold nights outside to being in my warm house? What should I do for it?

A sudden change in conditions can be stressful for a houseplant; some will even struggle after being moved from one side of a room to another. You don’t say when you brought your pothos inside, but my best guess is that the plant was outside too late in the season and is suffering from cold injury.

Many tender plants don’t need to actually freeze to be damaged. Cold injury can occur at temperatures as warm as 45-50 degrees. Most houseplants are tropical or subtropical plants and are very tender. Wet weather combined with cold temperatures can worsen cold injury.

The damage from cold injury can’t be undone, but there are some things you can do to encourage your pothos to bounce back:

• Trim back any severely wilting vines or vines left bare by dropped leaves.
• Let soil in the container dry somewhat between deep waterings.
• Keep your pothos in a room that says between 65 and 80 degrees.
• Don’t place your plant near drafts, heat vents, fireplaces, wood stoves or chilly windows.
• Be patient. With time and good care, your pothos may recover.

Houseplant care for winter

While we’re on the topic of indoor plants, let’s review some basic plant care information for the coldest months of the year.

Wintertime brings some changes that can challenge even the healthiest indoor plants. The natural light levels in your home change, the indoor air will be drier, the temperature in your home may be lower but the temperature near your windows will be lower.

These changes all affect the way your houseplants grow during the winter but that doesn’t mean you can’t manage those changes to give your indoor greenery a good winter.

Good lighting is important to all plants. Some need bright light and others need lower levels, but all plants need the right light for them. There are some things you can do to help your plants deal with the change in lighting:

• Gently dust off smooth leaves and blow off downy leaves so that your plants can make use of all the light they get.
• Move your plant closer to a window without putting it in a chillier setting.
• For plants near a window or strong one-sided lighting, rotate the plant one-quarter turn every week to prevent the plant from leaning.
• Increase the lighting in the room, either leaving lights on for longer during the day and evening or by adding additional lights near the plants.

Indoor temperatures are often a little cooler during the winter, but there are some homes where warmer temperatures are the choice. Either way, it will affect your plants’ needs and how they do during the winter. Temperatures a few degrees cooler mean slower growth for most plants. If your home is a few degrees warmer, it will encourage your plant to grow a little faster, but without the brighter lighting needed for the healthiest growth.

Watering routines should be changed for the winter. With lower light and shorter days, your houseplants will naturally grow more slowly and use water more slowly. You’ll still want to water just as deeply as you usually do, but it’s important that you do that less often. Watering before it’s needed will keep the soil wet, encouraging root rot diseases. Your plant will tell you when it’s thirsty — the top of the soil will be dry, and the pot will feel a little lightweight.

It’s very difficult to make up for the drier winter air. Smaller plants can be set on pebble trays of water, and for larger plants the most important thing you can do is protect them from the drying air of furnace vents.

What about fertilizer for your indoor plants during the winter? This is one houseplant task you can skip for a few months. Fertilizer will push new green growth. But wintertime, with its lower light levels, should be a resting time for plants, not a growing time.