The fundamental principle for the environmentally sound management of landscapes is “choose the right plant, in the right place.” Ideal landscape plants are native and adapted specifically to the soil, degree and direction of slopes, precipitation type and amounts, wind direction and speed, light patterns, and microclimate. Susceptibility to major damage by insects and other pests is another selection criterion, as are the nutrient levels of the area. By using native or adapted plants that mimic natural ecosystems, landscapes that are designed for the specific location, management capabilities and desired style can reduce overall management inputs, attract pollinators, provide multi-season interest, and enhance out-of-play areas.
13.1 Planning and Design
Planning begins with a careful assessment of existing conditions. Slopes and drainage patterns impact not only the playability of the course, but the survival of existing and proposed plants. A majority of the non-play areas on the golf course should remain in natural cover. Supplemental planting of native or adapted trees, shrubs, and herbaceous vegetation can enhance the habitat of wildlife, including non-game species, birds, and pollinators, in non-play natural areas. Supplemental planting can also limit soil erosion and protect stream banks. Mimicking natural ecosystems by leaving dead trees (snags), brushy understory plants, and native grasses and forbs in these areas also reduces maintenance work by minimizing or eliminating the need to mow or apply fertilizer or pesticide.
Designs for higher-impact, higher-use landscape areas, such as around the clubhouse, should utilize natural drainage patterns and channel runoff away from impervious surfaces (e.g. paved areas), conserve water, and lower the nutritional input requirements once mature. Installing rain gardens in locations where they catch and temporarily hold water (such as near roofs and other impervious surfaces) helps control stormwater runoff, remove contaminants before releasing water into the surrounding soil or aquifer, and conserve water by reducing supplemental irrigation needs. For more information on rain gardens, see the University of Delaware Cooperative Extension publication Rain Gardens.
Golf courses are excellent facilities for zoning the landscape with designations of high-impact zones, transition zones, and perimeter zones, and for matching high-use and high-impact areas to plants and landscape styles that need more intense management.
13.1.1 High-use and High-impact Zones
In high-use and high-impact zones, the design intent is to create highly ornamental, garden-like landscapes based primarily on visual impact and functionality, not necessarily related to the colors, patterns, and cycles of the native Delaware landscape. If site conditions are suitable and aesthetic requirements are met, regional flora should be given preference. There will be an elevated level of intervention and maintenance, sufficient to create and maintain a highly ordered aesthetic attractive on a small to medium scale, and evident even when viewed at close range. Such designs rely on well-defined groupings and masses to create ornamental impact based upon qualities of color, texture, and form. This approach is appropriate for small- to medium-scale sites where the desire for a neat, highly ornamental appearance exceeds the capacity of the native and regional flora, and/or where the cultural conditions on the site are so heavily affected they severely limit the choice of native or regional species. It is appropriate in areas where the Delaware native flora is a minimal or nonexistent part of the local context. Well-defined, small-scale, high-visibility sites such as the clubhouse landscape and parking lot traffic islands are examples of high-use and high-impact zones. In such zones, these steps are recommended:
- Remove existing vegetation completely, expect for desirable specimens, which may be retained.
- Correct and maintain environmental conditions to facilitate plant growth. Such changes may include tillage, soil amendment, soil replacement, or modification of topography and drainage.
- Select the plant palette for multiple seasons of interest, resulting in plantings that are neat and attractive on a small scale.
- Select plants based on their ability to survive drought, full sun, wind, salt, or other cultural extremes as much as possible within the design parameters.
- Invest more in plant material to create immediate impact.
- Weed routinely.
- Provide supplemental watering whenever conditions would negatively impact the visual effectiveness of the planting.
- Use mulch as a typical ground layer.
13.1.2 Transition Zones
The design intent in transition zones features ornamental landscapes inspired by the regional colors, patterns, and cycles of the native Delaware landscape, but is not necessarily based on plant community dynamics. These areas require a moderate level of intervention, sufficient to create and maintain an aesthetic order that is noticeable and attractive on a medium to large scale. The designs rely on well-defined groupings and masses to create ornamental impact, using regional plant associations when practical to suit this purpose.
