water garden

This autumn has had some unseasonably warm days, but winter is right around the corner, which means you need to prepare your water garden for the coldest months. Before winter hits, you should protect plants, fish and wildlife by winterizing your water garden to ensure it remains healthy for the spring season.

Protect Your Plants

Can your plants survive through the winter? That depends on what hardiness zone you live in. If you are unsure of what plants are considered hardy in your area, first check the USDA Plant Hardiness Zone Map to determine in which zone your garden is located. Then, cross-reference information about your garden plants so that you know what kind of care they need based on your hardiness zone. 

Tips for Illinois and Indiana: Illinois falls in zones 5a-7a and Indiana lies in zones 5b-6b. Some winter hardy plants recommended for water gardens in these regions are American yellow lotus (hardy in zones 4-11), common arrowhead (hardy in zones 5-10) and American water willow (hardy in zones 4-11). 

If your pond is deep enough, keep winter-hardy plants under at least two feet of water. Plants that are not winter-hardy should be in heated ponds or tubs above 50° F. Oxygenators (e.g., hornwort, American waterweed, sago pondweed) or floating plants should be moved into indoor aquariums.

For the adventurous, you can try overwintering your water garden plants indoors in a variety of ways, either keeping them cool and dormant or active as houseplants.

Clean Your Pond

A clean pond is a happy pond. Remove any decomposing plants and debris from your water garden. If the leaves haven’t fallen in your area yet, erect a net over the water to catch leaves before they enter the pond. Thin out any dense vegetation or cut back plants you plan to overwinter in the pond.

You can compost many unwanted water garden plants, but some should not be composted. Invasive plants should be bagged in plastic and placed in the trash because if seeds, roots or other parts are not fully decomposed, then they can spread to new areas. If there are snails living in your water garden, avoid composting any plants from the pond.

Another option is to donate or trade unwanted plants with other water garden hobbyists. However, some plants are invasive and may be prohibited for sale, trade or transportation in your state. Visit takeAIM.org/regulations for a list of state and federally prohibited species.

Remember that releasing aquatic plants in natural areas assuming that they are native or harmless can spread invasive species. Invasive plants and animals cost millions in tax dollars to control and are sometimes impossible to remove. Visit ReleaseZero.org to learn how to Be A Hero – Release Zero and keep ecosystems and wildlife healthy.

Be A Hero - Release Zero campaign logo over photo of lake covered in invasive plants. There is a floating dock and trees in the background.

 

This advice was adapted from: 
Winterizing the water garden – Virginia Cooperative Extension
Prepare your water garden for winter responsibly – Michigan State University Extension 
Avoid spreading aquatic invasive species when winterizing your water garden – Michigan State University Extension 

Contacts:
Greg Hitzroth, hitzroth@illinois.edu
Amanda Huegelmann, amandah@illinois.edu

Reviewers:
Richard Harper, Aquatic Maintenance
Rich Heimberger, Healthy Pond
Martha Smith, University of Illinois Extension


Illinois-Indiana Sea Grant is a part of University of Illinois Extension and Purdue Extension.

IISG Instagram

Ready for a party? Join us on the newly-expanded Wild Mile for a celebration of our urban waterways and thriving park spaces. Enjoy local beer, food trucks, and an outdoorsy prize drawing while learning about local environmental nonprofits and volunteer opportunities! This event is free and fun for all ages!The block party is rain-or-shine, and we'll only cancel in the case of hazardous weather!This year’s community partners include @Openlands, Current Water, @chicago_enviro, @cleanupclub_chicago, @chicago_birder, Blazing Star School, @cubillinois, Friends of the Bloomingdale Trail, @chicagoshapers, @reducewastechicago, Southern Utah Wilderness Alliance, and @honeycombproject!Learn more at the link in bio.
📢 Show Your Support for Sea Grant! 📢Continued federal funding for Sea Grant in FY26 is crucial, and we need your help to demonstrate the nationwide support for these essential programs.🖊️ Sign the letter urging Congress to continue funding Illinois-Indiana Sea Grant and all 34 state Sea Grant programs:🔗 https://forms.gle/7sPGHGyh8j8a7vfGA or link in bio
Exciting news! The call for sessions for the 2026 Emerging Contaminants in the Environment Conference has been extended! We are excited to offer the opportunity to propose a speaker or panel session during the 2026 Emerging Contaminants in the Environment Conference April 28-29.  The conference will feature traditional 15-minute presentations and a poster session on the latest in emerging contaminant research, policies, and outreach in the soil, water, and air.The deadline to propose a session is September 30, 2025.Learn more at go.illinois.edu/ecec or the link in bio
Stay safe and have fun this Fourth of July with these 5 water safety tips! Click the link in bio to learn more ways to keep yourself and others safe as you enjoy the Lake Michigan beaches this holiday.
Skip to content