Moving Plants Inside for the Winter: What You Need to Know

When pumpkin spiced lattes are the order of the day, it’s time to put garden plants to bed. Or is it? To borrow a phrase from the military, “defense readiness” in the fall garden is all about preventing plant losses, protecting equipment and accessories, and performing general backyard cleanup. If you plan to embark on a change of venue from fresh air to four-walled gardening, these tips will help your plants make a smooth transition from the flowerbed to the windowsill or growroom.

General Preparation

For areas that experience freezing winters, bringing plants indoors in fall may sound like an easy lift and tote operation, but that’s not always true. Putting in the work now can save you problems later.

Check for Pests

A few months in the sun has done wonders for your potted rosemary bush (a chubby survivor from last Christmas), but that verdant new growth may have attracted any number of pests. Before you decide to make it or any other plant a winter resident in your home, an inspection is in order. Check for pests on and under leaves, and look for webbing, eggs, and other telltale signs of habitation. Remove larger insects and destroy any eggs you find.

Even if you don’t spot anything suspicious, treat plants with a mild pesticide like neem oil that is either safe for indoor use or becomes inert a few days after treatment. Read labels carefully, especially if you have young children or pets. Start treating plants a month or so before the first hard frost for your area, and follow up with a few watering sessions to eliminate as much chemical residue as possible. Brisk watering can also discourage any pesky late comers.

If you’re not sure how to identify a reliable target date for the indoor move, check with a USDA Cooperative Extension Office for your area. They can supply you with a reliable frost date estimate. Otherwise, ask one of the hardworking folks at your local nursery. Just in case, it’s also a good idea to keep track of the daily weather report to avoid nasty surprises.

If you have an ailing plant, a pesticide treatment or two may not be enough. A transition from the outdoors will stress any plant, but for a sick plant it’s even more of a shock. Added to that, the small chance a virus or pest may still be present makes the potential for problems too high for the careful gardener. Sacrifice the plant now. The decision protects other specimens, and saves you work, space, and later disappointment.

Perform General Housekeeping

Depending on the variety, trim plants ahead of the move, but avoid the added stress of repotting them. That chore can wait until spring. Check the pruning recommendations for each variety you have in mind for insights about how to trim it safely.

Whether a haircut now is a good idea or not, make sure to remove any dead growth and wipe the sides and bottoms of all your pots to get rid of encrusted dirt and debris. This is also a good time to harvest leaves for drying and saving seeds for next year’s crop.

Read More: How to Harvest and Store Plant Seeds

Clean or Sanitize

Clean any tools you plan to bring indoors too. There’s a difference between cleaning and sanitizing your gardening tools and other gear. If you’ve had a disease-free summer in the garden, you may be able to get away with giving your implements a soak and light scrub with liquid detergent. If you’ve had fungus or other problems, sanitize your tools after cleaning them. This will help ensure you aren’t preserving pathogens along with your plants. Here are a number of sanitizing products are popular with gardeners:

Bleach - One of the least-expensive options is a soak in one-part liquid bleach to nine-parts water for a dwell time of about 30 minutes. Most people have bleach on hand, so this is convenient too. Concentrated or long exposure to bleach can cause reactions in metals like stainless steel and aluminum, and bleach may also react with nylon and some other plastics. If you have high-end tools and testing equipment to worry about, keep that warning in mind. Otherwise, your trowel will probably be okay after a dip in a mild bleach sanitizing solution.

Alcohol - Both isopropyl alcohol and ethanol can be used to sanitize tools and pots. They have a slight advantage over bleach in that a quick wipe down instead of a long soak will do the trick. Prefer a 70 per cent solution or better. Alcohol is flammable, so use caution too.

Hydrogen Peroxide - Hydrogen peroxide (H2O2) is used as a sanitizer in the food service industry and for some hydroponic applications, but the concentrations are higher at 35 per cent compared to the three per cent solution you’ll find at your local drug store. At lower concentrations, hydrogen peroxide is less effective than either bleach or alcohol. You can source concentrated H2O2 through either a local hydroponic supply outlet or food service goods wholesaler.

There are also prepared products like pine cleaners you can use as disinfectants. They are better at killing pathogens than soap and water but are not as effective as sanitizers. Whatever you choose, work outdoors to minimize the risk of inhaling fumes, and avoid mixing ingredients, which could cause unexpected chemical reactions.

For more information on using these products, see Cleanup and Sanitation.

Evaluate Your Indoor Space

Once you identify your “commuter” plants, find a compatible place for them indoors for the duration. Plants that go dormant during winter need very little attention beyond moving them to a cool, dark, and dry location, so we’ll move on to plants that will need regular care over the winter months.

These will probably be the bulk of your collection, and they will require adequate light, stable temperatures, and increased humidity.

Matching plants with the best indoor environment you have available is the key to helping them acclimate successfully. There are some important things to consider:

Light - You know light is essential to a plant’s survival, so it’s probably no surprise that adequate illumination tops our list of indoor growing essentials. Most plants need at least six hours of light a day. Unobstructed sunlight reaching plants should be bright enough to cast a shadow on the floor when you interpose your hand, which, in winter, can be a tall order if you’re relying solely on natural light.

