Winterizing Pond Plants

An easy guide for preparing pond plants for winter so they come back year after year.

Winter does not send every pond plant the same packing list. Hardy water lilies may simply need a deeper spot, bog plants often stay right where they are, and tropical favorites may need a winter vacation indoors. The trick is knowing which plant you have and protecting the part that needs to survive.

What defines a hard freeze? A hard freeze occurs when the air temperature falls to 28°F or lower for an extended period. That can kill many exposed tender plants, but it is not the deadline to use for bringing tropical pond plants indoors. Move cold-sensitive plants before your first frost or when temperatures reach the minimum recommended for that plant. Papyrus, for example, can be damaged when temperatures approach 40°F, well before a hard freeze arrives.

You have probably heard the term “ice line,” but what is it? Water is densest at about 39°F, so that water settles toward the bottom as a pond cools. Colder water remains closer to the surface, where it can freeze. The ice line, also called the freeze line, is the deepest level at which ice is expected to form in your pond.

That depth is not the same everywhere. Climate, pond depth, exposure, circulation, snow cover, and the severity of a particular winter all play a part. In a mild climate, placing a hardy water lily 18 to 24 inches below the surface may be enough. In colder areas, its rhizome may need to sit 30 inches deep or more. The goal is to keep the plant’s crown, rhizome, or tuber below the deepest expected ice without placing it deeper than that species can tolerate.

Not sure about your USDA Plant Hardiness Zone or when frost typically arrives? Find your zone and average frost dates here to check both. Your zone describes average annual extreme minimum winter temperatures; your local frost dates are a separate guide for timing fall chores.

Below is a quick-look guide to some of the most common pond plants and how to protect them before winter.

Plant names matter here. Hardiness and winter care can vary between species and cultivars sold under similar common names, so check the botanical name on your plant label whenever possible.

Quick Winter Checklist

Action	What to Do
✂️ Trim	Remove dead, yellowing, or decaying foliage so it does not add excess organic matter to the pond over winter.
⬇️ Protect or Lower	Move hardy deep-water plants below the deepest expected ice. Keep marginal and bog plants at a depth that suits the species. Many should not be deeply submerged.
🏠 Keep Growing Indoors	Move tropical plants that remain actively growing to a bright, frost-free indoor setup with the right amount of water.
📦 Store Dormant	Lift bulbs, tubers, or rhizomes when that is the recommended winter method for the plant.
♻️ Remove Responsibly	Remove tender floating plants before they freeze and decay. Never release pond plants into natural waterways, ditches, or storm drains.

🌿 Keep in the Pond

Hardy plants that can overwinter outdoors where they are suited to the local climate

“Keep in the pond” does not mean “send everything to the bottom.” Deep-water plants, marginals, and bog plants have different needs. Use the table below as a starting point, then adjust for your exact species, local hardiness zone, and expected ice depth.

