How to overwinter pond plants?

The Pond Guy’s Blog

Plants must not come into contact with ice or freezing temperatures.

Water Garden & Features Q & A

Q: How do I “overwinter” or get my pond plants ready for the winter?
– Maryann in Wisconsin

A: If you live in cooler climates – even those that don’t dip too far below freezing – it’s almost time to prepare your plants for winter. Each type of aquatic plant needs to be cared for in a different way, but the most important factor to remember is that the roots of your plants must not come into contact with ice or freezing temperatures. If they do, they simply won’t survive.

Keeping in mind regional variances, here’s how to keep your aquatic plants healthy, happy and ready to bloom again next spring:

    1. First, remove any dead leaves from the plants growing around your pond. Give bog plants, like irises and taro, a good inspection and clip off any unhealthy growth, spent leaves or blooms. You want your plants to go into winter as healthy as possible so they emerge strong and stout in the spring.
    2. Next, pull on your waders and tend to your hardy water lilies. Pull them out of your pond and trim them to about 3 inches above the root system. When you’re done, move the pots or baskets to 18 inches deep or lower, where they’ll be warm and safe from winter frost.
    3. If you have tropical and floating aquatic plants, like tropical lilies or lotus, it’s easiest to treat them as annuals: Remove them from your pond and mulch the soil and root balls. In most climates, they won’t survive the cold winter conditions. You can try to overwinter them in your shed or garage, but it can be difficult, as many of the tropical varieties require temperatures above 60 degrees Fahrenheit and strong light to survive.
    4. Treat floating aquatic plants, like water hyacinth and lettuce, as annuals, too. Fortunately, they’re relatively inexpensive to replace year after year.
    5. For hardy lotus, trim back the foliage after they have gone dormant and turned brown. Don’t trim them while the plant and leaves are still green, as it can cause it to be susceptible to diseases that creep in through the hollow stems. In cooler climates, move your plants to a cool, but frost-free area in your yard or the bottom of your pond, along with your water lilies.

Depending on the size of your pond and the number of plants you have, this winterizing chore shouldn’t take longer than an afternoon, but you’ll be rewarded in the spring with healthy growth that will once again beautify your outdoor living space!

POND TALK: Have you ever overwintered your tropical water lilies indoors? How did you do it?

Over Wintering Your Plants Hardy Plants

Hardy plants are perennials and can be kept for many years. Some varieties may require extra protection due to differences in your zone and actual microclimate of your pond.

Plant Hardiness Zones for many areas in Ontario are shown to the left.

For more information on Hardiness Zones visit the Agriculture and Agri-Food Canada website at:

Hardy Water Lilies and Lotus
Hardy water lilies and lotus will overwinter if their roots do not freeze solid. Foliage will die back mid to late fall but roots will remain alive. Steps to overwinter lilies should be taken at this time. DO NOT COVER the pond or bring plants inside until late fall when dormancy has begun.


A. Move containers to the deepest area of the pond. Remove dead leaves on lilies but not on lotus. It is recommended that your pond be at least 2 1/2′ to 3′ deep in one area if this method is chosen. Colder zones in Canada should increase this depth. You may cover pond with boards or framed plastic to provide extra insulation. Do not make airtight. Return containers to original positions in spring.


B. Use this method if your pond is shallow and will likely freeze solid. Remove the old leaves from the lily and bring planted containers indoors to cold storage, approximately 40°F (5°C), for the winter. Keep containers moist and dark at all times. More lilies are lost from drying out than from freezing. Return plants to the pond after the ice has melted the following spring.

NOTE: Northern sections of Canada should bring plants indoors or use a pond heater just to be safe.

Hardy Shallow Water Plants
Some hardy shallow water plants can tolerate being frozen solid while others need their roots or tubers to remain in the water. Irises, Rushes (except Pickerel Rush), Sweet Flag, Cattails, Horsetail, Marsh Marigold, Bulrush, Houttuynia, Golden Creeping Jenny and Buttercup, Watercress and Water Forget-Me-Not may be left in shallow water where they will likely freeze. Most other varieties should be moved to deep water or brought indoors to cold storage. (See method B above.) Return all plants to growing shelves as soon as the ice has melted in the spring.
NOTE: Do not remove dead leaf stocks from emergent plants such as cattail and rushes until spring. This will allow the root system to “breathe” during the winter.

Tropical Plants

May be grown outdoors during the summer, but are considered annuals unless heated greenhouse facilities are available.

Tropical Water Lilies
When brought indoors, tropical water lilies and plants continue to grow during the winter months and must receive sunlight and heat. Growth slows considerably in December and January when there is very little sunlight and the leaves will become yellow and small. Most people treat tropical water lilies as annuals due to the considerable effort required for their continual growth.

Method: Before the first heavy frost in your area, bring the tropical lily indoors to a heated greenhouse or sunroom. Place the containers in a tank, fertilize sparingly and ensure water temperature will not fall below 21°C (70°F). This will prevent the lily from going into a dormant state even though growth slows considerably. The following spring when the pond water temperature has warmed to a consistent 21°C (70°F), in early June, place the lily back in your pond.

Tropical Shallow Water Plants
Like tropical water lilies, shallow water plants must continue to grow during the winter months. Growth will be reduced considerably as daylight hours diminish. Umbrella Palm, Dwarf Papyrus, Little Giant Papyrus and White Arum lilies will survive the winter indoors and make excellent houseplants. Other varieties are best treated as annuals.

