Native Plants: Ecology, Cultivation, and Township Ordinances

At the 2 September 2025 #NewtownPA Planning Commission meeting, Kim Flanders, a registered landscape architect with CKS Engineers, gave a presentation focused on a revised landscape ordinance for Newtown Township, specifically the new requirement for 100% native plants in development projects. Listen to this “Mack’s Deep Dive” podcast based on a recording of her comments:

Q&A

The following list of questions and answers was prepared by Google’s NotebookLM AI program based on Ms. Flander’s presentation.

What is a native plant?

A native plant is defined as a species that has evolved in a specific location over a long period, developing complex relationships with its environment and other organisms within that ecological community. More specifically, for Pennsylvania and the northeastern United States, it refers to plant species that existed naturally in the region prior to European settlement. This definition emphasizes the deep historical and ecological connections of these plants to their local ecosystem, distinguishing them from introduced or adapted species.

How do native plants benefit wildlife and the ecosystem?

Native plants are crucial for wildlife, especially insects, which often have an evolutionary history with specific native plant species. For example, monarch butterflies can only lay their eggs on milkweed. Many native bee species time their life cycles to the blooming periods of particular native plants, relying on their specific pollen to feed their larvae. This interconnectedness forms the base of the food web, as birds need insects to survive, and insects, in turn, depend on native plants. Planting native species therefore supports a diverse and healthy local ecosystem.

Are native plants easier to grow and maintain?

While native plants are adapted to local soil and climate conditions, and can be less work if planted correctly, they are not necessarily "easier" to grow in all circumstances. The principle of "right plant, right place" is crucial; factors like soil type, drainage, slope, sunlight, and nearby plant communities must be considered for successful growth. Urbanized conditions, such as those found in parking lot islands or areas with altered stormwater flow, can make it difficult to replicate the ideal native environment, potentially stressing even native trees. Additionally, some native shrubs can be aggressive and spread without proper maintenance, and native plants are not immune to diseases or pests.

What are cultivars and hybrids, and are they considered native?

Cultivars and hybrids are plant varieties that have been bred or selected for specific traits, often ornamental ones like leaf form or flower color. A cultivar's name often includes a word in quotes after the Latin name (e.g., "Red Sunset" Red Maple). While they originate from native species, research is ongoing to determine if these ornamental changes affect how wildlife, especially pollinators, use them and if they provide the same ecological benefits as straight native species. The proposed ordinance allows for some cultivars and hybrids to be included in approved plant lists, particularly those that offer benefits like disease resistance (e.g., Dutch Elm disease-resistant elms) or adaptability to changing climates.

What challenges arise when incorporating native plants into urban development, such as parking lots?

Urban development poses several challenges for native plants. Many native shade tree species, for instance, do not grow well in the harsh conditions of parking lot islands due to factors like heat, compacted soil, and limited space. Urbanization alters natural drainage and soil conditions, making it difficult to replicate the specific growing environments many natives prefer. Additionally, ensuring sufficient space for root systems to prevent damage to infrastructure like sidewalks and utility lines is a concern, as native trees, like maples, can have aggressive surface roots. Developers are now being encouraged to consider wider planting areas and choose species appropriate for the specific conditions of urban settings.

How does the proposed ordinance address the need for plant diversity?

The updated ordinance incorporates recommendations to increase plant diversity within developments. Historically, areas were often planted with a single species (e.g., 100 ash trees along a street). This practice proved disastrous when diseases like the Emerald Ash Borer decimated entire tree populations. By requiring diversity, the ordinance aims to mitigate the impact of disease outbreaks, ensuring that if one species is affected, the entire tree line is not lost. This approach enhances the resilience of urban plantings and contributes to healthier ecosystems.

What is the process for updating and enforcing the native plant ordinance?

The Board of Supervisors has expressed interest in revisions to the existing landscape ordinance to require 100% native plants in developments. The proposed changes, presented in a red-lined version, include an approved plant list. If a designer wishes to use a non-native plant, they must submit a waiver request, providing a specific reason for the deviation. This reason will be reviewed by a professional, such as a registered landscape architect (RLA). The ordinance also includes provisions for maintaining plantings post-development, though enforcement can be challenging. The plant list is expected to be updated periodically (e.g., every five years) to reflect new information on plant adaptability, invasive species, and availability.

Where can one find reliable lists of native plants for their region?

While there isn't one single, universally perfect list, several resources can serve as a starting point. State agencies like the DCNR (Department of Conservation and Natural Resources) provide lists, often highlighting invasive plants and recommending native alternatives. However, it's crucial to consider the specific "microclimate" of a site, as what thrives in one part of Pennsylvania might not do as well in another, more mountainous or drier region. Consulting local professionals or updated resources like specialized books can also be beneficial, as plant lists need constant revision due to environmental changes and evolving understanding of native ecology.

Posted on 03 Sep 2025, 10:38 - Category: Ordinances