Preparing Aquatic & Pond Plants for Winter in New Brunswick

August 1, 2025

Here in New Brunswick, we know winter doesn’t mess around. By the time late fall rolls around, most ponds are frozen solid on top, and that can be tough on the plants that made your pond so lively all summer long. The good news? With just a little prep, you can help your aquatic plants survive the cold — or bring them inside so you can enjoy them again next year.

Whether you’re a first-time pond owner or a seasoned gardener, winterizing your pond plants isn’t complicated. It’s all about knowing which plants can tough it out in the ice and which ones need a little extra care. Let’s walk through it together.

Why Aquatic Plants Need Winter Prep

New Brunswick winters are long and cold, and ponds often freeze down 12–18 inches (sometimes deeper). That’s no problem for hardy plants if they’re tucked below the ice, but it’s a death sentence for tropicals left outdoors.

Here’s the key difference:

Hardy aquatic plants (like cattails, iris, water lilies, and rushes) can handle dormancy under ice, as long as their roots or rhizomes don’t freeze solid.
Tender/tropical plants (like papyrus, taro, water hyacinth, and water poppy) will turn to mush after the first frost.

Taking time to sort and prep your plants now means:

A healthier, clearer pond come spring.
Less algae from decaying plant matter.
Better survival for fish and other pond life.

Preparing Hardy Aquatic Plants for Winter

Most of the perennials you’ve planted in your pond can survive our winters with the right treatment.

Water Lilies (hardy types):

Trim away yellowing leaves and spent flowers, but leave the crown untouched.

Sink the pot into the deepest part of your pond so it sits well below the freeze line.

Cattails, Rushes, Arrowhead, and Iris:

Cut dead foliage down to about 4–6 inches above the crown.

Submerge containers deeper in the pond.

For wildlife lovers, consider leaving some stems standing — they provide habitat for insects and winter interest for birds.

Marginal/Bog Plants (marsh marigold, water forget-me-not, lizard’s tail):

These can stay in shallower zones if the crown is insulated.

In really exposed spots, mulch around boggy edges.

Floating Hardies (duckweed, elodea, hornwort):

These usually survive under the ice and can even provide food and oxygen for fish over the winter.

Preparing Tender/Tropical Aquatic Plants

Some of the real showstoppers of summer ponds are tropicals — and sadly, they can’t survive outside here. You’ve got two choices: overwinter them indoors or treat them as annuals and replace them each spring.

Papyrus & Taro:

Lift and store their tubers/rhizomes much like you would cannas or dahlias.

Keep in a cool (10–15°C), dark space in slightly damp peat moss, OR grow them as houseplants in shallow water trays near a sunny window.

Water Hyacinth & Water Lettuce:

These won’t survive a frost outdoors.

To keep them, set them up indoors in an aquarium or tub under grow lights.

Many gardeners simply compost them and buy fresh in spring.

Water Poppy & Pennywort:

It can be kept alive in aquariums or even in a sunny windowsill container.

Other Tender Favourites (Botswana Wonder, Bloody Dock, Houttuynia):

Bring indoors as container plants and keep the soil moist.

Common Mistakes to Avoid

Even experienced pond keepers can slip up when winter prep time rolls around. Watch out for these pitfalls:

Leaving tropicals outside – they will be gone after the first hard frost.

Cutting too low on hardy plants – don’t cut into or below the crown.

Ignoring decaying foliage – it breaks down and feeds algae in spring.

Forgetting oxygen – a fully frozen pond traps gases; fish and plants suffer.

Waiting too long – once frost hits hard, it’s harder to save tender plants.

Tips & Tricks From Our Experts

Here are some insider tips we share with customers who want the smoothest spring comeback possible:

Start cleanup when nights are consistently below 10°C.

Use the tier method: hardy plants go down to the deepest pond tier, below the freeze line.

Take a few cuttings (like pennywort or water celery) and root them indoors in jars — easy insurance for next season.

Store tender rhizomes wrapped in damp peat moss in a cool basement.

Consider a small floating de-icer or aerator to keep one spot of the pond ice-free for gas exchange.

General Pond Prep Extras

Winterizing your plants is just one piece of the puzzle. A few pond-wide steps now can save you big headaches later:

🍂 Leaf netting: Catch falling leaves before they sink and rot.

💧 Pumps & filters: Remove and clean unless they’re designed for winter use.

🐟 Fish care: Stop feeding when water temps stay below 10°C — their digestion slows way down.

❄️ Ice safety: Never smash pond ice — use a floating heater or de-icer instead.

Winter doesn’t have to mean the end of your pond’s beauty — it just means giving your plants the right care at the right time. Hardy plants can sleep peacefully under the ice, tropicals can be brought inside for another season, and your pond will thank you in the spring with clear water and healthy growth.

Think of winter prep as a reset button. With a little effort now, you’ll set yourself up for an easier, more rewarding pond season next year.

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