Method: Remove tropical plants from the pond before the first severe frost and bring indoors to a heated greenhouse or sunroom. Plants must remain in water and be kept at a temperature of approximately 18°C (65°F). Remove old growth if it yellows. Return to the pond in spring when there is no risk of frost.
NOTE: Small amounts of fertilizer may be required to encourage plants to keep growing during the winter.

Many people treat Tropical Shallow Water Plants and Water Hyacinths as annuals due to the cost and effort required to overwinter. Simply compost plants in the fall and restock the pond the following spring.

Water gardeners in Canada frequently use the previous overwintering methods for plants. These suggestions can be used alone or in any combination to best suit your own situation. There is no guarantee that your plants will survive the winter. By trying these commonly used methods your chances of success will be increased. We would be glad to hear from you if you have found other successful ways to winterize your plants.

  1. Hardy water lilies will go dormant for the winter. The foliage will die back or become sparse. When this happens, move the water lily, pot and all, to the deepest part of your pond, where the water doesn’t freeze solid. Hardy water lilies actually enjoy a cold, dormant period. Leave it there for the winter and fish it back up as the water warms in the spring. It should resume growing sometimes around April.
  2. If you don’t have a deep enough pond to keep the water lily below the freezing level, you can try one of these other methods to protect it.
    1. Take the water lily out of the pot and bury it completely in the ground. Mark the spot, mulch it well, then dig and repot the plant in the spring. (We’ve never tried this and suspect a lot depends on the type of winter you have. A good snow cover should keep it fine, but a dry, cold winter could kill it.)
    2. If it’s a small pond, you could insulate the whole pond by covering it with boards and then a layer of straw or old blankets or rugs. Be sure to remove all the coverings as early in the spring as possible or it will heat the water and cause premature sprouting. (This sounds like a lot of work, but think of all the work you save by not having to scoop leaves and debris out of the pond in the spring.
    3. Bring the water lily indoors for the winter and store in a cool basement or heated garage, about 50 degrees F. Either bring in the whole pot and place it in a plastic bag or box. Check it periodically to make sure the soil remains moist. Or remove the plant from the pot and store the tuber in moist peat moss or leaves. (Don’t expect your potted water lily to make a good houseplant. It still needs to go somewhat dormant and won’t be particularly attractive.)

The Best Winter Hardy Pond Plants Species (Top Cold Weather Picks)

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Unlike tropical plants, hardy plant species will tolerate and survive even the harshest of winters.

An essential component of aquatic ecosystems, including your garden pond, are plants! They aid in oxygenating the water, filtering out pollutants and excess nutrients, and provide shade, food, and shelter for your pond’s inhabitants. However, different species are of course best adapted to certain climates, and depending on your location you may need to choose plants that are able to survive winter. To determine which plants will do best in your region, you should consult a plant hardiness zone map.

In short, there are 13 different hardiness zones in the United States, and each zone is broken up into two sort of sub zones (A and B) to account for slight variations within each zone. Zones 1a to 7a experience average annual extreme minimum winter temperatures as low as -60 degrees Fahrenheit to 0°F, respectively (essentially, these zones often have winter temperatures below zero degrees), while zones 7b to 13b range from 0 to 70°F, respectively (with 7b being 5 to 10°F and 13b ranging from 65 to 70°F). An image of the US pond plant hardiness zones can be found below (click for larger size):

Depending on your hardiness zone, some species of plants will tolerate thefrost and cold weather better than others.

Similarly, Europe has 8 hardiness zones, and Canada has 10 – this is due to the absence of any subtropical zones in these regions, like those found in portions of the southern United States. After determining which hardiness zone you’re in, you can then conduct some simple research to figure out which plants are best for your pond and climate! For example, if you live in zone 3 you certainly wouldn’t want to attempt having tropical plants in your pond unless you are able to move them indoors for the winter (which can be a hassle to do, might be hard on the plants, and could also cause stress to your fish as part of their habitat is being removed).

Benefits of Cold Weather Pond Plants

Hardy pond plants won’t die off in winter, which means less cleaning, shelter, and year-round oxygenation.

If you live in a cold weather zone, having plants that are either well adapted to the cooler climate, or are perennial and thus return year after year, will provide a variety of advantages. Economically, you won’t have to spend money replacing a bunch of plants in the spring. They’ll also provide water filtration and oxygenation year round (this is especially important in winter, as ice and snow can lead to a decrease in dissolved oxygen levels in the water).

In addition, they won’t die off and therefore won’t deplete oxygen, add nutrients to the water, and won’t create extra work for you having to clean them out of your pond and filters after they die. They’ll also provide beneficial habitat and possibly some food for your fish throughout the winter, depending of course on both the plant and fish species.

List Of Winter Hardy Pond Plants (Cold Weather Species)

Here we will cover some of the best floating, marginal, bog, and submerged pond plants for regions that experience cool or cold winters.

1) Water Lilies (Nymphaeaceae nymphaea)

This particular genus (nymphaea) of water lilies is well adapted to cooler/cold climates (typically zone 3 and warmer). With thick rhizomes that are able to subsist in substrate throughout winter and resprout new lilies the following year, hardy water lilies are floating plants that make an excellent choice for cold weather ponds. Their broad leaves provide protection from both the elements and predators, while their long stems and extensive rhizomes are nibbled on by some fish and their flowers are valuable to pollinators. However, because of these thick rhizomes, water lilies are able to grow quickly and can both overtake a pond and be difficult to get rid of. You’ll have to either regularly cut them back, or dig up some of the rhizomes in the spring before they sprout. Alternatively, you could plant them in pots placed on the bottom of the pond that will limit their spread.

