Mid-Atlantic Pocket Guide to Water Garden Species

The plants suggested are known to be native in Pennsylvania and the Mid-Atlantic region. They are suggestions only and there are other plants you can select that may better suit your garden site. Before selecting plants for your water garden, or any landscaping project, research the plants you want to use to be sure they suit the site and meet your aesthetic criteria.

Visit the Habittatitude™ website for invasive species information specific to water gardens and aquaria.

Water Gardens

A water garden is fundamentally an outdoor aquarium. The gardener needs to manage the pH, nutrients, and organisms introduced into the system. Just because a plant or animal is invasive doesn't mean it can't be ordered and delivered to your door or purchased locally. Unwelcome hitchhikers may also accompany your purchase. Plants and animals known to be invasive or prohibited in the state are often part of plant orders in the water or plant medium or used for packing.

Prevent Introducing Hitchhikers

• Rinse plants in a light colored bucket of clear tap water until clean
• Dispose of any packing materials or water only after disinfection

Watch for animals or other plant fragments. If it seems likely that the plant has hitchhikers, you can clean emergent types of plants such as arrowhead (Saggitaria spp.). Dip the plant in a 10% chlorine solution, swish it around and shake it off. Rinse in tap water after 30 seconds. This should not be used on submerged plants like Elodea (Elodea canadensis.)

Any hardy non-native plant or animal species may become the next problematic invasive species that can clog our waterways and damage wildlife habitat. In addition, many closely related (same genus) plants can hybridize with the native species, often passing on aggressive traits. Our suggestion is to use native plants whenever possible.

When selecting plants, consider using species native to the region or non-invasive exotic plants. Never use any invasive plant unless it is well outside its hardiness zone, and even then with caution. The USDA plant hardiness zone map is the standard by which gardeners can determine which plants are most likely to thrive at a location. Pennsylvania ranges in hardiness zones from 5a in north central to 7b in southeastern and southwestern regions. Choose a reputable nursery, ask if the vendor is aware of regional or federal restrictions and verify the scientific names are correct. Common names may be used for several different species, not all of which are harmless.

Notes on Snails and Fish

Snails, by their nature, are generally easily moved or move themselves under moist conditions. They are often intermediate hosts for parasites. Snails have a large appetite for vegetation that we don't necessarily want eaten. For this reason their use in water gardens is not recommended.

Fish are sometimes added to water gardens for visual interest. Keep in mind that they will add nutrients to the system that you will have to remove with filters or balance using plants. The fish commonly used in water gardens are goldfish and koi, both of which are carp from Asia. They should never be released or allowed to escape into local waters. They consume aquatic plants and can make the water cloudy as they feed. Carp will also grow quite large, sometimes outgrowing their space.

"If you build it, they will come..."

Fish may also be an attractant to birds that consider expensive koi a tasty snack and can move those snails on plant material or in their digestive systems. Local amphibians such as frogs, toads or salamanders may decide your water garden is a good place to reproduce or hang out. Fish are competitors that eat their eggs. Local turtles may also move in to your water feature and birds and butterflies will come for a drink. Rather than investing in exotic animals, rely on the locals to move in.

Invasive Species

Any hardy non-native plant or animal species may become the next problematic invasive species that can clog our waterways and damage wildlife habitat. In addition, many closely related (same genus) plants can hybridize with the native species, often passing on aggressive traits. Our suggestion is to use native plants whenever possible.

When selecting plants, consider using species native to the region or non-invasive exotic plants. Never use any invasive plant unless it is well outside its hardiness zone, and even then with caution.

The USDA plant hardiness zone map is the standard by which gardeners can determine which plants are most likely to thrive at a location. Pennsylvania ranges in hardiness zones from 5a in north central to 7b in southeastern and southwestern regions.

Choose a reputable nursery, ask if the vendor is aware of regional or federal restrictions and verify the scientific names are correct. Common names may be used for several different species, not all of which are harmless.

