Getting pond plants through winter is mostly about one question asked plant by plant: is this thing hardy in my climate, or is it tropical? Hardy plants want to ride out the cold dormant in the pond at a depth that doesn’t freeze solid, while tropical plants will turn to mush at the first hard frost unless you pull them out and keep them warm and bright indoors. Get the category right and the rest is straightforward; get it wrong and you either rot a hardy crown by lifting it into a warm house or lose an expensive tropical lily to ice. This guide sorts the common pond plants—water lilies, lotus, marginals, floaters, and submerged oxygenators—into hardy and tropical, then walks through exactly what to do with each by type, plus a fall checklist to put the whole pond to bed. Throughout, your USDA zone and the depth of your pond do the heavy lifting in deciding what’s “hardy enough” to leave in place.
Key Takeaways
- First sort every plant into hardy or tropical for your USDA zone—that single decision drives everything else.
- Hardy water lilies, lotus, and hardy marginals overwinter in the pond if their crowns sit below the ice line, usually meaning a pond at least 18–24 inches deep (deeper in cold zones).
- Tropical water lilies, tropical marginals, and tender floaters must be lifted before the first hard frost and kept in a warm, bright spot indoors, or treated as annuals.
- Cut back dying foliage, sink hardy marginals and lilies to the deepest part of the pond, and stop feeding fish as the water cools below about 50°F.
- Keep a hole open in the ice for gas exchange with a floating de-icer or aerator—never smash the ice, which shocks fish.
Step 1: Sort Hardy vs Tropical for Your Zone
Everything starts here. A plant labeled hardy in zone 5 is tropical in the sense that matters if you garden in zone 3, and a plant that’s a reliable perennial in zone 9 may need lifting in zone 6. Find your USDA hardiness zone, then check each plant’s rated range against it. If the plant is hardy to your zone or colder, it can usually stay in the pond. If it’s rated only for zones warmer than yours, treat it as tropical: lift it, bring it in, or accept it as an annual.
The second variable is pond depth. “Overwinters in the pond” really means “overwinters below the ice.” Ice forms from the top down, and as long as a hardy plant’s crown or tuber sits in water that stays liquid beneath the ice, it survives. In milder zones a foot or so of water over the crown is enough; in cold-winter regions you want the crown 24 inches or more down, in the deepest zone of the pond, where the water never freezes solid. A shallow container pond freezes through and cannot overwinter anything in place—those plants must come indoors regardless of hardiness.
Water Lilies
Hardy water lilies
Hardy water lilies (Nymphaea hardy types) are the easy case. As the leaves yellow in fall, trim the foliage and flower stems back to the crown, then lower the basket to the deepest part of the pond—below the ice line, ideally with 18 to 24 inches of water over the crown. The tuber goes dormant, sits out the cold, and pushes new growth in spring as the water warms past about 50°F. Don’t fertilize in fall; resume feeding only when active growth restarts in spring.
Tropical water lilies
Tropical water lilies are the high-maintenance case and are killed by frost. Most gardeners in cold zones treat them as annuals, but you can overwinter them two ways. The simplest is to keep the whole plant growing indoors in a tub or aquarium in a warm, very bright spot (a sunny window or grow light), with the water held around 65–70°F. The more compact method is to lift the plant after the foliage dies back, find the small walnut-sized tuber, clean it, and store it damp in a jar of distilled water or moist sand in a cool (about 50–55°F) dark place, checking occasionally for rot. Pot it up indoors in late winter to get a head start, then move it out once the pond is reliably above 70°F.
Lotus
Lotus (Nelumbo) are hardier than people expect—many are reliable to zone 4 or 5—and overwinter in the pond as long as the tuber never freezes. After frost blackens the leaves, cut the foliage back but leave a few inches of hollow stem above the waterline (cutting below the surface can let water into the tuber and rot it). Sink the container to the deepest, non-freezing part of the pond so the tuber stays in liquid water all winter. In a shallow pond or a tub that freezes solid, lift the container and store it somewhere cold but frost-free—a garage or basement around 35–45°F—keeping the soil damp, never wet, and never letting the tuber dry out or freeze.
Marginal (Bog and Shelf) Plants
Hardy marginals
Hardy marginals—pickerel rush, hardy water iris, marsh marigold, sweet flag, hardy rushes and sedges—mostly overwinter in place. Trim the dying top growth back to a few inches above the crown and, if the marginal shelf is shallow enough to freeze, move the basket down to deeper water below the ice line for winter, returning it to the shelf in spring. Many hardy marginals tolerate a frozen crown briefly, but the safe move in cold zones is to drop them deeper. Leave a little stub of hollow stem on plants like rushes so the crown can still exchange a bit of gas.
Tropical marginals
Tropical marginals—umbrella palm, tropical canna and taro (elephant ear), water poppy in cold zones, tropical iris—won’t survive freezing. Lift them before the first hard frost and either grow them on as houseplants in a bright, warm room with their feet in a saucer of water, or store the tubers/rhizomes (canna, taro) cleaned and packed in barely moist peat or sand in a cool, frost-free spot, the same way you’d store dahlia tubers. Pot them back up in spring after the danger of frost has passed.