2) Water Hyacinth (Eichhornia crassipes)

Water hyacinth is a resilient, highly adaptable free-floating plant that is well suited for both cold climates as well as those near the equator. Many fish like to munch on hyacinth, but that’s often considered beneficial because of this plant’s ability to reproduce and disperse quickly. Because of their hardiness, water hyacinth are exceptionally easy to have and require very little care, other than having to potentially manually cut them back to prevent overcrowding if your fish aren’t eating enough of them to keep their growth in check.

3) Hornwort (Anthocerotopsida)

Also considered to be one of the most effective oxygenating plants, hornwort is a submerged plant that will also stay green throughout winter in most zones, providing oxygen and shelter. It’s not generally browsed on by fish, nor does it reproduce overly quickly, so you’ll have little to worry about in terms of care of maintenance with this plant, during winter or otherwise. They’ll either float freely about the pond, or you can weigh them down with small weights so that they stay put and don’t wind up in your filters.

4) Frogbit (Hydrocharis morsus-ranae)

A floating plant with heart shaped leaves that resemble miniature water lilies, frogbit has evolved a unique and effective method of overwintering. As temperatures begin to cool toward the end of summer, frogbit will develop structures called turions, or buds, that drop off of the plant and sink into the substrate at the bottom of the pond. These buds will remain protected through winter by the mud or other substrate, and are able to give rise to as many as 10 new plants the following season that can cover over a square meter of area per bud. With this in mind, you may want to remove some of the buds to prevent them from taking over your pond, or manually remove some of the new growth in the spring. In addition, in some areas frogbit is considered invasive, and so you should check online to make sure that you can legally have it in your area, as well as take precautions so that it doesn’t spread into natural areas where it can wreak havoc.

5) Horsetail (Equisetum)

Horsetail, also known as scouring rush, is a prehistoric plant that’s been around for many millions of years. As such, it should come as no surprise that these plants are well equipped to persist through winters as harsh as zones 3 and 4. They’re considered marginal, preferring to grow either in damp soil or water that is only a few inches in depth. Like water lily, horsetail also has rhizomes. This is how they’re able to overwinter, as the main portion of the plant will die off while the rhizomes sit dormant in the ground or the bottom of your pond, giving rise to new growth the following season. Horsetails have native species on every continent except Antarctica, and so they generally don’t grow out of control like an invasive species would. If you do find them spreading a bit more than you’d like, you can always pull up some of the rhizomes – they’re not as thick or matted as that of water lily or cattails, so it shouldn’t be as difficult to remove them. In addition, their segmented anatomy makes them quite adept at filtering water.

6) Water Hibiscus (Hibiscus coccineus)

Also known as swamp hibiscus, this plant is classified as a bog plant that prefers to grow either in saturated soils or a couple inches of water. Water hibiscus has large, dramatic flowers that are typically red, pink, white, or some combination thereof. They provide shade (and therefore temperature regulation) along the edge of the water, as well as some protection from predators, while their striking flowers attract local pollinators. As a perennial plant, coccineus will die off each fall, but will sprout again in the spring via seeds that have been known to survive winters that reach as frigid as -30°F (zone 4).

7) Water Plantain (Alisma paviforum)

American water plantain, is a marginal plant with large, oval leaves, long stems, and very small pink or white flowers. Also a perennial, paviforum will die off in mid to late autumn, though its seeds will persist through winter and are hardy in zones 3 through 9. Additionally, the submerged portions of the plant provides habitat for aquatic invertebrates, which are in turn eaten by fish, frogs, birds, snakes, and so on. While aquatic baby’s breath specifically encompasses only American water plantain, the common water plantain has similar characteristics and has native species throughout much of the world, including North America, Europe, and portions of Asia and Africa.

8) Water Soldier (Stratiotes aloides)

Another floating plant, water soldier is also known as water aloe or water pineapple due to its protruding, long spiky leaves. Though they look rather like a tropical plant, water soldiers have also developed an interesting adaptation to survive winters, even those that delve into the negative digits. As water cools in the autumn, the main leafy portion of the plant becomes saturated with water, causing the plant to lose its buoyancy and sink to the bottom of the water, where it’s able to survive ice so long as the water is at least a few feet deep. However, water soldier is native only to Europe and Asia. The other native plants in these areas have adapted methods of competing with water soldier so that it doesn’t crowd them out. If you live in Canada, water soldier is considered highly invasive and possession of it is prohibited; it’s also invasive throughout much of the U.S., though some states have wild, natural populations and allow it to be used in ponds. In areas where it’s not considered native, local plants have not evolved to be able to compete with it and as such water soldier is detrimental to ecosystem health.

12 Floating Pond Plants – hardy and nonhardy varieties


Floating pond plants are often beautiful looking, delicate plants. The fact that they don’t stay in one spot, but rather move freely on the water surface, adds to their attraction. Their movements are solely determined by the wind and flow of the water.

These aquatic plants can help to shadow your pond, particularly when there are no trees or other structures which provide shade. By reducing the amount of sunlight hitting the water, floating pond plants help to reduce algae, which need the UV for their growth. They also reduce algae by outcompeting them for the nutrients solved in the water.

Smaller plants often serve as food for water birds or bigger fish, such as koi. Floating pond plants also provide cover for fish eggs, fry or smaller fish.