Invasive Plants

Invasive Snails and Fish

Web Resources

• Plant Hardiness Zone Map. United States Department of Agriculture (USDA)
• USDA PLANTS database. Check a garden addition for being native or introduced in your state.
• Nonindigenous Aquatic Species Database. United States Geological Survey (USGS)
• Invasive Plants. United States National Arboretum
• Habitattitude™

Other Resources

Rhoads AF & Block TA. 2011. Aquatic Plants of Pennsylvania, University of Pennsylvania Press, Philadelphia PA, 308 pp.

Rhoads AF & Block TA. 2007. The Plants of Pennsylvania, 2nd Edition, University of Pennsylvania Press, Philadelphia PA, 1042 pp.

Photo Credits

Butomus umbellatus - Flowering spikerush, RAHoward- R.A. Howard. ©Smithsonian Institution. Courtesy of Smithsonian Institution, Richard A. Howard Photograph Collection

Carassius auratus - Goldfish, Duane Raver, US Fish and Wildlife Service, Bugwood.org

Ceratophyllum demersum - Coontail, Vic Ramey, IFLAS, University of Florida

Cyprinus carpio - Koi, Stan Shebs, Wikipedia Commons

Eliocharis palustris - Spikerush, Jennifer Anderson @ USDA-NRCS PLANTS Database

Egeria densa - Brazilian egeria, Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org

Eichhornia azurea - Anchored water hyacinth, Kurt Stueber, Max-Planck-Institute for Plant Breeding Research, Cologne, Bugwood.org

Eichhornia crassipes - Water hyacinth, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Elodea canadensis - Elodea, Dana Rizzo, Penn State University

Hydrocharis morsus-ranae - Common frogbit, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Hydrilla verticillata - Hydrilla, Chris Evans, River to River CWMA, Bugwood.org

Ipomea aquatica - Swamp morning glory, Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org swamp

Iris versicolor - Blueflag iris, Jennifer Anderson @ USDA-NRCS PLANTS Database

Iris pseudacorus - Yellowflag iris, Nancy Loewenstein, Auburn University, Bugwood.org

Justicia americana - Water-willow, Larry Allain @ USDA-NRCS PLANTS Database

Lagarosiphon major - Oxygen weed, Rohan Wells, National Institute of Water and Atmospheric Research, Bugwood.org

Ludwigia peruviana - Primrose-willow, Amy Ferriter, State of Idaho, Bugwood.org

Lythrum salicaria - Purple loosestrife, John D. Byrd, Mississippi State University, Bugwood.org

Myriophyllum aquaticum - Parrotfeather, John M. Randall, The Nature Conservancy, Bugwood.org

Myriophyllum spicatum - Eurasian watermilfoil, Barry Rice, sarracenia.com, Bugwood.org

Notemigonius crysoleucas - Golden shiner, Uland Thomas, NANFA.org

Nuphar lutea - Spatterdock, Bryan Swistock, Penn State University

Nymphoides peltata - Yellow floatingheart, David Cappaert, Michigan State University, Bugwood.org

Nymphaea odorata - Fragrant water lily, Joseph Dougherty, ecophotog@yahoo.com

Pistia stratiotes - Waterlettuce, Troy Evans, Great Smoky Mountains National Park, Bugwood.org

Pimephales promelas - Fathead Minnow, Rosy-red strain, Wikipedia Commons

Pontederia cordata - Pickerelweed, Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database

Salvinia molesta - Giant salvinia, Larry Allain @ USDA-NRCS PLANTS Database

Trapa natans - Water-chestnut, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Reviewers

Prepared by Diane Oleson, natural resources extension educator in York County

The author wishes to thank the following individuals who served as reviewers for versions of this publication:

• Susan M. Boser, water quality extension educator in Beaver County
• Thomas Mc Carty, water quality extension educator in Cumberland County
• Bryan Swistock, water resources extension associate
• Dana Rizzo, water quality extension educator in Westmoreland County
• Sarah Whitney, associate director, Susquehanna River Watershed, Pennsylvania Sea Grant