Cynwyd Station bed
2021 redesign plan
In the spring of 2021, the Friends contracted with landscape designer Orsolya Lazar to design and install a renovation to the perennial bed at the Cynwyd Station.
This bed had been through a couple iterations over the years. The most recent plan we had access to was from 2012. While some of the things planted then had done well--Prunus laurocerasus (cherry laurel), Miscanthus sinensis (Chinese silvergrass), and Panicum virgatum (switchgrass)--others were not visible. A number of weedy things had also moved in--e.g. crown vetch (non-native) and dogbane (a native relative of milkweeds).
Plant palette for the redesign
Several criteria were used in determining the redesign priorities. We asked for a sustainable design, meaning one with plants that would not require frequent dividing or other maintenance. Use of native plants was requested, with a focus on plants that provide ecosystem services such as nectar for pollinators and seeds for animals to eat. However, in the interests of sustainability, we did not remove most of the non-native (but non-invasive) plants that had thrived in the site. Even non-native plants provide ecosystem services. Another aspect of sustainability is making the site conditions a primary factor in plant selection. This bed is an island in a sea of concrete and much of it is quite steeply sloped and therefore quite dry and hot in the summer. It gets considerable sun. Thus, much of the site is suitable for popular prairie natives, and they predominate in the list of material recommended (listed here).
Maintenance plan
Given that this bed (as well as other land along the trail) is largely maintained by volunteers, an important part of the design was a yearly management plan. While some of our volunteers have extensive horticultural experience, many do not, and the corps of volunteers changes over time. We requested a maintenance plan detailed enough to keep the bed healthy but one that also took into account the sustainability priorities--no mulching, minimal watering, etc.
The excerpts below should give a flavor of the management strategies we are attempting to adopt not just here but in other areas of the trail as well.
General guidelines
Minimize soil disturbance, only dig plants if necessary for control for rhizomatous species. Avoid compacting soil by stepping on it. As much of the maintenance as possible should be done from outside the bed. Natural processes, plants spreading should be allowed and encouraged if they do not interfere with main goals. Switchgrass should be limited to three distinct areas located in the center of the bed furthest from the walkway. More vigorous species like asters, goldenrods will need to be limited to their designated areas, so they do not reduce diversity over time.
Tasks
Cutting back and mulching:
Cut perennials back in late March-early April to 3-6 inches. Best to do it when plant material is dry and when stalks can be cut or broken into 2-4 in sections and used to mulch the planting bed. This will cover any bare soil, help control weeds, minimize erosion and provide nutrient and organic matter to the soil. No additional amendment is necessary. Cut stems also provide habitat for wildlife. If excessive amount of material (over 1 inch thick as mulch) is present it can be used to mulch other planting areas.
* A second cutting in mid to late-June can be done to reduce the height of late blooming tall perennials, like New England and aromatic asters, ‘Solar Cascade’ and stiff goldenrods. Trim 1/3 to 1/2 of the shoots with a sharp soil knife, small hand shears or hedge shears. This second cutting can help control the height of late blooming perennials and promote denser growth.
Control weeds by cutting right at or above the soil surface during dry weather when possible and before seeds are set. If seeds are not present, stalks can be left around desired plants to act as mulch. Reduce soil disturbance as much as possible and only dig up rhizomatous weeds or vines that are too large to control with cutting only. Small, annual, non-invasive weed species (chickweed, bittercress, etc.) will likely get outcompeted by larger, more robust plants and can be left as place holders. Tall, perennial weeds without rhizomes can be controlled with repeated cutting at soil level or by carefully pulling roots up if it can be done without harming nearby plants. Japanese stiltgrass is an annual invasive and should be pulled in late summer to prevent seed production. Plants with rhizomes could be controlled with a combination of repeated cutting, removal of rhizome and if needed, spot herbicide application by a licensed professional.
Watering
Water infrequently, only when necessary, during periods of drought. Make sure water is soaking into the soil 3-4 inches deep. New plants during the first year of establishment might need watering occasionally. From second year on plants rarely need watering except during severe drought with weeks without rain. Frequent, shallow watering encourages weed growth and is not recommended.
Fertilizer and other soil amendments
Most native plants in this planting are adapted to dry, lean soil. Fertilizer and soil amendments should not be applied unless necessary based on soil test results. A soil test was performed in spring of 2021 to find the cause for chlorosis of the inkberries. The soil pH was 7.4, higher than the 6.8 or below, recommended for inkberries. Sulfur was applied. Repeat applications once or twice a year as needed to lower the pH to 6.8 or below based. Testing the soil pH periodically is recommended, especially if leaves are chlorotic.