But floating water plants have their downsides too. Most of them reproduce very quickly. Instead of only being dependent on pollination, they achieve their rapid reproduction by propagating via offshoots or by bigger plants splitting up into two new plants. Because of their high reproduction rate, they are often considered invasive species outside their native habitats.

Adverse side-effects of this severe overgrowth are a reduced gas exchange at the air-water interface. A large number of floating pond plants on the water surface not only blocks the sunlight from algae but from reaching submerged water plants too. These plants then can no longer produce oxygen, which has negative implications for your fish. When this condition lasts too long, your immersed water plants eventually die, and the water gets saturated with sludge gas. This toxic environment will ultimately kill off your fish and will leave you with a pond which seems lively at the surface, but is essentially dead below.

In your garden pond, you can control their growth manually by using a scoop or spoon net and dislodging excessive plants when needed. If you have bigger fish, such as koi carps or goldfish, they might feed on your floating plants – thus reducing their numbers naturally. Using chemicals to kill off your floating plants should always be considered as a last resort. You have to be very careful not to harm your other plants or fish. Additionally, the dead plants will sink to the bottom of your pond and start fouling the water.

Another possibility to control these plants is by using non-hardy varieties. Of course this only works, when you live in an area with cold winters. Plants from warmer climates won’t survive the winter, which puts a natural end to their propagation. But again, you should scoop out most of the plants manually before frost sets in. Otherwise, the dead plants will start fouling, creating a toxic environment for your fish to overwinter in.

So when adding floating plants to your pond, we would strongly recommend you stick to varieties native to your area. They are often dispersed to new waters by water birds. Their roots or offshoots can stick to the feet or plumage of these birds and are then carried away to new sites.

In many countries, some floating plants are considered as pests or at least as a nuisance. Particular plants are even banned from sale in certain countries. In the descriptions listed below, we give indications to the natural habitats of the plants. If you are still unsure which floating plants are best suited for your pond, seek advice from a local wildlife agency or an established gardening expert.

Winterizing Water Plants: Care Of Pond Plants Over Winter

Many home gardeners include a water feature, such as a pond, to add interest to the landscape and create a relaxing oasis to retreat from the chaos of daily life. Water gardens require year-round maintenance, even in winter, and unless you are lucky enough to have a professional groundskeeper, this chore will fall to you. A big question is how to winterize pond plants?

How to Winterize Pond Plants

The question of what to do with pond plants in the winter depends upon the plant. Some plants will not tolerate winter temps and must be removed from the pond. For cold hardy specimens, overwintering pond plants may simply mean immersion in the pond.

Before winterizing water plants, it is a good idea to manage the water garden itself. Remove dead leaves and dying plants. Inspect any pumps and change filters as needed. Quit fertilizing the water plants when the daytime water temp drops to below 60 degrees F. (15 C.) to give them time to become dormant.

Now it’s time to categorize the water plants to determine a course of action for caring for pond plants over winter.

Cold tolerant plants

Plants that are cold tolerant can be left in the pond until the top is frost damaged, at which point prune all the foliage off so it is level with the top of the pot. Then lower the pot to the bottom of the pond where the temperature remains a few degrees warmer throughout the winter. Lotus and hardy water lilies are an example of water plants that can be treated in this manner.

Non-hardy plants

Plants that are non-hardy are sometimes treated as you would annuals. That is, remanded to the compost pile and replaced the next spring. Water hyacinth and water lettuce, which are inexpensive and easy to replace, are examples of these.

Overwintering pond plants, such as lily-like aquatics, need to be submerged, yet warm enough. A good idea is to submerge them in a large plastic tub in the greenhouse, warm area of the house or use an aquarium heater. Examples of these are floating heart, mosaic, poppies, and water hawthorne.

Winterizing other non-hardy water plants can be accomplished by treating them as houseplants. Some examples of this are sweet flag, taro, papyrus and umbrella palms. Just keep them in a water-filled saucer and place in a sunny window or use a grow light on a timer set for 12-14 hours a day.

Caring for delicate pond plants, like tropical lilies, over winter is a bit more difficult. These beauties are only hardy to USDA zone 8 and higher and like a water temp of 70 degrees F. (21 C.) or greater. Air dry the lily tuber and remove the roots and stem. Store the tuber in a jar of distilled water in a cool, dark area (55 degrees F/12 degrees C). In the spring put the container in a warm, sunny place and watch for sprouting. Once the tuber sprouts, set it into a pot of sand and sink this into a container of water. When leaves have grown and white feeder roots are visible, replant into its regular container. Return the lilies to the pond when water temps are 70 degrees F.

For a lower maintenance pond, use only hardy specimens and be sure to install a deep enough pond for overwintering and/or install a water heater. It may take a little work, but it’s well worth it, and in no time spring will return as will your water garden sanctuary.

For a new twist on the backyard flower garden, turn your attention to floating aquatic plants like the water hyacinth (Eichhornia crassipes), an aquatic perennial. hi guys, I bought a few hyacinths early this year and they have multiplied like crazy. I intend to cover the pond completely with plastic and will. To divide large clusters of water hyacinths, you just pull them apart. Winterizing Water Plants: Care Of Pond Plants Over Winter – Water gardens require year-.

I doubt that water Hyacinth can be stored dry for any length of time, but has anyone ever try bringing them indoor for the winter? I know someone that brings them in, with his fish and other plants. I think they had it in an aquarium w/light warmth and by a south window. Your water lilies and hyacinth put off big blooms, your irises and cattails became homes for frogs and dragonflies, and your submerged plants. For a new twist on the backyard flower garden, turn your attention to floating aquatic plants like the water hyacinth (Eichhornia crassipes), an aquatic perennial.

