Native vegetation refers to plant species that naturally occur and have evolved in a specific region or ecosystem over a long period of time. Plants native to an area are adapted to the local climate, soil conditions, and ecological processes of their native habitat. They play a crucial role in maintaining biodiversity, supporting wildlife habitat, and providing ecosystem services such as soil stabilization, water filtration, and carbon sequestration. In the context of stormwater management, using native vegetation in stormwater facilities can intercept and slow runoff, encourage infiltration, and filter out sediments and soluble pollutants.

Advantages

• Cost-effective
• Drought resistant
• Low maintenance
• Does not require application of fertilizers or pesticides
• Provides a diverse habitat for wildlife

Disadvantages

• Takes longer to establish from seed than turf grass

When selecting native species for stormwater facilities, it’s crucial to account for the site’s climate, hydrology, soil type, sun exposure, road salt, and water retention characteristics. Choose species adapted to specific site conditions and periodic inundation, such as those naturally found in wetlands, riparian zones, or floodplains. Ensure the selected plants can tolerate fluctuating water levels and dry periods common in stormwater systems, such as bioretention basins. Consulting local native plant nurseries, native plant databases, or stormwater management experts can help ensure species selections align with site conditions as well as ecological and functional goals.

Native vegetation may be established from plants (often referred to as “plugs”) or seed. Native plants are available commercially and decrease the time required for establishment by 1 to 2 years, but can increase the initial cost of the practice. Seeding is more economical up front but requires at least 3 years before the plants become established and requires specialized maintenance during that establishment period. Oftentimes, the choice between starting with plugs or seed is dictated by facility type (bioretention basins require plugs) or size (using plugs in large areas becomes cost prohibitive).

However, regardless of the method selected, careful species selection is crucial. Care should be taken to ensure that the plant or seed is sourced locally and is native to the area. Native plant nursery websites usually include information about the native range of the species they offer; often based on the USDA Plants Database and BONAP (Biota of North America Program). County level species distribution maps, based on BONAP, can be found on the North American Plant Atlas (NAPA) website. For stormwater projects in Dane County, species should be selected that are native to Dane County or the surrounding region to ensure ecological compatibility and successful establishment. Information regarding native species selection for projects in the shoreland zone can be found on the acceptable native species page.

Site preparation is crucial before planting native seeds because it creates optimal conditions for successful germination and establishment. Proper preparation reduces competition from existing vegetation, such as invasive or undesirable species, which can outcompete native seedlings for resources like sunlight, water, and nutrients. It also ensures the soil is in the right condition—free of compaction, well-aerated, and with proper nutrient levels—to promote root development and water infiltration. By addressing factors like weed control, soil quality, and drainage before seeding, you improve the likelihood of strong seed-to-soil contact, which is critical for germination. Effective site preparation sets the stage for a healthy, resilient native plant community that supports biodiversity and fulfills its intended ecological or functional role.

Site preparation for native seeding can involve various methods depending on the site's conditions, existing vegetation, and project goals. Mechanical methods, such as mowing, tilling, or disking, can remove existing vegetation and prepare the soil for seeding. Herbicide application is another option, often used to eliminate persistent invasive species or dense sod that might outcompete native plants. Solarization, which involves covering the soil with clear plastic to trap heat and kill weeds, is an effective non-chemical approach for smaller areas. In some cases, smothering with organic materials like cardboard or mulch can suppress unwanted vegetation. For sites with compacted soils, techniques such as aeration or deep tilling may be necessary to improve soil structure and water infiltration. Cover cropping can also be used to outcompete weeds and improve soil health before seeding. The choice of method should consider the specific site conditions, environmental impact, and long-term success of the native planting. Hiring a landscape contractor who specializes in native plants can significantly improve the likelihood of success, as they can select the most suitable site preparation methods and ensure proper follow-up maintenance for successful establishment.

Seed should be applied uniformly following the supplier’s recommendations by broadcast seeding, hydroseeding, or drill seeding. Broadcast seeding involves scattering the seeds on the soil surface by hand or mechanical means and is best utilized on smaller areas and for patching applications. After application, the site should be raked and firmed with a roller or cultipacker. Seeded areas should then be mulched to provide protection for the seed, to reduce the need to irrigate, and to reduce erosion before the vegetation becomes established.

