Overwintering Container Plants

Why overwintering container plants makes sense

Every tropical or frost-sensitive container plant you successfully overwinter is money saved in spring. A mature mandevilla vine costs $25-50 to replace; a large canna clump costs $20-30; a well-established banana plant, $40+. One successful overwintering season recovers the time investment.

Beyond cost, overwintered plants start the next season ahead of newly purchased ones. A mandevilla that overwinters and begins spring at 3-4 feet tall will flower by June. A new plant purchased in May might not bloom until August.

There are three main overwintering strategies:

1. Dormant storage (best for tropicals): bring the plant inside, let it go dormant in a cool location, provide minimal care
2. Active growing (indoors as a houseplant): move the container to a bright window and maintain regular watering and care
3. Root protection only (for marginally hardy perennials): leave the container outside but protect the root zone from deep freezing

The right strategy depends on the plant. This guide covers all three approaches with plant-specific guidance.

When to bring plants inside

Move frost-sensitive container plants indoors before the first frost warning. But do not wait until frost is forecast — many tropical plants show chilling damage at temperatures below 50°F, before any frost occurs.

Timing by zone:

Inspecting for pests before bringing plants inside

This step is critical and often skipped. Outdoor plants host insects that will rapidly colonize your houseplants once brought inside a warm environment.

Common hitchhikers:

• Spider mites — look for fine webbing on undersides of leaves; thrive in dry indoor air
• Whiteflies — tiny white moths that fly up when the plant is disturbed
• Scale insects — look like brown bumps on stems; easy to miss
• Mealybugs — white cottony masses in leaf axils and on stems
• Fungus gnat larvae — in the soil; adults are small gray flies

Inspection routine before bringing plants inside:

1. Move the plant to a bright area and examine undersides of leaves with a 10x hand lens.
2. Check stem crotches and leaf axils for mealybug and scale.
3. Check the soil surface for fungus gnat larvae.
4. If you find any pests, treat with insecticidal soap (spray all leaf surfaces) before bringing the plant inside.
5. Quarantine newly moved-inside plants for 2 weeks — keep them away from other houseplants until you’re confident no pests are present.

Strategy 1: Dormant storage for tropical perennials

Many tropicals can go dormant (lose leaves, stop growing) and survive winter in a cool, dark location. This is the easiest and most reliable method for the following plants:

Canna

Canna rhizomes are winter-hardy to Zone 8. In Zones 3-7, dig them after the first frost blackens the foliage:

1. Cut stems to 6 inches after foliage dies.
2. Dig the rhizome clump carefully.
3. Allow rhizomes to dry for 24 hours in a dry, shaded location.
4. Shake off excess soil; do not wash.
5. Store in boxes of barely moist peat moss or coco coir at 40-55°F.
6. Check monthly — rhizomes should be firm, not shriveled or rotted.
7. In April, divide and pot rhizomes 4-6 weeks before last frost to give them a head start indoors.

Mandevilla

Mandevilla overwinters beautifully as a dormant bare-root plant:

1. In late September, cut stems to 12-18 inches.
2. Knock the root ball out of the pot.
3. Store bare-root in a paper bag (not plastic — needs air circulation) at 40-55°F.
4. Provide no water until late winter.
5. In February or March, pot the root ball back up, begin watering, and move to a south-facing window.
6. Move outdoors after the last frost.

For more detailed mandevilla growing information, see our mandevilla vine care guide.

Elephant ear (Colocasia, Alocasia)

Elephant ears need frost-free storage. Treat the same as cannas: dig after frost, dry briefly, store in barely moist peat at 50-60°F. These are more cold-sensitive than cannas — do not let them experience temperatures below 40°F.

Caladium bulbs

Similar storage to canna rhizomes. Dig after frost; dry for 1 week; store in dry peat at 55-65°F. Caladiums are more rot-prone than cannas — check monthly and remove any soft bulbs.