I have the green water issue and have come to the conclusion that if I can’t winterize my floating plants, thus having to buy a whole bunch of. Water hyacinth (Eichhornia crassipes) is both a popular and problematic floating plant that grows as a perennial in U.S. Department of Agriculture plant. Growing water hyacinths in an ornamental water garden.

i have one little piece of hyacinth and 3 lettuces that i threw on top of my pond to float. somebody at the green house told me i need to put all my. water hyacinth (Eichhornia) and water lettuce (Pistia) are excel- lent additions to the compost pile, adding nutrients and water, and degrading quickly. Other. Take the appropriate steps to ensure your water plants and fish overwinter properly. Treat Water Hyacinths and Water Lettuce as annuals, replace every year.

Water Hyacinth

By Josh Spece

Common Name: Water Hyacinth

Latin Name: Eichhornia crassipes

Hardiness: zone 9 (20*F)

Light: Sun for best flowering and compact growth, but will grow just fine in shade.

Size: 6 in. to 2 feet or more

Notes: Water hyacinths are one of the most common plants seen in water gardens. This floating plant is native to South America and very sensitive to cold weather. Water hyacinths have round, glossy green leaves held on upright, fleshy stalks. Short plants usually have a large “ball” at the base of each leaf. This, along with the fleshy stem, is filled with styrofoam-like material that keeps the plant afloat. Beneath the water is a large, feathery root system that is usually black or purple.

Water hyacinths are very useful at competing with algae. Their fast growth rate allows them to quickly shade the water while at the same time absorbing huge amounts of nutrients from the water.

Hyacinths are usually very easy to grow, but some people have trouble getting them to grow and bloom. Fish love to nibble at the roots. If the fish are large or there are a lot of them, they may kill the plant or even eat the entire thing. Placing the hyacinths in floating baskets or partitioning them off from the fish with rocks may help.

Water hyacinths love to be crowded and even though they are floating plants, they don’t like to drift around. Corralling them with a hoop of plastic tubing, a hula-hoop, fishing line, or even rocks will keep them from moving around.

Water hyacinths usually bloom the most during the hottest part of the year and only if they are crowded. Each 6” to 12” flower spike lasts only one day and has 6 to 15 lavender flowers on it.

Yellowing hyacinths are a common problem and it is caused by lack of nutrients. Hyacinths are such vigorous growers they sometimes use up one or more nutrients in the pond. This can especially be a problem in very small ponds and ponds with very few fish. There are two ways of fertilizing your hyacinths. If you only have a few hyacinths, you can float them in a bucket of Miracle Grow for a few hours at a time. If you have too many hyacinths to remove from the pond, you can treat the entire pond with a solution of Muriate of Potash. Flora Boost is a commercially produced potassium supplement. Hyacinths and other floating plants also usually respond well to any of the micro nutrient solutions specially made for pond plants.

A more common problem is water hyacinths growing too well and crowding out other plants. In ideal conditions, water hyacinths can double in mass in as little as 6 to 14 days! In a small backyard water garden, it is easy enough to just remove excess hyacinths as needed. In areas that remain frost-free year round, water hyacinths are considered a major pest. Many southern states have banned them completely. For this reason it is very important never to place water hyacinths in a natural body of water!!

Varieties: There are very few varieties of water hyacinth and none of them commonly available. The Peacock Water Hyacinth (Eichhornia azurea) is very similar to the common variety. It remains smaller and forms a creeping mat on the water surface. The plant lacks the swollen stems of the common hyacinth. May prefer to be potted in soil as opposed to free floating. The Peacock Hyacinth is said to be freer flowering with more attractive blooms than the common species. There is also a white flowered water hyacinth, but it is very rare.

Winter Care: Trying to overwinter water hyacinths in cold regions is usually more hassle than it’s worth. They are cheep enough and grow fast enough during the summer that it is usually easier and more cost effective to buy new ones each spring. If you want to try keep hyacinths over winter they need a warm spot that is brightly lit. A South window is best, but artificial lighting may still be necessary. Fluorescent shop lights 6” above the plants is about right. Some people have reported success by putting a couple inches of compost in the bottom of the container the hyacinths are in. Others actually pot the hyacinths and submerge the pot so the rim is an inch or two below the water surface.

Propagation: division

  • Remove all dead plant material. This should be done throughout the year. To keep fall leaves from filling the garden, drape a fine net over the garden, before the leaves start to fall. I raise mine a little, with an arched PVC pipes, so that wildlife, like frogs and birds, do not get trapped underneath. You can then lift the net and most of the leaves. Clean the remainder with a long handled net or skimmer.
  • If there is an excessive amount of debris on the bottom of your garden, you can try using a vacuum, but you may need to drain and clean it. Before you do, test the water pH and temperature. Move any plants and fish to a temporary holding bin. Drain and clean the pond. This is also a good time to check if any repairs are needed to the lining. Then refill with water and wait until the temperature and pH have adjusted back to pre-cleaning numbers, before returning the fish and plants to the pond. The plants can go back into the deepest section of the pond. Reintroduce the fish slowly as you would with any new fish.
  • If you are in an area where the water in your water garden will freeze, you will need to prevent the entire surface from freezing solid. Plants and fish need oxygen, even during the winter. You have several options for keeping an opening in the ice.If you only occasionally get hard freezes, you can keep the pump running or use a bubbler.
    Areas with hard winters should not keep their pumps running, because the tubing can freeze and burn out the motor and it can also crack, particularly if there is repetitive freezing and thawing, expanding and contracting. (Now is a good time to clean the pump and filters.) In lieu of the pump, you will need to use some type of floating de-icer. There are electric, battery powdered and solar options available, but make sure there is enough regular sunlight, before trusting to a solar de-icer. An aerator is also advisable, if you have fish.
  • Monitor the water level, throughout the winter. If the level drops by several inches, you will need to top it off, to protect the submerged plants and fish.

