Learn How To Landscape Responsibly

Penn State offers sustainability classes to build skills

By Margaret Pickoff

In many parts of the country, fall and spring typically deliver lots of rain. The fate of all that rainwater depends on the surface where the rain happens to fall. Porous or permeable surfaces like soil allow water to infiltrate an aquifer, where it’s stored as groundwater. But when rain falls on hard, impermeable surfaces—parking lots, roads, and sidewalks—it runs off and collects downhill at the lowest point. In the best-case scenario, the water runs into a municipal storm sewer, where it can be treated and re-used. But during a heavy storm, storm systems can become overwhelmed or clogged with debris and stop functioning, which can lead to dangerous flooding and pollution of waterways and drinking water.

Ruth Benner, Penn State

The way landscapes are designed and maintained has a big impact on mitigating many destructive stormwater scenarios. A new online course from Penn State Extension, Plant Identification and Usage: Plants for Green Infrastructure, focuses on plant selection, design, installation, and maintenance of green-infrastructure projects. These projects can include landscape features like rain gardens, green roofs, and riparian buffers, each of which is designed to reduce stormwater runoff, prevent flooding, and keep pollutants from entering bodies of water. Other elements of green infrastructure may include rain barrels, which collect and store rainwater from roof surfaces, and permeable pavers for sidewalks, driveways, and patios, which are made of materials that allow water to infiltrate the soil rather than run off.

Many municipalities have regulations in place regarding stormwater management, which may require or reward the use of green infrastructure in new development. In addition, parks, public institutions, and private-property owners are increasingly seeking to integrate green-infrastructure elements as part of a shift to more sustainable landscaping practices.

Rain gardens are some of the most basic and commonly utilized green-infrastructure projects in the landscape. They are shallow, bowl-shaped gardens that collect stormwater and either allow it to soak into the ground or be taken up by plant roots. Like ornamental gardens, rain gardens can be planted with design in mind; utilizing a variety of woody shrubs, small trees, ornamental grasses, and flowering perennials can make them an attractive addition to the landscape. And since they are often planted with native plants, rain gardens can also create enhanced wildlife habitat and resources for pollinators on the property.

One common misconception about rain gardens is they are always wet or waterlogged, like a shallow pond or miniature wetland. Most of the time, rain gardens should be about as dry as any other garden on the property. They may hold water for a short period of time after a heavy rain, but properly sited and installed rain gardens should fully drain within 48 hours. Before installation, it helps to conduct a soil-percolation test to make sure the drainage is adequate at the site. This can be done by digging a 1-foot-deep hole, filling it with water, and using a timer to measure how long it takes for the water to drain. If the hole drains in less than six hours, the site is ideal.

Do It Right

Once a site is deemed appropriate, installation can begin. A few days prior to digging, any buried utility lines should be marked to avoid costly damage to electric, water, and gas lines. Marking paint or rope can be used to mark the shape of the rain gardens. Rain gardens can be any shape, but many are created with curved edges for a more organic look. The deepest part of a garden (near the center) should be 6 to 8 inches. The depth should taper around the sides to create a bowl shape.

Proper plant selection for rain gardens is vital to the health and function of the system. Because the soil in rain gardens alternates between wet and dry, they need to be planted with species that can tolerate both intermittent flooding and periods of dry soil. The plants that do best in rain gardens are those that are naturally found on riverbanks, pond edges, and areas that receive periodic flooding. Some examples of woody plants that fall into this category are buttonbush, winterberry, river birch, pawpaw, and serviceberry. Native perennials, like great blue lobelia, swamp milkweed, blue flag iris, golden ragwort, and New England aster, can also withstand the wet-dry fluctuations of rain gardens, while adding a colorful floral display.

Connie Schmotzer, Penn State

Plants for rain gardens can be sourced from a nursery as plugs or finished plants. Plugs are young plants raised in small, individual cells that can be purchased at a relatively low price. Because of their size, they are quick to plant and adapt easily to on-site soil conditions. Finished plants are larger and more mature, and tend to be more expensive. Planting these takes longer because the planting holes are larger, and the plants will require more frequent, deeper watering during establishment due to their more-developed root systems.

Rain gardens require ongoing maintenance to keep them healthy, lush, and working properly. While the plants are establishing, gardens should receive about 1 inch of water per week. If the property experiences periods of drought, supplemental irrigation may be necessary. As plants in the gardens mature, it’s important to keep weeds at bay, which can be done through a combination of hand-pulling and mulching. Should any of the plants die, they should be replaced as soon as possible in order to prevent weeds from colonizing the open space. After storm events, any sediment and debris that accumulates should be removed and the gardens should be checked so they are still draining properly. Cutting back perennials and compost dead vegetation each spring gives plants a boost as they begin growing again.

Take A Class

Incorporating green infrastructure into your next landscape project should be considered. Rain gardens are just one example of the types of projects that can help property managers and parks professionals manage stormwater before it poses a flooding hazard. Green roofs, rain barrels, bioswales, and permeable pavers can be integrated into existing park infrastructure relatively simply. These projects can also serve as educational attractions; when installed alongside interpretive signage, homeowners and other park visitors may be encouraged to incorporate green infrastructure into their own landscapes.

Green-industry professionals, landscape-business owners, and those seeking employment in landscape installation and maintenance can build crucial green-industry skills through a new series of self-paced, online courses from Penn State Extension. In addition to green infrastructure, course topics in the series include herbaceous perennials, shade trees, native plants, residential-landscape design, landscape safety, and Employee Landscape Training courses that provide basic skills for those who are new to landscaping. Each course takes between one and three hours to complete, and includes educational videos, images, short readings, and knowledge check questions to keep learners on track. Each section of the course ends with a short quiz. The price per course ranges from $19 to $59. For a full list of available courses, visit: https://extension.psu.edu/train-your-landscape-crew-and-save.

Margaret Pickoff is a Horticulture Educator for Penn State Extension. Reach her at (267) 483-2026, or mfp5667@psu.edu.