New Orleans Comprehensive Zoning Ordinance

Printed: 7/21/2024 7:30:29 AM

23.5 General Landscape Design Standards

Landscape plans, as described above, shall be prepared by a registered landscape architect licensed by the Louisiana Horticulture Commission.  However, a horticulturalist/landscape contractor licensed in Louisiana may be used for projects that do not require a stormwater management plan and where the horticulturalist/landscape contractor is performing the installation. A landscape plan shall be evaluated and approved based on the following design criteria.

23.5.A Scale and Nature of Landscape Material   

The scale and nature of landscape materials shall be appropriate to the size of the site and related structures. 

23.5.B Selection of Plant Material   

Plant material shall be selected for its form, texture, color, pattern of growth, and suitability to local conditions. All landscape plans shall incorporate at least fifty percent (50%) of native trees and shrubs into required plant materials to provide habitat for wildlife, reduce irrigation requirements and promote the sustainability and survivability of plant material.

23.5.C Trees   

1. When adjacent to sidewalks, trees shall have a minimum height of twelve (12) feet at planting with a minimum canopy clearance of six and a half (6.5) feet in order to allow pedestrian passage.

2. All deciduous shade trees at the time of installation shall have a minimum caliper of two and one-half (2.5) inches for single trunk trees and one and one-quarter (1.25) inches for multi-trunk trees, and a clear trunk height of at least six (6) feet, unless otherwise specified. Caliper is measured at six (6) inches above the ground for trees up to four (4) inches in caliper.  If the caliper exceeds four (4) inches at six (6) inches above the ground, caliper is measured at twelve (12) inches above the ground as per ANSI Z60. 

3. Evergreen trees shall have a minimum height of eight (8) feet at planting.

4. Single stem ornamental trees shall have a minimum caliper of three (3) inches taken at six (6) inches above ground, unless otherwise specified. Multiple stem ornamental trees shall have a minimum height of eight (8) feet at planting and a minimum of three (3) trunks with a minimum one and a half (1.5) inch caliper each, with five (5) trucks maximum.

23.5.D Shrubs   

1.  Unless otherwise specified, all large deciduous and evergreen shrubs shall have minimum height of three (3) feet at installation, and all small deciduous and evergreen shrubs shall have a minimum height of eighteen (18) inches at installation.

2.  Large shrubs are those species that reach five (5) or more feet in height at maturity. Small shrubs are those species that can grow up to five (5) feet in height if left unmaintained, but are generally kept at heights of eighteen (18) to thirty-six (36) inches. 

23.5.E Perennials and Groundcover   

Unless otherwise specified, perennials and groundcover shall be a minimum of four (4) inch container stock.

23.5.F Mulch   

Unless otherwise specified, mulch shall be a minimum two (2) inch dressing and shall be applied on all exposed soil surfaces of planting areas, except turf, creeping or rooting groundcovers, or direct seeding applications, where mulch is contra-indicated. Mulch shall be kept from direct contact with tree trunks and organic material. All mulch shall derive from a living, natural source.

23.5.G Irrigation   

Sprinkler irrigation systems are required for landscaped areas when natural systems are not available or are not part of a stormwater BMP. The type of plant material, the condition, and growing medium where they are installed, and sun exposure shall dictate the type of sprinkler irrigation system(s). All irrigation systems shall be designed to minimize the use of water and shall be approved as part of the landscape plan. When irrigation is installed, it shall comply with the following standards:

1. Automatic controllers shall be set to water between 7:00 p.m. and 10:00 a.m. to reduce evaporation.

2. Irrigation systems shall be designed to avoid runoff, low-head drainage, overspray, or other similar conditions where water flows or drifts onto adjacent property, non-irrigated areas, walks, roadways, or structures.

3.  Irrigation equipment shall comply with the following standards.

a. Low-volume irrigation systems with automatic controllers are required. Low-volume irrigation systems include low-volume sprinkler heads, drip emitters, and bubbler emitters.

b.  Drip, trickle or other low-volume irrigation shall be provided on at least ninety percent (90%) of the landscape areas except for those areas devoted to turf and flat groundcover plants. If a licensed landscape architect or landscape contractor verifies that a drip or trickle system is not feasible due to location, the required percentage of drip or trickle irrigation may be reduced by  technical decision of staff approving the landscape plan.

c. Integral, under-the-head, or in-line anti-drain valves shall be installed as needed to prevent low-head drainage.

d.  Automatic control systems shall be able to accommodate all aspects of the design. Automatic controllers shall be digital, have multiple programs, multiple cycles, and sensor input capabilities.

e.  Soil moisture sensors and rain or moisture-sensing override devices are mandatory.

f.  Sprinkler heads shall be selected and spaced for proper area coverage, application rate, operating pressure, and adjustment capability. Sprinklers shall have matched precipitation and application rates within each control valve circuit.

g.  Drip irrigation systems are permitted if commercial or agricultural grade materials are used. Components shall be installed below the soil except for emitters.

h.  Backflow prevention devices are required.

i. Rainwater harvesting and/or dedicated landscape water meters are recommended on all landscape areas to facilitate water management and cost reduction.

23.5.H Water Waste Prevention   

Water waste resulting from inefficient landscape irrigation is prohibited. Water waste from irrigation is defined as runoff that leaves the target landscape due to low head drainage, overspray, or similar conditions where water flows onto adjacent properties, non-irrigated areas, walks, or roadways. Overspray and runoff are not considered water waste from irrigation if either one of the following conditions are met:

1. The landscape area is adjacent to semi-pervious or pervious surfaces.

2. The adjacent non-permeable surfaces are designed and constructed to drain entirely to landscape.

23.5.I Energy Conservation   

Plant material placement shall be designed to reduce the energy consumption needs of the development. Shade trees shall be included on the exposed west and south elevations when landscape is required.

23.5.J Species Diversity   

Diversity among required plant material for on-site landscape is required. This provides visual interest and reduces the risk of losing a large population of plants due to disease. Table 23-1: Diversity Requirements indicates the percentage of diversity required based on the total quantity of species being used. For example, if a development requires forty-five (45) shade trees, no more than eighteen (18) trees nor less than five (5) trees can be of one (1) species, and there shall be a minimum of five (5) different species within the forty-five (45) trees. 

Table 23-1: Diversity Requirements

TOTAL NUMBER OF PLANTS PER PLANT TYPE

DIVERSITY REQUIREMENTS

MINIMUM NUMBER OF SPECIES

MAXIMUM OF ANY SPECIES

MINIMUM OF ANY SPECIES

1-4

100%

Not Applicable

1

5-10

60%

40%

2

11-15

45%

20%

3

16-75

40%

10%

5

76-500

25%

5%

8

500-1,000

30%

5%

10

1,000+

15%

4%

15

23.5.K Planting   

In order to meet the landscaping requirements of this Ordinance, plant material shall be planted in the ground. Landscape planted within planters and raised planter boxes are not considered to meet the landscape requirements. 

23.5.L LYN Sustainable Landscaping Principles   

Landscape plans shall contain ample notes, specifications, and details to guide landscape horticulturist (contractors) and landscape maintenance companies, master gardeners, general gardeners, lawn service companies, irrigation installers and property owners to do their share in getting the landscape to maintain its self in a sustainable manner subject to the landscaping principals published by the LSU AgCenter, Louisiana Yards and Neighborhoods (LYN) Program, A Guide to Louisiana-Friendly Landscaping, latest addition.