Winterizing Your Pond

By Josh Spece

Water gardens are fairly low maintenance when compared to regular old dirt gardening, but there are some extra precautions you should take to make sure your water garden and its inhabitants survive our harsh winters with flying colors.

Fall is a very important time of the year when preparing your water garden for winter. It is best to have your pond go into winter as clean as possible. You should try to keep as many falling tree leaves out of your pond as possible by netting them off the surface of the water or stretching a mesh net over the pond. A wooden or pvc frame to stretch the mesh over is very useful. By having the netting tight the leaves tend not to weight it down and sink into the water. If the leaves lay on the net and are in the water, they can make your water tea-colored with tanic acid (NOT GOOD!). Also remove all dead flower heads and yellow/brown lily leaves. This should be done monthly during the active growing season to keep the pond clean and healthy. After a light frost you can remove all the water lettuce and water hyacinths, as they will turn yellow/brown and sink. Plant material that sinks to the bottom and rots will cause a deadly gas that can kill your fish.

In this area (zone 4) it is a risk to leave your lilies and fish outside in a pond less than 3’ deep. A severe winter could freeze a shallow pond almost solid and kill all your lilies and fish. If your pond is at least 3’ deep you can leave your plants and fish out all winter (place lilies in deepest area), but you will need some way for gas exchange to take place. Methane gas is produced by decaying plant material and is deadly to fish. Just because your fish aren’t very active, they still need plenty of oxygen in the water. You can provide gas exchange and fresh oxygen several ways:

  1. Keep your recirculating pump operating all winter. Set your pump on an upper level about 12″ under the water, making sure the water coming out of the pump is breaking the water’s surface, or place an attached hose so that it creates a lot of surface disturbance. The splashing causes the gases to escape and lets oxygen back into the water. This is our personal recommendation!
  2. Place a tank heater in the pond to keep an opening in the surface. This can be very expensive to run and is usually only necessary in extremely cold weather.
  3. Place an air pump outside the pond and place an air stone in the pond to keep introducing fresh oxygen to the pond. This method will allow the pond to freeze over during extreme cold temperatures but still supply the badly needed oxygen.

You can use any combination of the above ideas for extra security.

NEVER BREAK ICE FORCIBLY!! Shock waves will stress the fish, injure their gills, and possibly kill them. Use hot water to melt a hole in the ice if necessary.

Leave fogs outside; they need to hibernate by burying themselves in the mud. If you let them find their own place to spend the winter they will be back next year.


If you decide to remove your fish for the winter there are a few things you should remember:

  • You will probably have to remove all pots from the pond and at least partially drain it while you are trying to catch the fish. They are fast and very good at avoiding the net.
  • When introducing your fish into the aquarium make sure that the water temperature of the pond and the aquarium are very similar and the filtration system is established. If you are on city water make sure you use Aqua-Safe to remove chlorine, chloramine, and ammonia, or let the water stand for 24 hours.

When placing koi and catfish in any kind of tank or container it must have some sort of lid because they will jump out. A floating block of styrofoam is also said to prevent koi from jumping. With goldfish and fantails there doesn’t seem to be a problem with them jumping. Fish in tanks need adequate oxygen and filter systems. When fish are taken indoors make sure to locate them where it is easy to change at least 1/3 of the water monthly, especially if it is over crowded and the fish are large. Guppies, tropical snails, and plecostomus should be brought in when the daytime highs do not get above the 50’s.


Tropical bog plants will need to be taken inside and kept actively growing. Tropical plants need light from the outdoors, next to south windows, or a minimum of four 4’ fluorescent tubes kept within a few inches of the plants. Make sure the tropical plants are kept wet. They don’t necessarily need to be setting in water, though. They are not growing as actively so they can tolerate a little dryer soil.

Once the hardy water lilies have gone through several frosts, they should be stored in a cool, dark area where it does not freeze and kept wet. To store properly, make sure the soil is moist, cover the crown with wet newspapers or cloth, and place in a garbage bag in a cool, dark area and check it at least once a month to make sure it has not dried out. Then, as soon as your pond is free of ice, put the lilies back in the pond (March or April). They will start growing sooner if put in the pond after the threat of extreme cold temperatures has past. If the lilies are kept in the house any longer, their growth and flowering will be slowed. It is best to over winter all hardy plants outdoors if at all possible!!

Tropical lilies need special treatment to over winter successfully. Before your pond freezes over, move your topical lilies, pot and all, to an area that will not freeze and forget it for about a month. During this time the soil is going to dry and the lily is going to form a small tuber about the size of a walnut. Once the lily has dried out, find this tuber. Place it is a jar or ziplock bag of barely damp peat moss and store in you refrigerator or an area that stays between 40 and 50 degrees. Check once during the winter to make sure the tuber doesn’t get too dry or has not rotted.