Hydroseeding and drill seeding are more costly than broadcast seeding and are used on larger sites to maximize the application’s cost effectiveness. Hydroseeding, a method that mixes the seed and water together into a slurry, is applied on areas that may be difficult to seed with alternative means. Other amendments, such as tackifiers, polymers, and/or fiber mulch are often added to the slurry, which is sprayed on, to protect the seed and to promote its growth. Drill seeding utilizes a drill or cultipacker seeder to inject the seeds beneath the soil surface. Seeding depth should not exceed 1/8 of an inch. Drilling, while more costly than broadcast or hydroseeding, is generally very effective when performed properly because the seed is protected from wind, water, and wildlife.

To prevent erosion during the seed establishment period, additional management practices are often required. However, due to the slow germination process, the use of heavy erosion blankets and mats is not recommended as the seed may rot. Rather, clean straw mulch that is free of weeds and other seeds may be used. Mulching rates for use with native species differ than those used for non-native species, and it is generally recommended that mulch should be applied at no more than 1 ton per acre.

The use of companion vegetation or cover cropping is also a viable method for controlling erosion during establishment. It provides cover and minimizes weed growth while stabilizing the soil and preventing soil loss. Relatively non-competitive, annual species of vegetation, such as those listed on the Seeding page may be used for this purpose, provided the seeding rate is cut in half. Native plant nurseries that sell seed often also sell seed for cover cropping. Seeded areas should also be inspected after all storm events for evidence of erosion. All necessary repairs should be made immediately.

Planting native plant plugs is an efficient way to quickly establish vegetation in stormwater facilities like bioretention basins. Begin by preparing the site and digging holes slightly larger than the plugs' root balls. Space the plugs appropriately, typically one foot on center for bioretention areas, to encourage rapid coverage and reduce soil erosion. Position each plug so the top of the root ball is level with the soil surface, then gently backfill and firm the soil around it. Water deeply after planting and continue regular watering for the first three to six weeks, the critical establishment period. Once the plants are well-rooted, native vegetation typically thrives without supplemental irrigation, requiring additional water only during periods of extreme drought.

Native vegetation, once well-established, requires little maintenance beyond occasional mowing or periodic prescribed burns and some spot weeding during the growing season. Due to the fact that irrigation and the use of fertilizers, pesticides, and other amendments are unnecessary with native species, long term maintenance costs are generally much less than those associated with non-native species, such as turf grass.

Mowing is necessary during the first 2 years (if establishing by seed) and may be used as an alternative to burning after establishment. Seeded areas should be mowed to a height of 6-12 inches 2-3 times during the first year and once during the second year to prevent weeds from developing seed. Native plants grow slowly at first, and mowing to these heights will cause only minor, if any, damage to these species and allows them access to sunlight. During subsequent years, mowing to a height of 6-12 inches may be performed as an alternative to prescribed burning. Mowing mimics burning by clearing the surface and allowing the sun to warm the soil, without the potential concerns associated with burning.

Prescribed burns can be beneficial every 2-3 years to promote a healthy, diverse landscape and to control the growth of woody species. These controlled burns should only be performed once the vegetation has become established, usually during the third or fourth year. Burning clears away old vegetation and non-native species, leaving a warm, clear area that stimulates new growth. In addition, fire provides nutrients for the growing plants from the ash it leaves behind. Because of the potential for injury and property damage associated with this practice, only trained, experienced professionals should perform prescribed burns.

In addition to periodic burning or mowing, occasional spot weeding is essential to maintain healthy native vegetation. Scheduling weeding sessions at least three times during the growing season—around late May, early July, and early September—helps prevent small infestations of undesirable species from growing into larger, more costly problems. Focus on removing weeds and invasive species that compete with the desired vegetation, as well as clearing away dead plant litter. When weeding by hand, cut weeds as close to or just below the surface to minimize disturbance to the root systems of native plants, avoiding potential damage caused by pulling.

• All grading and tracking shall be completed before seeding begins
• All management practices should be installed and online before seeding
• Maximum seed depth of one eighth of an inch
• To promote growth, seeding should not be performed during excessively wet conditions, as soils may become excessively compacted

Native vegetation can be used in a designed vegetated buffer to trap sediment. Refer to the Buffer Strip page for efficiency information.

Vegetation Management Flyer

Minnesota Plants for Stormwater Design

Wisconsin DNR’s List of Native Plant Nurseries

Identification of Common Wisconsin Weeds

Prairie Moon Nursery – How to Prep Your Site for a Native Seed Mix

Prairie Moon Nursery – How to Hand Sow a Seed Mix

Prairie Moon Nursery – Planting & Care of Potted Plants

Prairie Nursery – Guide to Establishing a Native Seed Mix