Bury it, group it or garage it: a winter plan for every pot

It's a common spring discovery: a hosta in the bed comes back fine, and the same hosta in a pot by the door doesn't. Iowa State Extension explains why. The roots of a plant are far less cold hardy than its stems and buds, and in a pot above ground the mix can fall into the single digits, cold enough to damage or kill the roots.

Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.

Illinois Extension puts it the same way: a pot holds only a little mix, and that mix gets much colder than soil in the ground. In a bed, each root has deep earth all around it. In a pot, it has a thin wall and open air on every side.

Source: Illinois Extension, overwintering potted plants, checked October 6, 2026.

• 20 to 45°Fthe cold-storage range for an unheated garage or shedIowa State Extension, overwintering unplanted trees, shrubs and perennials, October 7, 2026
• 6 to 12 inof loose straw or pine needles over buried potsIowa State Extension, overwintering unplanted trees, shrubs and perennials, October 7, 2026
• 2 to 3 weeksbetween waterings in storage when it's above freezingIowa State Extension, overwintering unplanted trees, shrubs and perennials, October 7, 2026
• 2 zonescolder: how hardy a plant that stays out in its pot should beIllinois Extension, overwintering potted plants, October 6, 2026

You don't need one plan for the whole patio. Sort the pots by what you can lift and how hardy the plant is, then give each pot the plan it fits.

Burying and the garage come from Iowa State and Illinois Extension; grouping and the two-zone rule come from Illinois Extension.

Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026; Illinois Extension, overwintering potted plants, checked October 6, 2026.

1. 1

   Check each tag against your zone

   Look up your zone, then read the plant tag. For a pot that stays outside all winter, Illinois Extension says choose plants that survive two zones colder than where they grow (the two-zones-colder rule explains why). If the tag doesn't reach that far, the pot goes in the ground or the garage.

   Source: Illinois Extension, overwintering potted plants, checked October 6, 2026.

2. 2

   Wait for the first frost

   Iowa State Extension says to bury pots within a few weeks after the first fall frost, once the plants are heading into dormancy.

   Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.

3. 3

   Bury: dig, set, backfill

   Dig a hole in a garden bed, set the pot in, and pack soil around it as if you were planting it. The bed's soil does the insulating.

   Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.

4. 4

   Cover the buried pots

   Once the plants are dormant, spread 6 to 12 inches of straw, pine needles or other loose mulch on top. Iowa State Extension advises against leaves here, because they pack down and can smother the plants.

   Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.

5. 5

   Or group them against a wall

   Cluster the pots on the north or east side of a building, away from strong wind and too much sun, then mulch heavily around them with straw, leaves or wood mulch.

   Source: Illinois Extension, overwintering potted plants, checked October 6, 2026.

6. 6

   Or store them cold, not warm

   Move dormant pots into an unheated garage, shed or cool basement. Iowa State Extension's range is about 20 to 45°F. A heated room sits well above that range.

   Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026; Illinois Extension, overwintering potted plants, checked October 6, 2026.

Dormant doesn't mean dry. Illinois Extension says to water the plants well before winter and check them through the season. For pots in a garage or shed, Iowa State Extension says they may need water as often as every two to three weeks while it's above freezing.

Source: Illinois Extension, overwintering potted plants, checked October 6, 2026; Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.

A simple routine: set a phone reminder for every second weekend from the first frost to spring. When it goes off, push a finger 2 or 3 inches into the mix, the check WSU Extension suggests for containers. Water only if it feels dry, and only when the mix isn't frozen.

Source: WSU Extension, Container Gardening tip sheet 6, checked October 7, 2026.

Iowa State Extension takes the straw off buried pots around mid-March in Iowa. Your own date shifts with your frost dates, so go by the weather where you are, not the calendar. Lift the pots, brush off the soil, and check whether the mix sank. A pot that settled over winter needs a top-up before it goes back on the patio.

Source: Iowa State Extension, overwintering unplanted trees, shrubs and perennials, checked October 7, 2026.