Transplanting Plants Indoors for Winter: How to Bring Your Garden Inside

You spent all summer babying that hibiscus. The geraniums finally look like the picture on the tag. And now the forecast says frost. You could let them go, or you could bring them inside and have a little bit of summer on your windowsill all winter.

Bringing plants indoors is easy if you do it right. Do it wrong, and you'll bring in a few hundred aphids, a family of spiders and a plant that drops every leaf in a week out of pure spite. Here's how to choose which plants to save, when to move them, how to get them in bug-free, and how to keep them alive until spring.

Which Plants Can You Bring Indoors?

Skip: big annuals at the end of their life (petunias, marigolds, zinnias), anything badly infested with bugs, and plants too big to fit near a window. Hardy perennials and shrubs that are meant to go dormant outside should stay outside.

When to Bring Plants Inside

Before night temperatures drop below 50°F. Tropical plants like hibiscus and mandevilla start sulking at around 55°F. Most plants need to come in at least a couple of weeks before your first frost date, not the night of. Look up your area's average first frost date, and plan backward.

Step 1: Debug Everything

This is the step everybody skips, and it's the reason so many people give up on bringing plants inside. Outdoor plants come with passengers: aphids, spider mites, mealybugs, whiteflies, scale and the occasional earwig.

1. Inspect each plant, including the undersides of the leaves, the stems and the soil surface.
2. Hose it off with a strong spray of water, top and bottom.
3. Soak the pot. Set the whole pot in a tub or bucket of lukewarm water for 15 minutes. Anything living in the soil will come up for air, and you can scoop it out.
4. Spray with insecticidal soap if you see any bugs, following the label, and repeat in a week.
5. Quarantine it away from your other houseplants for two weeks. If something hatches, it won't spread.

Step 2: Transplant Garden Plants Into Pots

f the plant is growing in the ground, it needs a pot.

1. Water the plant well the day before you dig.
2. Dig a wide circle around it, keeping as much of the root ball as you can.
3. Choose a pot just a little bigger than the root ball, with drainage holes.
4. Use fresh potting mix, never garden soil. Garden soil packs down hard in a pot, drains badly and brings bugs and diseases inside.
5. Set the plant at the same depth it was growing, fill in around it and water well.

Already in a container? Check the drainage, top off the soil, and repot only if it's badly root-bound.

Step 3: Prune It Back

Trim leggy or overgrown plants by up to a third. A smaller plant is easier to fit by a window and needs less light to stay healthy. Pinch off flowers and seed heads too, so the plant puts its energy into getting settled.

Step 4: Ease Them Inside Slowly

Going straight from full sun to your living room is a shock, and plants respond by dropping leaves. Over a week or two:

1. Move the pots into shade outdoors for a few days.
2. Bring them in at night, and back out during the day if it's warm.
3. Then bring them in for good, to the sunniest spot you have.

Some leaf drop is normal even if you do everything right. The plant is adjusting to less light. New leaves grow in once it settles.

How to Keep Plants Alive Indoors All Winter

• Light: the sunniest window you have, usually south- or west-facing. Turn the pots a quarter turn every week. If you don't have a sunny window, use an LED grow light for 12 to 14 hours a day on a timer.
• Water less. Plants grow slowly in winter and need much less water. Water when the top inch of soil is dry. Overwatering kills more indoor plants than anything else.
• No fertilizer from late fall until spring.
• Temperature: 60°F to 70°F suits most plants. Keep them away from heat vents, radiators and cold, drafty windows. Don't let leaves touch the glass on freezing nights.
• Humidity: furnace air is dry. Group plants together, set them on a tray of pebbles and water, or run a humidifier.
• Watch for bugs all winter. Check the leaves every week or two, and treat at the first sign.

Easier Options: Cuttings and Dormant Storage

Don't have room for big pots? You don't have to bring the whole plant in.

Take Cuttings

Geraniums, coleus, begonias, impatiens, basil and many herbs root easily. Snip a 4- to 6-inch stem just below a leaf node, strip the bottom leaves, and stand it in a glass of water or a small pot of damp potting mix on a bright windowsill. In a few weeks you'll have roots, and a whole new plant that takes up a fraction of the space.

Store Geraniums Dormant

The old-fashioned way: dig up the geraniums, shake the soil off the roots, and hang them upside down in a paper bag in a cool, dry basement or garage (about 45°F to 50°F). In spring, cut them back, pot them up and water. It sounds crazy. It works.

Dig and Store Tender Bulbs

Dahlias, cannas, gladiolus, caladiums and elephant ears won't survive a frozen ground. After the first light frost blackens the leaves, dig them up, let them dry for a few days, and store them in a box of peat moss or wood shavings somewhere cool and dark, around 40°F to 50°F. Replant in spring.

A Quick Word About Pets

Before you line up new plants on the windowsill, check that they're safe for your cat or dog. Some popular overwintering plants, like aloe, jade, begonias and citrus, are toxic to pets, according to the ASPCA. Keep those up high, or out of the room where the pets hang out.

Frequently Asked Questions

When should you bring plants inside for the winter?

Before nighttime temperatures drop below 50°F, and at least a couple of weeks before your area's first frost. Tropical plants should come in when nights reach about 55°F.

How do you get rid of bugs before bringing plants inside?

Hose the plant off, soak the whole pot in a tub of water for 15 minutes, spray with insecticidal soap if you see bugs, and keep the plant away from your other houseplants for two weeks.

Can you use garden soil in pots?

No. Garden soil packs down, drains poorly and brings pests and diseases inside. Use fresh potting mix.

Why is my plant dropping leaves after I brought it inside?

It's adjusting to less light. Some leaf drop is normal for a few weeks. Give it the sunniest spot you have, don't overwater, and new leaves will grow in.

How do you keep geraniums over the winter?

Three ways: grow them as houseplants in a sunny window, take cuttings and root them in water, or dig them up and store them bare-root in a paper bag in a cool basement until spring.

Keep Going

The plants are in and the windowsill looks like July. Keep the garden and the house happy all winter with these related guides:

• 10 Fall Gardening Tips: Put the rest of the garden to bed so it wakes up happy in spring.
• Christmas Plant Care Tips: Poinsettias, amaryllis and Christmas cactus that thrive past the holidays.
• A Year of Flower Bulbs: What to plant, and when, for color all year.
• How to Winterize Your Home: A top-to-bottom checklist before the first storm.
• Living Christmas Tree Care: Keep a potted tree alive indoors, then plant it after the holidays.
• Seasonal Chores for Kids by Age: Planting, raking and putting the garden to bed with the kids' help.
• Gardening Games for Kids: Turn the bug hunt into a game.
• Backyard and Garden Guide: Patios, plants and outdoor living for the whole family.

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