The days are shorter during winter and the light itself is less intense. All other things being equal, a south-facing window will provide more light than an east-facing window, which, in turn, will provide more light than a north-facing window. You may have to juggle plants around a bit until you find the best situation for them.

For a more accurate take on the light intensity you have to offer going forward, invest in a dedicated light meter. There are also a number of light meter apps on the market that may work with your smartphone or other device.

Many plants will alert you that they need more light. Leaf loss, elongated leaves, color loss, and spindly stems can be signs of light deprivation. Plants that have uneven growth (more on the sunny side) or lean toward the light are trying to adapt to less light than they’re used to or need.

If you discover you don’t have enough natural light to sustain specific plants, even after moving them closer to a window, try adding reflective materials like Mylar or aluminum foil to augment the available illumination. If there are still shortfalls, install LEDs or other plant lighting products. Many grow lights on the market today are less expensive and more energy efficient than they were even a few years ago, so consider this potential resource seriously.

Temperature - An acceptable temperature range for an indoor plant will vary by species but generally falls between 65-78°F. This is pretty handy, as the same range is considered comfortable for humans. Indoor cold spots can be sneaky, though, and deadly to plants, so be on the lookout for them.

Temperatures can vary widely near windows, depending on the exposure, the type of window involved (single, double, or triple pane), and the presence or absence of protections like trees or shrubs outside and shades or drapes inside. The safest approach is to keep plants at least eight inches away from windowpanes.

Use a portable thermometer to track temperatures during cold snaps, and close drapes or blinds on cold nights. Avoid placing plants where they will be hit with blasts of arctic air when exterior doors open and close.

If you have a dedicated growroom in your basement or a grow area in your garage, keep plants out of direct contact with concrete flooring. Either elevate them or cover the floor with indoor/outdoor carpeting. For additional warmth, you can also employ plant heating mats. If the insulation in these areas is skimpy, position plants farther away from exterior walls than you would otherwise.

Just as cold is the enemy, hot, dry air can damage or kill plants, too. Choose locations away from heat registers and heat generating appliances.

Moisture and Humidity - The humidity in an average home in winter hovers around 30 per cent or less. Many plants require twice that or more. The old-fashioned solution is to add water to a pebble-filled dish positioned under each plant pot.

As the water evaporates, it contributes humidity to the air. Keeping a number of similarly outfitted plants together in one area creates an indoor microclimate that is somewhat more humid and stable than maintaining plants individually.

Misting equipment or a conventional humidifier will also help increase ambient humidity. If you plan to use grow lights instead of relying on natural light, maintaining plants in a grow tent or other enclosure can help stabilize humidity levels as well. When humidity levels are too low, brown leaf tips may start to appear on otherwise healthy plants. It’s a classic indicator.

Air circulation - While planning your light and temperature control strategy, don’t forget plants need good airflow. Good air circulation helps plants with photosynthesis, reduces the amount of dust on leaves, and discourages pests. It can also reduce problems with mold and mildew.

If you rely heavily on grow lights, good air flow also helps reduce potential heat problems. Invest in a fan, ideally an oscillating fan, for each large group of plants you maintain. If you have a few small plant groupings near a window, a couple of solar-powered fans can be useful and convenient additions.

Bringing Plants Indoors in Fall

The process of bringing plants indoors in fall mirrors the process of adapting seedlings to the outdoors in spring. Plants expect their accommodations to be permanent, and moving them around can be a shock that requires some adjustment.

Once you’ve identified and treated the plants you want to relocate, start getting them used to lower light conditions by moving them to a shadier garden location a week to 10 days before the move. This might be under an awning, a tree, or near the shady side of a fence or wall.

If you only have a few plants to deal with and they aren’t large, consider leaving them outdoors during the day and bringing them indoors at night for a few days before you place them in a permanent location inside. These gradual changes will lessen the stress of the move.

If a plant is too unwieldy, large, or messy to move indoors, this is a good time to take cuttings. Water plants thoroughly before moving day, and save your back by spreading the project over a couple of afternoons. It also helps to put a plastic tarp down to catch any drips or loose grit. If it will fit through the door, use your trusty wheelbarrow or utility cart to move smaller plants en masse.

Oh, and if you have a large, heavy pot to deal with, and stairs aren’t an issue, consider investing in a rolling stand for it.

Too Big to Move? Sheltering in Place

Move potted plants you plan to leave outdoors to a protected location and sink their pots into the soil. Finish off with a three-inch layer of mulch. Soil is a great insulator that will protect plant roots where a completely exposed pot will freeze, killing the roots inside.

Even if a plant is a digit outside its preferred plant hardiness zone, this strategy may be worth the risk, especially if space is tight indoors. With any luck, the plant will survive the winter and be waiting to welcome you back to the garden come spring.

Every plant you save now will be one less specimen to replace next year, so think of the move as a mission of mercy and a cost-saving project all rolled into one. Once you get good at bringing plants indoors in fall, you’ll probably be more tempted to cultivate varieties outside your comfort zone, and outside your plant hardiness zone, too. Ah, gardening… so many plants, so little time!

Read More: The Best Temperatures for an Indoor Grow Room