This approach is appropriate for medium- to large-scale sites where cultural conditions are suitable, or suitable with moderate modifications, for a mix of Delaware and North American native species. This approach also works for moderate installation and maintenance budgets. It is appropriate in areas where the Delaware native flora is a modest to minimal part of the local context. Transition zone landscaping may occur on the course at tees or key junctions of paths. Creating transition zones can include these steps:
- Selectively or completely remove existing vegetation. In some cases, the existing vegetation can be left as the ground layer.
- Correct and maintain environmental conditions to facilitate plant growth, which may include soil modifications (e.g. change pH).
- Select the plant palette for multiple seasons of interest that match regional cycles, organized on a medium to large scale.
- Restrict plants to species that tolerate drought, full sun, wind, salt, or other cultural extremes.
- Spot control aggressive weeds on a regular basis to supplement plant competition as the primary method of weed control.
- Provide supplemental watering during establishment and only in extreme drought conditions.
- Use mulch around planted specimens as needed, but the long-term ground layer will develop from seeded, planted, or existing vegetation.
13.1.3 Perimeter Zones
The design intent is to develop attractive, naturalistic landscapes based directly on the regional ecology: the dynamics, patterns, colors, and cycles of Delaware’s native plant communities. A minimal level of intervention is required for these areas, just sufficient enough to create and maintain an aesthetic order that can be appreciated on a large scale. Though not intended to fully replicate native plant communities, regional plant associations and dynamics are conserved and enhanced. The low level of intervention allows for considerable natural growth and propagation of native plant species on site.
This approach is appropriate for large-scale sites where cultural conditions are suitable, or suitable with minor modification, for Delaware native species, and where the installation and maintenance budget is minimal. It is particularly appropriate in areas where the Delaware native flora remains a significant part of the local context. This perimeter zone approach should be used in landscaped areas throughout the remainder of the course. Here are key steps to take in perimeter zones:
- Selectively remove existing vegetation to introduce aesthetic order or remove highly undesirable species. The existing vegetation is rarely completely removed.
- Only minimal modifications of environmental conditions are employed. Topography may be modified to provide sites conducive the growth of regional vegetation.
- Select the plant palette to complement the surrounding vegetation in terms of patterns, color, and cycles. Select plants based in their likelihood to thrive in the existing conditions, with an understanding and awareness of site ecology and opportunities provided by cultural niches.
- Restrict plant selection to species that tolerate drought, full sun, wind, salt, or other cultural extremes.
- Plant competition from desirable species is the primary method of weed control, but spot control of aggressive species that threaten the long-term survival of the site is also practiced.
- Provide supplemental watering during establishment only.
- Use mulch around planted specimens as needed, but the long-term ground layer will develop from seeded, planted, or existing vegetation.
13.2 Site Inventory and Assessment
Before developing a landscape plan, conduct an inventory of existing plants, their condition and quality, their contribution to the overall style of the course, and how they’ve been managed. For landscaped areas, conduct a soil analysis and a soil test. The soil analysis evaluates the structure and texture of the soil. If needed, soil amendments can improve the structure and texture of soil, increase its water-holding capacity, and reduce nutrient leaching. Soil amendments, such as landscape waste compost, can contribute to an overall healthier plant environment, allowing easier root development and fewer soil-related problems. Do not use peat moss as an amendment as it is both expensive and originates from peat bogs, which are non-renewable. Apply fertilizers based on the results of a soil test as described in the “Nutrient Management” section.
13.3 Plant Selection
Select plants for landscape planting that grow in natural ecosystems in the area, especially in the perimeter zones and out-of-play areas (see zone descriptions in Section 13.1). Native plants provide food and cover for native insects, birds, and other game and non-game wildlife. As land becomes developed, it is even more important to provide habitat and other ecosystem services (fresh water, clean air, carbon sequestration, etc.) in open, managed areas like golf courses. Golf courses have the opportunity to teach sustainable landscape design principles to players if responsible landscaping practices are appropriately modeled.
Native plant species also provide wildlife with habitat and food sources, such as native flower areas that benefit pollinators. After establishment, site-appropriate plants normally require little to no irrigation.
Consider design intentions, ultimate sizes and growth rates of trees, shrubs, and ground covers when selecting and placing landscape plant. This reduces the need for future pruning and debris removal. In addition, the adaptability of plants to a specific site is important. Site-specific characteristics to consider include sun exposure, light intensity, wind conditions, drainage, and temperatures.