About the first of April, bring your tropical water lily tuber out of storage an place it is a container of warm water in a sunny window. Soon small shoots will begin to grow from the tuber. As soon as the big enough to easily handle and have a couple roots, remove them from the tuber and pot. Submerge the potted lilies so that a couple inches of water covers the soil. Do not place them in your pond until the water temperature stays above 70 degrees…about June 1st, here in Iowa (zone 4).

Completely submerged plants such as Curled Pond Weed and Hornwort are hardy. No other varieties will survive the winter.

After their leaves turn brown, hardy marginals (bog plants) can be trimmed back. Never cut plants with hollow stems off below the water level, because they will die if completely submerged (cattails, rush, and pickerel rush). All other plants can be placed on the bottom of the pond to over winter. The following plants should make it over the winter in ponds at least 3’ deep in zone 4: cattails, water iris, arrowhead, arrow arum, dwarf bamboo, bog arum, bog bean, bullrush, creeping jenny, goldenclub, lizard’s tail, variegated manna grass, marsh marigold, giant bur reed, flowering rush, horsetail, pickerel rush, soft rush, white rush, zebra rush, sweet flag, water cress, water celery, variegated water celery, water hawthorn, and water mint. Floating heart, thalia delbata, pennywort, and parrot’s feather if roots are below ice.

Frogbit is an unusual plant. It produces a small potato known as a resting bud or turion that stores food and become detached from the parent plant to pass the winter in the mud on the pond floor. If you remove the bottom mud from your pond in late winter, you will also be removing the resting bud. To over winter, collect some of the buds and store in moist soil in a frost-free place. Once new shoots form, return to pond or if left outside they will float up to surface.


How to Keep Pond Plants Safe Until Spring

“When do I put my aquatic plants to bed for the winter?” This is one of the questions our customers ask us the most at Allendale Aquatic Nursery & Koi. To ensure beautiful plants next spring and summer, all aquatic gardeners should follow a few steps now before the weather turns too cold and blistery.

By Mike and Vicki Tiano, Allendale Aquatic Nursery & Koi, Allendale, MI Originally published in EasyPro’s Passion for Water, Fall 2008 – Revised Fall 2019

Hardy Pond Plants

Hardy marginal plants can easily be winterized by first removing dead foliage down to the crown of the plant. Next, trim back any foliage that is not dead to a height just above the water level. Replace the plant in the same spot it was in all summer. This procedure can be followed for most hardy marginal plants such as rushes, reeds, cattails and iris.

Marginal Pond Plants

Some hardy marginal plants should be wintered at the bottom of the pond or in two feet or more of water. For water gardeners who live in Zone 5 or below, these plants include thalia, pickerel, lobelia, melon sword and water parsley. Do not allow the tuber or rhizome of these plants to be subjected to actual freezing of the water or to be covered in ice, as this will cause the plants to turn to mush and they will not return in the spring.

If your pond is too shallow to overwinter your plants, you can place them in a styrofoam cooler. They may be stored in the garage or crawl space at 40°F, but they must be kept cool, dark and damp by covering them and watering them once or twice a month.

Hardy Water Lilies

We recommend our customers trim the long foliage of hardy water lilies down to the crown. You should leave growth near the crown in place for next year’s food source.

When the weather turns cool and the first frost hits the pond, place the pot at the bottom of the pond or at a depth of 18 inches or more of water. If your pond is above ground, you can winter your hardy water lilies indoors. Simply place them in pots in a cooler and keep them moist, cool and dark. If you prefer to winter your hardy water plants in your above ground pond, simply install a pond heater.

Oxygenating Water Plants

Oxygenating water plants that are hardy to at least Zone 5, such as coontail and Italian veil, should be trimmed to three to four inches and left in the bottom of the pond. These plants provide valuable oxygen to the pond when the pond water is warm, thus helping to keep your water clear. They will winter over at the bottom of your pond, or at 18 inches of water or deeper with no extra care needed.

Tropical Pond Plants

Floating tropical plants such as water lettuce and hyacinth should be treated as annuals in your water garden. To overwinter them in the northern climates, the water must be at least 70°F with 12 hours minimum of sunlight daily. You would need an aquarium, a heater and a strong grow light. Even then, they typically make it to February at best before turning to mush. The cost involved is far more than purchasing new plants in the spring.

Tropical, bog and marginal plants can be enjoyed year around. They must be brought inside before the first frost. Trim all dead and leggy foliage. It is acceptable to keep your tropical marginal plants submerged in a container that holds water, but your tropical plants can easily flourish when treated as houseplants. Be sure to water them once or twice a week and keep them in a warm sunny place. There is no need to fertilize your tropical plants because they will not grow much in the winter.

Wintering Tropical Water Lilies

Tropical water lilies are loved by the aquatic gardener for their unique foliage and their exquisite flowers and fragrance. Many pond owners are drawn to tropical water lilies but are hesitant to grow them, assuming they are too difficult to overwinter. There are two options (assuming you do not have a heated greenhouse) to winterize your tropical lily.

Option 1
After the first frost remove the tuber from the soil, trim all leaves from it and let it dry. Lightly spray with a fungicide and again let it dry. Next, bury the tuber in a sealed jar with damp sand and store it in a dark, cool area where it cannot freeze.

Option 2
Treat the tropical water lily as an annual and replace it each year.

We hope these guidelines for winterizing your aquatic plants have put your fears to rest as you prepare your pond for its winter slumber.

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Plant water lilies now

Water lilies are also deciduous. However, as they grow from a rhizome (thick woody stem) covered by at least 20cms water, the roots continue to grow even when the pond is covered in ice. Autumn is a good time to plant a water lily. The root system can then become established over winter, giving it time to get ready for an early start as the water begins to warm up in the spring.