Plant	Winter Care
Acorus (Sweet Flag)	✂️ Remove dead foliage. Keep at its normal marginal depth if it is hardy in your area; do not deeply submerge it by default.
Aquatic Mint	✂️ Trim dead growth and leave at its normal wet-edge or shallow-marginal depth.
Arrow Arum	✂️ Remove dead foliage and protect the root zone from freezing solid while maintaining an appropriate shallow-water depth.
Arrowhead	✂️ Trim after dieback and keep the tubers from freezing solid.
Bog Bean	✂️ Remove dead growth and leave at its normal shallow-water depth.
Cardinal Flower	✂️ Trim dead stems. Keep the crown in saturated soil at the bog edge and out of standing water over winter; do not lower it into deep water.
Corkscrew Rush	✂️ Remove dead growth. Leave at its normal marginal depth or lower slightly only if needed and suitable for the plant.
Creeping Jenny	✂️ Trim as needed and leave at the bog edge or in very shallow water; do not lower it into deep water.
Dwarf Bamboo (Dulichium arundinaceum)	✂️ This is a marginal sedge, not a true bamboo. Trim dead foliage and keep it at its normal shallow depth.
Dwarf Cattail	✂️ Trim dead foliage and leave at its normal marginal depth; lower slightly only if needed to protect the root zone.
Golden Club	✂️ Remove dead foliage and protect the crown and rhizome while maintaining the plant’s normal water depth.
Graceful Cattail (Typha laxmannii)	✂️ Trim after dieback and leave at its normal marginal depth; lower slightly if appropriate.
Hardy Water Iris	✂️ Trim dead foliage and keep at its normal marginal depth. Check the species or cultivar because hardiness varies.
Hardy Water Lily	✂️ Remove dead pads and stems. Lower the container so the crown and rhizome remain below the deepest expected ice.
Hornwort	✂️ Remove decaying material. Healthy hornwort can remain in the pond and will usually settle deeper as the water cools.
Horsetail Rush	✂️ Remove dead growth and keep at its normal marginal depth; lower slightly only if needed.
Chameleon Plant	✂️ Trim dead growth and leave at the wet edge or bog margin where it is hardy. Keep it contained because it spreads aggressively by rhizomes.
Lizard’s Tail	✂️ Trim after dieback and leave at its normal shallow-marginal depth.
Lotus	✂️ Remove dead foliage. Position the container so the tuber remains below the deepest expected ice, or move it to a frost-free location if the pond is too shallow.
Marsh Marigold	✂️ Remove dead foliage and leave at the bog edge or its normal shallow depth; do not deeply submerge it.
Parrot’s Feather	✂️ Remove dead growth. Where possession is legal, keep hardy growth below freezing water or maintain it in a controlled indoor setup. Never release it; this plant is invasive and restricted in many areas.
Pickerel Rush	✂️ Trim dead foliage and leave at its normal marginal depth; lower slightly if appropriate for the plant and pond.
Soft Rush	✂️ Remove dead growth and leave at its normal marginal depth; lower slightly only if needed.
Water Canna (Thalia dealbata)	✂️ Trim after dieback. Where it is winter-hardy, move the crown to about 18 to 24 inches of water for winter; otherwise move the container to a bright, frost-free location.
Water Celery	✂️ Trim dead growth and keep at its normal shallow depth where hardy. Contain all pieces, because viable fragments may root and spread.
Dwarf Water Clover (Marsilea minima)	✂️ Remove dead growth and protect the roots from freezing solid where hardy. Keep it at an appropriate shallow or submerged depth.
Zebra Rush	✂️ Remove dead foliage and leave at its normal marginal depth; lower slightly only if needed.

🏠 Bring Indoors or Store Dormant

Tropical and cold-sensitive plants that need protection before frost or chilling temperatures arrive

Some plants want a bright indoor pond; others are perfectly happy sleeping the winter away as a bulb, tuber, or rhizome. Follow the method for your exact species or cultivar instead of placing every plant in the same cool, dim room.