For recommended plant species in Delaware, see:
- Plants for a Livable Delaware. UD Extension.
- Livable Plants for the Home Landscape. UD Extension.
- Native Plants for Delaware Landscapes. University of Delaware Botanic Garden.
- Trees for Delaware. UD Extension.
- Tree Selection Guide. UD Extension.
- Livable Ecosystems: A Model for Suburbia. UD Extension.
- Certified Wildlife Habitats program. Delaware Nature Society.
- Plant Selection for Water Conservation. UD Extension.
- Delaware Native Plants for Communities in Kent and Sussex Counties. Delaware Nature Society.
- Native Plant Finder. Mt. Cuba Center.
- Native Plants for Wildlife Habitat and Conservation Landscaping/Chesapeake Bay Watershed. U.S. Fish & Wildlife Service.
- Avoid the introduction of invasive or potentially invasive plants. Control invasive or noxious weed species present on the site. The Delaware Invasive Species Council provides lists of invasive species. The state’s noxious weed list is managed DDA.
During landscape bed construction, use native soil and break up any remaining hardpan or compaction from construction. Slope beds away from buildings, with a minimum percent slope of 2 percent for at least 10 feet. Resolve drainage issues and establish clear drainage patterns prior to installing plants. Install plants with higher moisture requirements at lower elevations and drought-tolerant plants at higher elevations.
In general, the best times to plant trees and shrubs in Delaware are in early spring (March through early May) or in the fall (mid-August through October). These times reduce the stress on the plants by capitalizing on periods of cooler (but not cold) temperatures and increased moisture. However, many evergreens perform best if planted only in spring unless highly managed during establishment. Install herbaceous plants in late spring or earlier in fall to give these smaller plants a better chance to establish good root systems. Additional guidelines for planting in Delaware can be found in Landscape Management and Trees for Delaware.
Regardless of their ability to tolerate drought, all plants require supplemental irrigation during establishment. To increase water-use efficiency and improve plant establishment in landscaping, consider hand-watering individual plants for the first several months of the growing season. When it’s needed, water plants in the early morning to conserve water and avoid water loss due to evaporation. Water new trees and shrubs at least once a week to a depth of one foot and more frequently during dry weather. When using a hose, allow the water to trickle out for at least an hour, and move the hose several times around the base of the tree. Watering bags are effective tools for applying water slowly. Apply at least five gallons when watering from a container, pouring it slowly over the back of a shovel to spread the water. Keep trees well-watered throughout the entire establishment period (one year or more depending on the caliper) with deep, slow watering.
If trees and shrubs are planted in an area with an existing irrigation system, assess the coverage to determine whether changes should be made to identify areas where efficiency can be improved. Carefully assess landscape watering patterns to minimize spray on impervious surfaces, blockage of spray by plants or other obstructions, and runoff on slopes, clay soils, or compacted sites. Focus on the irrigation of woody plants at or beyond the dripline to promote extensive rooting. Periodically throughout the growing season, check the performance of the landscape irrigation system.
13.6 Use of Mulch
Mulch conserves soil moisture, mitigates temperature extremes, and reduces weed competition. During the growing season, mulch also serves as a visual reminder to keep mowers and string trimmers away from shrub stems and tree trunks. In winter, mulch helps prevent soil cracks from forming and exposing roots to cold temperatures and winter desiccation. Organic mulches include herbicide-free grass clippings (though avoid applying too deeply to avoid matting and heating the soil), shredded bark, bark chunks, composted sewage sludge, one-year-old wood chips, pine needles and composted, shredded leaves. Organic mulches are preferred, as non-organic mulches such as stone may add heat stress around annuals and perennials.
Annuals and perennials grow best with no more than 2 inches of mulch. Around trees and shrubs, mulch should be no more than 3 inches deep. With any planting, place mulch between the plants and not on top of the crown or against tree trunks or shrub canes. In the winter after the ground freezes, a deeper layer of coarse mulch (evergreen branches) over bulbs and other perennials can delay or prevent early growth and can be used to protect tender plants. Do not place a new layer of mulch over the old layer each year. Each spring, rake the old mulch to break up any hard crest and add only enough new mulch to maintain a 2-inch to 3-inch layer.