Strategy 2: Active overwintering as a houseplant

Some plants do not go easily dormant and need light and minimal water through winter. These require a bright, cool location — typically a south or west-facing window.

Geraniums (Pelargonium)

Three methods work:

Active growing: Keep the potted plant in a cool, bright window (55-65°F). Water when the top inch of soil dries out. Expect some leaf drop. Prune back to 6 inches in February to encourage fresh growth before moving outside in spring.

Bare-root storage: Dig the plant, shake off soil, hang upside down in a cool (40-50°F), frost-free basement or garage. The roots slowly dehydrate over winter. In February, cut stems back and pot up in fresh potting mix. Water and grow on a sunny windowsill. Emergence rate: 70-80% — not every plant survives this method.

Brown bag storage: Place entire plants in paper bags loosely, stems trimmed to 6 inches, in a cool dark location. This is similar to bare-root but slightly more reliable.

Hibiscus (tropical)

Tropical hibiscus needs bright light through winter — it does not go dormant well. Move to your brightest window (south-facing preferred). Reduce watering to once per week. Expect leaf drop of 50% or more — this is normal. Fertilize lightly in February when new growth resumes.

If you do not have a bright indoor location, tropical hibiscus is one of the harder plants to overwinter successfully. Many gardeners in Zones 5-6 simply replace it each spring.

Bougainvillea

Bougainvillea can be coaxed to go semi-dormant in a cool, dim location (45-55°F) with minimal water and no fertilizer. It drops most of its leaves. This semi-dormancy method works better than trying to grow it actively indoors during the short winter days. Resume regular watering in March; move outdoors in May.

Strategy 3: Root protection for marginally hardy plants

Perennials that are borderline hardy for your zone (one zone less cold than you experience) can often survive winter in containers if the root zone is protected from deep freezing.

How to protect roots in containers:

1. Move the container to a sheltered location: against a south-facing wall, inside an unheated garage or shed, or inside a cold frame.
2. Wrap the pot in 4-6 layers of burlap and secure with twine.
3. Pack straw bales around the outside of the pot for additional insulation.
4. Do not bring the pot into a heated space — these plants need cool dormancy, not warmth.

Plants suited to this method:

• Lantana (in Zone 6): roots survive winter in a protected container; cut back hard in early spring
• Hardy banana (Musa basjoo): roots are cold-tolerant; protect the crown with 12 inches of mulch
• Rosemary (in Zones 5-6): often not reliably winter-hardy; a sheltered container location adds one zone of protection
• Lavender in Zone 5: similar to rosemary; improved drainage and a sheltered location increases survival

In-ground dormant storage for bulbs and rhizomes

Many bulbs grown in containers can also be dug and stored in a cool basement without soil:

Spring reintroduction

Bring overwintered plants back to active growth gradually:

1. Start 4-6 weeks before your last frost date.
2. Move dormant plants from storage to a warmer location (60-65°F) with bright light.
3. Resume watering slowly — once per week until new growth appears.
4. Once actively growing, begin dilute fertilizer.
5. Move outdoors only after all danger of frost has passed.

Harden off plants that have been indoors all winter before full outdoor exposure. Even shade-tolerant plants need 7-10 days of gradual outdoor exposure (starting with 1-2 hours per day and increasing) before leaving them out full-time.

Fall container garden timing: the full sequence

1. 6 weeks before first frost: inspect plants for pests; treat any infestations before bringing plants inside
2. 4-6 weeks before first frost: move most tender tropicals inside as nights approach 50°F
3. First light frost: dig cannas, dahlias, elephant ears; store per above
4. After hard freeze: final cleanup of containers that stayed outside
5. November onwards: monthly check on stored roots; remove any rotted sections

For more on the full fall garden process, see our fall garden prep guide. Our container gardening guide covers selecting containers and potting mixes that make both summer growing and winter storage easier.

Quick reference: overwintering common container plants

University of Illinois Extension offers a detailed guide on overwintering tender perennials and tropical container plants with photographs of each storage method: extension.illinois.edu.