Floating Plants
Most popular floaters—water hyacinth and water lettuce—are tropical and frost-tender, and in most climates they’re simply treated as annuals: they die at the first frost and you compost them (where legal; both are invasive in warm regions, so never release them to wild water). If you want to save them, scoop a few healthy plants into a tub of water in a warm, brightly lit indoor spot and keep them growing, though they often sulk and it’s frequently cheaper to rebuy in spring. Hardy floaters like frogbit form winter buds (turions) that sink to the bottom in fall and resurface in spring on their own—leave them be. The hardy fern azolla overwinters in mild zones but dies back in hard freezes.
Submerged Oxygenators
Submerged oxygenating plants split the same way. Hornwort, elodea (Canadian pondweed), and hardy pondweeds are hardy: they go semi-dormant, sink lower in the water, and carry on through winter under the ice—just thin out any excess in fall so dying material doesn’t foul the water, and leave the rest. Tender oxygenators like cabomba are frost-sensitive and may collapse in a cold pond; in cold zones, keep a portion indoors in a lit tank as insurance. As a rule, hardy oxygenators need no special winter care beyond a fall cleanup.
Fall Pond Checklist
Pulling it all together, here’s the order of operations as the season winds down:
- Cut back dying foliage on lilies, lotus, and marginals before it collapses into the water and rots—leaving hollow stem stubs on lotus and rushes above the surface.
- Lift tropicals before the first hard frost—tropical lilies, tropical marginals, tender floaters—and move them indoors or store their tubers cool and frost-free.
- Sink hardy lilies, lotus, and hardy marginals to the deepest, non-freezing zone of the pond, below the ice line.
- Net the pond before leaves fall to keep decaying tree leaves out of the water, and skim out debris that’s already in.
- Thin hardy oxygenators and remove dead floating-plant material so there’s less organic matter to decay under the ice.
- Stop feeding fish once the water stays below about 50°F—their metabolism slows and uneaten food fouls the water.
- Keep a hole open in the ice all winter with a floating de-icer or a bubbler/aerator so toxic gases can escape and oxygen can enter. Never smash the ice, which sends shockwaves that can kill fish—melt a hole with a pan of hot water if it seals over.
For more on building and balancing the planting in the first place, see our Water Gardens & Ponds hub, and if you grow vigorous surface plants, our guide on how to grow floating heart in a pond covers the containment that also makes fall cleanup easier.
Troubleshooting
Plant didn’t return in spring? Most often it was a tropical left in a freezing pond, or a hardy plant whose crown sat above the ice line and froze solid—next year sink hardy crowns deeper and lift tropicals. Stored tropical tuber went soft and rotted? Storage was too wet or too warm—keep tubers barely damp (not wet) in a cool 50°F-ish dark spot and check them monthly, discarding any with rot. Lotus tuber died over winter? Usually it froze or you cut the stems below the waterline and let water into the hollow rhizome—leave stem stubs above the surface and keep the tuber in non-freezing water. Water turned foul and fish struggled under ice? Decaying foliage used up oxygen and the ice sealed in gases—do a thorough fall cleanup, net out leaves, and run a de-icer or aerator. Indoor-overwintered tropical lily looks pale and leggy? Not enough light or warmth—give it a sunny window or grow light and keep the water around 65–70°F until you can move it back out. Sort hardy from tropical, match depth to your zone, do a clean fall shutdown, and keep that hole in the ice open, and your pond planting comes back strong every spring.
Frequently Asked Questions
Do I have to take pond plants out for winter?
Only the tropical ones. Hardy plants—hardy water lilies, lotus, and hardy marginals and oxygenators rated to your USDA zone—can stay in the pond as long as their crowns sit below the ice line in water that doesn’t freeze solid, usually meaning a pond at least 18 to 24 inches deep. Tropical plants such as tropical water lilies, umbrella palm, water hyacinth, and water lettuce will be killed by frost and must be lifted and kept warm and bright indoors, or treated as annuals.
How deep do hardy pond plants need to be to survive winter?
Deep enough that the crown or tuber stays in liquid water beneath the ice all winter. In mild zones a foot of water over the crown can be enough, but in cold-winter regions aim for 24 inches or more, placing baskets in the deepest part of the pond. Ice forms from the top down, so as long as the plant sits below the depth that freezes solid it will go dormant and resprout in spring. Shallow container ponds freeze through and cannot overwinter plants in place, so those must come indoors.
How do I overwinter a tropical water lily?
Two ways. The easiest is to keep the whole plant growing indoors in a tub or aquarium in a warm, very bright spot, with the water held around 65 to 70°F. Alternatively, after the foliage dies back, lift the plant, find the small walnut-sized tuber, clean it, and store it damp in distilled water or moist sand in a cool, dark place around 50 to 55°F, checking for rot. Pot it up indoors in late winter and move it back to the pond once the water is reliably above 70°F.
Should I cut back pond plants before winter?
Yes. Trim the dying foliage and spent flower stems off water lilies, lotus, and marginals in fall so the decaying leaves don’t collapse into the water and foul it under the ice. Leave a few inches of hollow stem above the waterline on lotus and on rushes, since cutting them below the surface can let water into the crown or tuber and cause rot. Also thin excess oxygenators and net out fallen tree leaves to reduce the organic matter breaking down over winter.
How do I keep a pond from freezing over and harming fish?
You don’t need to keep the whole surface open, just a hole for gas exchange. Use a floating pond de-icer or run a bubbler or aerator to keep one area ice-free so toxic gases from decaying matter can escape and oxygen can enter. Never smash or hammer the ice to open it, because the shockwaves can injure or kill dormant fish. If the surface seals over, melt a hole gently by setting a pan of hot water on the ice until it opens.