Plant	Winter Care
Tropical Water Lily	🏠 Keep actively growing in an indoor tub or aquarium with strong light and water around 70°F or warmer, or lift and store a mature tuber using the method recommended for the cultivar.
Calla Lily (Zantedeschia)	📦 Where it is not winter-hardy, lift after dieback, cure, and store the rhizome in a cool, dry, frost-free place.
Canna	📦 After frost kills the top growth, but before the rhizome freezes, lift it, cure it briefly, and store it in a cool, frost-free place.
Colocasia	🏠 Bring the potted plant indoors before frost and keep it growing, or lift and store the tuber dormant. Hardiness varies considerably by cultivar, so use the rating for the exact plant rather than a blanket zone rule.
Dwarf Papyrus	🏠 Bring inside before temperatures approach 40°F. Provide bright light, about 60 to 65°F or warmer, and keep the container standing in water.
Dwarf Umbrella Palm	🏠 Keep bright and frost-free, with the roots continuously moist or the pot standing in shallow water.
Fiber Optics Rush (Isolepis cernua, also sold as Scirpus cernuus)	🏠 This is a tender perennial, generally hardy only in Zones 8–11. In colder climates, bring it indoors before freezing weather and place the pot in a shallow tray of water near a sunny window.
Papyrus (Paper Plant)	🏠 Bring inside before temperatures approach 40°F. Give it bright light, warmth, and consistently wet roots; do not let it dry out.
Pink Fairy Lily / Zephyr Lily (Zephyranthes rosea)	📦 Below its hardiness range, lift and store the bulbs in a cool, dry, frost-free place without allowing them to become bone-dry.
Spider Lily (Hymenocallis liriosme)	📦 Where it is not hardy, lift before freezing weather and store the bulb frost-free, or keep the container growing indoors according to the plant’s needs.
Star Grass / White-topped Sedge (Rhynchospora colorata, also sold as Dichromena colorata)	🏠 This plant is generally hardy in Zones 7–10. In colder climates, move it to a bright, moist, frost-free location before freezing weather.
Taro	🏠 Bring the potted plant indoors before frost and keep it growing, or lift and store the tuber dormant. Check the exact species and cultivar because cold tolerance varies.
Thalia	🏠 Check the botanical name before choosing a winter method. Thalia dealbata is the hardy Water Canna listed above; tropical Thalia geniculata should be moved to a warm, bright, frost-free location before frost and kept wet or consistently moist.
Umbrella Palm	🏠 Keep bright and frost-free, with continuously moist roots or the pot standing in shallow water.
Water Poppy	🏠 Where it is not hardy, treat it as an annual or maintain it in a warm indoor aquatic container with strong light and its roots submerged. Merely storing it in moist soil is not enough.
White Snowflake (Nymphoides indica)	🏠 Where it is not hardy, treat it as an annual or keep it in a warm indoor aquatic container with strong light and submerged roots.

Caring for Plants Overwintered Indoors

Bringing a plant inside is not a “set it and forget it” move, but it also does not mean every plant needs a tropical spa day. First decide whether the plant will remain actively growing or be stored dormant.

Keep-Growing Plants

Factor	Guidance
Light	Use a bright window or grow light. Tropical water lilies, water poppy, and white snowflake need especially strong light to remain healthy.
Temperature	Match the plant rather than using one setting for everything. Papyrus and umbrella palms prefer warm, frost-free conditions; actively growing tropical water lilies generally need water warmer than 68°F.
Water	Keep true aquatic plants in an appropriate indoor tub or aquarium. Papyrus and umbrella palms need continuously wet roots and can stand in shallow water. Do not reduce all plants to merely "moist soil."

Dormant Plants

Factor	Guidance
Timing	Lift tender bulbs, tubers, and rhizomes before the underground parts freeze. Some, such as canna, can wait until a light frost has killed the top growth.
Storage	Keep them frost-free and follow the species-specific recommendations for curing, temperature, and moisture. Too much moisture encourages rot; too little can shrivel some bulbs and tubers.
Checkups	Inspect stored plants occasionally and discard material that becomes soft, moldy, or badly rotted.

Before Anything Comes Indoors

Rinse away pond debris and inspect leaves, pots, and roots for insects, egg masses, snails, and unwanted plant fragments. Keep pond water and hitchhikers out of household aquariums unless you intentionally quarantine them first.

♻️ Remove and Dispose Responsibly

Tender floating plants are generally treated as annuals where winter temperatures freeze the pond.

Plant	Winter Care
Water Hyacinth	♻️ Remove before freezing weather so it does not decay in the pond. Never release it outdoors. Follow local rules; if it is restricted or may remain viable, seal it in a bag and place it in the trash.
Water Lettuce	♻️ Remove before freezing weather so it does not decay in the pond. Never release it outdoors. Follow local rules; if it is restricted or may remain viable, seal it in a bag and place it in the trash.

Compost pond plants only when local regulations allow it and the material is completely dead and unable to spread. Do not place living plants or viable pieces in natural water, drainage ditches, storm drains, or flood-prone compost piles.

Important

Winter care depends on the exact species or cultivar, your USDA Plant Hardiness Zone, local frost timing, pond depth, and the deepest ice your pond is likely to develop. Protect hardy crowns, rhizomes, and tubers from freezing solid, but do not deeply submerge bog or marginal plants that are not adapted to deep water. When a common name could refer to more than one plant, check the botanical name before choosing a winter method.