2.10 Plant Materials

Ronald Reagan Courthouse,
Santa Ana, CA

Plant selection, including turf, shall be based on the plant’s adaptability to the region. Regionally mature plants are recommended in desert or areas of the country where water is scarce. The use of hearty native turf species or other ground cover is encouraged.

Existing Vegetation. GSA has a commitment to using sustainable design principles in the landscape. Therefore, all existing vegetation should be evaluated for appropriateness to remain. Where appropriate, existing trees and shrubs should be protected and a planting plan be built around them.

Species Selection
Plant selection should be based on the plant’s adaptability to the landscape area, desired effect, color, texture and ultimate plant size. Maximum water conservation can be achieved by selecting appropriate plants that require minimal amounts of supplemental water.

Hardiness and Availability. Plants must be hardy in the climate where they are to be planted.

Demanding Plants. Plants requiring meticulous soil preparation, fertilization and spraying shall be avoided.

Growth Habits. Plants need to be chosen with their mature size and growth habit in mind to avoid over planting and conflict with other plants, structures or underground utility lines.

Placement
Landscape design should be closely coordinated with the architectural characteristics of the building and the community where the building is located.

Trees should not be planted where potential intruders could use them to climb a wall or reach an upper story window. Care should be taken that the selected plant material in parking lot islands or adjacent to walkways will not grow over time to become hiding places for assailants, or create a traffic hazard by restricting sight lines. Turf should not be used for small islands in parking lots because it is too difficult to maintain. Trees, shrubs in low hedge rows and low-maintenance ground covers are more suitable in these locations.

Shade. Trees should be placed to provide shady sitting areas, reduce heat and glare on hard surfaces, and enhance pedestrian comfort.

Planting Practices
Tagging. For most projects, tagging of plant materials at the nursery should be employed only selectively for specimen plants. Instead, specifications should be tight enough to provide criteria for a rigorous inspection at the project site and rejection of plants if necessary.

Staking. Local conventions for staking, wrapping and guying trees should be followed. Local extension horticulturists can provide good advice.

Warranties. Warranties for the replacement of plant materials must be specified to extend for 1 year after the date of building acceptance by GSA or 1 year after installation of landscaping, whichever is later.

Mulch. Mulch selection should be made upon the basis of local practice. Bark products, pine needles or other organic materials are preferred over inert mulches, such as gravel which reflects heat and can burn plants, in all geographic areas except those where drought tolerant planting (cacti, etc) is proposed.Where hydroseeding is proposed, hydraulic mulch with recycled paper binders should be specified.