When to Bring Plants Inside for Winter: The 50°F Rule and a Week-by-Week Plan

The short answer: bring tropical houseplants and tender potted plants inside when night-time temperatures start dropping into the low 50s °F (about 10 °C), and get them in before nights fall below about 45 °F (7 °C). Don't wait for the first frost warning. Many houseplants are tropical, and Iowa State University Extension notes that most of them start to show damage in the mid-to-lower 40s °F, well above freezing (Iowa State Extension).

It also helps to start a week or so before that, because plants do better if you ease them indoors gradually and check them for pests on the way. Below is the temperature rule, what to do before the move, and a simple set of reminders so the job doesn't get left until the cold night when it's already too late.

The temperature rule: watch the night-time low

The number that matters is the overnight low, not the daytime high. A warm afternoon doesn't help a tropical plant if the temperature drops sharply after dark.

The main guidance from US extension services and gardening references is consistent:

Source	When to bring plants in
Iowa State University Extension	When night temperatures "dip consistently into 50s°F"
University of Illinois Extension	"When temperatures drop below 55°F"
The Old Farmer's Almanac	Start as nights reach about 50 °F (10 °C); have plants in "before nighttime temperatures dip below 45°F (7°C)"
Royal Horticultural Society (UK)	Be ready to move tender plants under cover when temperatures drop below 12 to 15 °C, possibly from September

Sources: Iowa State, Illinois Extension, Almanac.com, RHS.

In practice: once the forecast shows nights in the low 50s °F (around 10 °C), start the process. If a night below 45 °F is forecast, bring the tropical plants in that evening, ready or not. The Almanac notes that most tropical plants suffer damage below 40 °F.

Why the first frost date is too late

Frost dates are about 32 °F. The Farmers' Almanac defines its frost dates as light frost, "generally associated with temperatures around 29°F to 32°F," based on 1991 to 2020 climate data (Farmers' Almanac). Your houseplants need to be inside well before that.

The first frost date is still useful as a backstop: if it's coming up and your plants are still outside, you're late. To find yours, the Old Farmer's Almanac has a frost dates tool for the US and Canada. You enter a ZIP or postal code and it gives an average date from the nearest weather station. It's based on a 30% probability, so frost can still arrive before that date.

Roughly, from the Farmers' Almanac 2026 ranges:

• Mid-September to early October: Northern Plains, Upper Midwest, northern New England.
• Early to late October: much of the Midwest, Great Lakes and interior Northeast.
• Late October to mid-November: lower Midwest, Mid-Atlantic, central South.
• Mid-November to early December: Deep South and Gulf Coast.

In the UK, the RHS says plants may need moving from September, though in milder parts of southern England it may not be necessary until well into November (RHS).

Before the move: the pest check

The biggest risk of bringing plants inside isn't the move itself. It's the insects that come in with them and spread to the plants that stayed indoors all summer. Illinois Extension lists aphids, whiteflies, scale and spider mites as the common hitchhikers (Illinois Extension). The RHS adds vine weevil in the soil and rust on pelargoniums and fuchsias (RHS).

Before each plant comes in:

1. Rinse the leaves outside with a strong spray of water, including the undersides. Iowa State advises letting the foliage dry completely before bringing the plant in.
2. Check the pot all over, especially under the rim, for bugs, slugs, cocoons and egg masses (Almanac.com).
3. Flush the pot with water to drive out soil insects such as earwigs and ants (Illinois Extension).
4. Treat what you find. Illinois Extension notes that insecticidal soap can be used on soft-bodied insects. If a plant is badly infested, it may not be worth bringing in.

Ease them in over about a week

A plant that's been in full sun all summer will drop leaves if it suddenly moves to a living room. Illinois Extension suggests moving plants to progressively shadier spots outside over about a week before they come in. Some leaf drop after the move is still normal, and Iowa State notes new growth will replace it.

Once inside:

• Light: bright, indirect light, or a south- or west-facing window.
• Watering: less often than outdoors. Illinois Extension suggests pushing a finger into the soil to the second knuckle and only watering if it's dry there.
• Feeding: Iowa State advises stopping fertilizer in fall and winter, since the plants aren't actively growing.

Keep them apart for 3 to 4 weeks

Even after a careful check, pests can hide. Iowa State recommends keeping returning plants separate from your other houseplants for 3 to 4 weeks and watching for scale, mealybugs and aphids. The Almanac notes that spider mites have a 7 to 10 day life cycle, so a weekly check (and weekly spraying if you find them) is what stops them.

The reminders worth setting

This is a job with several steps spread over about a month, and it depends on weather you won't be watching every day. A reminder can't read the forecast for you, but it can make sure you look at the right time. Here's a simple set, using an average first frost date of 25 October as the example:

1. About 3 to 4 weeks before your first frost date (late September or early October): "Check the 10-day forecast. If nights are in the low 50s, start moving houseplants into the shade."
2. About a week later: "Pest check: rinse leaves, check under pot rims, flush the pots. Let them dry."
3. Move-in day: "Bring the houseplants in tonight. South or west window, away from the other plants."
4. Weekly for 4 weeks after: "Check the plants by the window for spider mites, scale and mealybugs."
5. 4 weeks after move-in: "Quarantine's over. Move them in with the rest if they're clean."

For sudden cold snaps: if the forecast shows a night below 45 °F (7 °C) before you're ready, set a one-off reminder for that evening and bring them in, even if the pest check has to happen inside the garage or bathroom.

Let your phone ring for it

App notifications are easy to swipe away, especially for something like "check the forecast" that never feels urgent until the night it is.

ReminderIt calls your phone at the time you choose and reads your reminder out loud. If you miss the call, the reminder comes to you on WhatsApp. You can set it up just by messaging ReminderIt on WhatsApp, for example:

• "Call me tomorrow at 6 pm: check the forecast and start moving the houseplants into the shade."
• "Call me every Saturday at 10 am: check the plants by the window for spider mites." You can cancel it with a message once the four weeks are up.
• "Call me tonight at 7 pm: frost warning, bring the patio pots in."

An early-evening call works well for the move-in reminder: there's still some light, and it's before the temperature drops overnight. For the rest of the year, see our guides to watering reminders for your plants and seasonal garden tasks. If the same cold night also threatens your plumbing, there's a frozen pipes checklist too.

There's a 7-day free trial with 7 reminder calls (3 if your number is in a country where calls cost more to place, such as the UK). After that, it's one plan at $7 a month (₹299 in India), with 70 calls a month for your plants and everything else you need to remember.

The short answer

Bring tropical houseplants and tender potted plants inside once night-time lows reach the low 50s °F (about 10 °C), and get them in before nights drop below 45 °F (7 °C). Don't wait for the first frost. Start a week early: move the plants into the shade, rinse them, check the pots for pests, and then keep them apart from your other houseplants for 3 to 4 weeks. Set a reminder to check the forecast a few weeks before your average first frost date so the move happens on your schedule, not the weather's.

Sources: Iowa State University Extension and Outreach, How and when do I bring my houseplants back indoors before winter?; University of Illinois Extension, Bring houseplants indoors before the first frost; The Old Farmer's Almanac, How to Bring Outdoor Plants Indoors for Winter and Frost Dates; Farmers' Almanac, First Frost Dates 2026; Royal Horticultural Society, Overwintering plants in conservatories.