Correctly pruning trees, shrubs, and herbaceous perennials has multiple benefits throughout a landscape or golf course. Trees and shrubs are pruned first for safety. Pruning in some cases can increase plant health and result in better growth in future seasons. Typically, the ideal time to prune deciduous shade trees in Delaware is February to March, except in times of drought. Shrubs should be pruned based on their season of bloom (if the flowers are significant). Plants that bloom on second-year or old wood set their flower buds immediately after flowering and can be pruned for the month following bloom. Plants that bloom on new wood, or current-season wood, can be pruned in early spring prior to dormancy break. For more information on pruning, see:
- Trees for Delaware. Delaware Cooperative Extension.
- Pruning Evergreens. Delaware Cooperative Extension
- Pruning Woody Plants. Delaware Cooperative Extension
13.8 Pest Management
The same principles and methods identified in the IPM chapter of this document can be applied to landscaped areas. The following publications provide guidance specifically for these areas:
- What is Integrated Pest Management (IPM)? Delaware Cooperative Extension.
- Beneficial Insects (The Good Guys). Delaware Cooperative Extension.
- Garden Pests and Diseases. Delaware Cooperative Extension.
- Ornamentals Hotline newsletter. Delaware Cooperative Extension.
The Plant Diagnostic Clinic at the University of Delaware accepts plant samples showing signs or symptoms of disease. Visit the Plant Diagnostic Clinic website for more information on submitting samples. In addition, the University of Delaware’s Hot Topics in Plant Health blog provides links to timely plant-related information.
13.9 Landscape Best Management Practices
Planning and Design Best Management Practices
- Leave the majority of non-play areas — the perimeter zone — in natural vegetation.
- Enhance natural areas with supplemental plantings of native and adapted species.
- In landscaped areas, use natural drainage patterns and directional site grading to channel runoff away from impervious surfaces onto planted areas such as grass swales, filter strips, or rain gardens.
- Install rain gardens in locations where they can catch and temporarily hold runoff.
- Minimize the amount of area covered by paved surfaces. Where feasible, use permeable materials such as bricks laid on sand, interlocking pavers or pervious pavers, porous concrete, mulch, or plants.
Site Inventory and Assessment Best Management Practices
- Conduct an inventory of existing plants, their condition and quality, and their contribution to the overall style of the course.
- Conduct a soil analysis before choosing specific plants for landscape areas.
- Conduct a soil test before applying fertilizers. Modify pH if needed, based on soil test results.
- Amend the soil to improve soil texture and increase water infiltration.
Plant Selection Best Management Practices
- Select native species whenever possible; use adapted species or cultivars of native plants where appropriate.
- Select trees, plants, and grass species to attract birds and pollinators seeking wild fruits, herbs, seeds, nesting materials, cover, and insects.
- Know the ultimate sizes and growth rates of trees, shrubs, herbaceous plants, and ground covers.
- Select plants recommended for your specific location in Delaware.
- Choose the most stress-tolerant species for a particular area.
- Do not introduce invasive species into the landscape.
- Control or remove existing invasive species and noxious weeds.
Landscape Irrigation Best Management Practices
- Irrigate frequently during establishment.
- Water established plants based on their needs and, when needed, deeply and infrequently.
- Irrigate in the early morning to conserve water.
- Avoid water runoff onto impervious surfaces or slopes.
- Evaluate landscape irrigation performance periodically.
Mulching Best Management Practices
- Use mulch in landscaped beds.
- Use organic mulches whenever possible.
- Use only herbicide-free grass clippings when using grass clippings as mulch.
- Protect bulbs and other perennials in winter with a layer of coarse mulch (evergreen branches) to delay or prevent early growth.
Pruning Best Management Practices
- Hire a certified arborist to prune trees as the correct pruning cuts are essential to good tree health.
- Maintain pruning equipment to ensure clean cuts and less risk of damage to the plant.
- Prune deciduous shade trees in late winter (February to March), except in times of extreme drought.
- Prune shrubs based on their season of bloom.
Pest Management Best Management Practices
- Use IPM for landscaped areas.