With established lilies, just fish out the dead brown leaves so that they don’t rot down and add to the detritus in the bottom of the pond. If you have any sort of pump or filter system, it is wise to lift the lily baskets and replace any soiled washed out by the movement of the water.

Autumn clear out

For most plants, Autumn is the time to have a bit of a tidy up to prepare for winter. With marginal plants, you can cut browning foliage back to about 4cms above the water surface. Don’t cut any stems back below the water level or the plants may drown. If you have a pond where the water tends to go up and down a bit don’t forget to take account of the normal winter rise in water levels.

Aquatic Plants in Winter

Question: What do I do with my aquatic plants in my backyard pond when the winter weather comes? I have floating hyacinths, some potted shoreline plants and a lily.

Answer: This answer depends on whether you will have frost for a day or two at a time over the winter or whether your pond will freeze for many days at a time during the winter. For all ponds, stop fertilizing plants as the weather cools off and remove the leaves of any pond plants as they turn brown. Don’t let them fall into the water to rot away.

Some of our pond plants are hardy perennials and some are tender annuals, just like the plants in your dry land garden. The really hardy plants like cattails can have the roots frozen solid while the tops die over the winter. Just leave these plants sitting on the shelf or planted right into the rocks and gravel. No matter where you live, they will be fine.

Lotus and hardy water lily plants also have leaves that die for the winter, but the root system cannot handle being frozen or else they will die. These plants need to be set to the bottom of the pond where the roots can stay cold, but not frozen. If the pond freezes too deep, the plants will die. It is best for these plants to go dormant, so don’t try to build a greenhouse to keep them warm. If you only have cold weather for a few days at a time, the plants will start sending up new growth as the water warms up.

For water gardeners in very cold climates, cypress, papyrus, water hyacinth, water lettuce and other tropical plants will need to be moved indoors for the winter or just tossed out like other annuals. Even a cool spell can kill some of these plants. These same plants can stay in a pond with a protective covering thrown over it if the frost is only going to last for a night or two.

In warm climates, the length of daylight can cause some plants to slow or stop their flowering for a few months, so stop fertilizing for the winter and begin again as the day length get longer.

Question: What do I do with our Koi and goldfish for the winter? My wife wants to bring them in, but I thought they were supposed to stay in the pond.

Answer: There are several things to consider when considering keeping your fish in the pond for the winter. First, how many fish do you have? Too many fish, especially small ones, can consume all the oxygen in the water when ice is on top. Second, ponds at least 2 feet deep hold more water and have less of a chance of freezing too deep. More water means more oxygen is available for the fish and deeper water has a larger reserve of heat to help prevent ice from freezing all the way to the bottom. Third, if ice will freeze over the pond for longer than a few days, then a deicer will be necessary to keep a hole in the ice for gas exchange with the atmosphere.

If you want to bring some of the small fish indoors for the winter, you can. Fancy varieties of goldfish also do better if brought in for the winter. It is best to use a large aquarium or tub that can be aerated and filtered properly, and drained easily for water changes. Just like any other aquarium start up, proper water testing is required to prevent toxic chemicals from building up when you first start it running in the fall.

Email questions to Jeff Rugg at To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at

Shorter days and swaths of fall colors mean one thing: winter is on its way, and your aquatic plants will need some attention before the big chill sets in. So bundle up, pull on your hip waders and let’s take care of some winter-prep pond plant chores!
Tropical Plants: Tropical water lilies, water hyacinth, water lettuce and other tropical plants prefer warm temperatures all year long. If you live in USDA Hardiness Zone nine or lower, you’ll need to completely remove these plants from your pond and relocate them to a protected indoor space for the winter, like an aquarium or large bucket inside a heated garage or workshop.
Tropical water lilies will need some extra care. When you pull the plants from your pond, remove any dead foliage, rinse the plant well, keep the tuber moist in distilled water and place it under a grow light until spring.
Keep in mind that despite these winterizing measures, your tropical aquatic plants might not survive the winter. They are from the tropics, after all …
Hardy Water Lilies: Hardy water lilies can tolerate cooler temperatures than your tropical varieties, but they need to be kept in a place that won’t freeze, like the deepest areas of your pond. Remove the plants from the pond, trim the foliage back to one to two inches above the root ball, and submerge them as low as they’ll go for the winter. Come spring, the greenery will reemerge healthy as ever from the plants’ crowns.
Bog Plants: Your bog plants’ leaves and stems will begin to die off as winter arrives, so you’ll need to trim them back to just above the soil with pond scissors. If they are in containers, sink them lower into the deepest parts of your pond where the water remains unfrozen during the wintertime. If they are planted directly into the ground, leave them alone for the winter.
Submerged Plants: The only thing your below-the-surface greenery needs is a quick trim to get rid of decaying and dead foliage. Cut plants in containers back to one inch above the pot and submerge in the center of the pond; any plants living directly in the ground can be left as-is.
Floating Plants: Unless you live in a climate that doesn’t freeze, floating plants like water hyacinth and water lettuce won’t survive the winter. Plan to remove them from your pond after the first hard freeze and toss them in your compost pile. If you leave them in the pond, the dead plants will decompose and cause water quality issues this winter.
While you’re preparing your plants for winter, take some time to do a little clean up around your pond. Remove any dead leaves and foliage, and rake or net out leaves and fallen debris. Water quality matters – even in the winter!
©2014 The Pond Guy Blog. Reproduced with kind permission.

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