4.7.3 GENERAL LANDSCAPING STANDARDS | Aurora Unified Development Ordinance

4.7.3. GENERAL LANDSCAPING STANDARDS.

A. Landscape Reference Manual. Prior to the preparation of a formal landscape plan submittal, designers shall consult the Landscape Reference Manual, which is available on the City’s website, for specific requirements regarding plan setup, scale, notes, plant symbology, standard tables, and the Water-wise plant list.

1. General. Landscaping for all development shall include a variety of Water-wise plant materials, such as trees, shrubs, ornamental grasses, groundcovers, annual and perennial flowering species, turf grasses, and mulches that will provide visual interest during all seasons.

a. The use of plant materials adapted to the climatic conditions of the area shall be used to the maximum extent practicable in order to reduce water consumption, general maintenance, and the dependence on fertilizers and insecticides.

b. Landscape materials such as stone, masonry, wood, and steel may also be used to define space and create visual interest. When landscaped areas are adjacent to natural areas or open spaces, plants shall be selected to continue that native appearance along the border with the open space or natural area.

c. At least 75 percent of all annuals and trees, and 100 percent of shrubs, perennials, groundcovers, and ornamental grasses used to landscape each site regulated by this Section shall be selected from the Water-wise Plant List in the Landscape Reference Manual; the Colorado State University Cooperative Extension Facts Sheet on Xeriscaping; or other approved Water-wise, resource wise, or Xeriscape plant material references.

d. Trees and shrubs specified from another source other than the Water-wise plant list will be considered if the source for the Water-wise designation is listed on the plan. Such sources may consist of the Colorado State University Extension office or similar sources. Applicants may also consult with the City Forester regarding any proposed tree species not on the approved Water-wise plant list.

e. Evergreen trees such as Austrian and Ponderosa Pine as well as Spruce, shall not be planted closer than 20 feet to a street edge, sidewalk, or parking area as measured from the trunk of the tree to the edge of the pavement.

f. Planting within rip-rap lined swales is prohibited. No trees, shrubs, and/or perennials shall be planted within the rock.

2. Minimum Plant Sizes. Plant material shall be installed in the minimum sizes shown in Table 4.7-1. Trees shall be measured six inches above ground level for all trees up to four inches in caliper and 12 inches above ground level for larger trees.

Table 4.7-1 Minimum Plant Sizes
Type of Planting	General Minimum Size Requirement	Special Locations [1]
Shade trees	Two inch caliper minimum standard. Two and one-half inch caliper minimum for street trees along arterial and collector streets.	Three-inch caliper
Ornamental trees	Two-inch caliper minimum (for single stem varieties). Clump forms, multi-stemmed, and similar are acceptable and shall be six to eight feet in height at time of installation.	Two and one-half inch caliper
Evergreen trees	Six feet tall	8 -10 feet high
Shrubs	Five-gallon container
Ornamental grasses and perennials	One-gallon container
Notes: [1] Special Locations include non-residential or mixed-use development along property lines adjacent to residential uses.

3. Tree and Shrub Diversity. Tree and shrub diversity shall comply with the Landscape Reference Manual to the maximum extent practicable.

a. The following plants shall be prohibited from being planted in the City:

i. Russian Olive (all Elaeagnus Angustifolia species and cultivars);

ii. Aspen (all Populus Tremuloides species and cultivars);

iii. Cottonwood (all species), unless being used to continue the native appearance along the border with open space or natural areas or within non-street frontage buffers, but not in connection with curbside landscape areas or abutting walks and/or buildings;

iv. Tamarisk (all species);

v. Ash (Fraxinus species);

vi. Siberian Elm (Ulmus pumia); and

vii. Tree of Heaven (Ailanthus sp.).

b. Plants listed as an invasive species by the Colorado State University Extension Service are prohibited.

c. Plants listed on the Colorado Noxious Weed List are prohibited.

a. General Requirements. This Section 146-4.7.3.B.5 applies to all required landscapes unless exempted by Subsection b below or by another provision of this UDO.

i. Areas within and immediately adjacent to public rights-of-way having no reasonable means of providing an underground automatic irrigation system shall with the approval of the Planning Director be landscaped with a minimum of two materials as listed below. One of the two materials must be plant material. Forty percent of the total landscape area must be permeable materials. Twenty percent of the permeable material area must be plant material. A homeowner’s yard visible from the public right-of-way shall not consist of entirely non-living materials.

(a) Plant material – to be hand watered if no automatic irrigation system is available

(b) Rock, no white rock

(d) Integrally colored stamped decorative concrete

(e) Shredded cedar or wood chip mulch

6. Plant Quality and Installation. All plant materials shall meet or exceed minimum standards as outlined by the Colorado Nursery Act Regulations and the current edition of the Uniform Nursery Standards, and shall be installed according to specifications of the Associated Landscape Contractors of Colorado.

a. Tree Equivalents. The following tree equivalents are provided to allow design flexibility in applicable situations as provided in this UDO. One tree equivalent shall be equal to:

i. One 2.5 inch caliper deciduous shade tree;

ii. One 2 inch caliper deciduous shade tree;

iii. One 2 inch caliper ornamental tree;

iv. One 6 foot tall evergreen tree;

v. Twelve 5 gallon shrubs per one 2.5 inch caliper tree or 8 foot to 10 foot tall evergreen tree; or

vi. Ten 5 gallon shrubs per one 2 inch caliper tree or 6 foot tall evergreen tree.

b. Shrub Equivalents. The following shrub equivalents are provided to allow design flexibility in applicable situations as provided in this UDO. Shrub equivalents apply to either deciduous or evergreen species. One five gallon shrub equivalent shall be equal to:

i. Three 1 gallon perennials; or

ii. Three 1 gallon ornamental grasses

a. Plant beds shall be separated from turf and other areas by metal edging or approved equivalent material.

b. All shrubs, ornamental grasses, perennials, and groundcovers shall be located within plant beds.

c. The installation of individual shrub species in turf or native seed areas without metal edging, but with hand-dug spade edges, may be approved by the City based on likelihood of survival and potential impacts on surrounding vegetation.

d. Where rock is the chosen mulch treatment and no plant material will be installed, weed barrier fabric shall be used to block weed growth and conserve moisture. Crusher fines may not be used as a mulch treatment unless specified as permitted in another section of the UDO.

e. Trees and shrubs shall be mulched by either rock or wood mulch, or a combination of both, at the discretion of the designer. Shredded cedar is the preferred mulch treatment around all plant material as it has moisture retention qualities unlike rock mulch that retains and radiates heat around plants.

f. For wood mulch applications, all trees shall be surrounded by an area of mulch that shall be no less than three inches in depth and no less than three inches from the trunk to reduce potential damage from insects. Mulch shall be a minimum of three inches from trunks to reduce insect and trunk damage.

g. All plant beds shall be mulched to a minimum depth of three inches. Areas planted with perennials and groundcovers species shall be mulched to a minimum two inches in depth.

9. Thorny Plants and Shrubs. Shrubs that have thorns shall not be planted within 8’ of public walks or within parking lot islands. Trees that drop fruits or have thorns shall not be planted within 20 feet of public walks or within parking lot islands or medians.

10. Clear Space Above Walks. Trees planted adjacent to public sidewalks shall maintain an eight foot or greater tree branching height above the walks when mature.

11. Artificial Turf Standards. Where this UDO permits the use of artificial turf, it shall comply with the following standards.

i. Artificial turf may be used in sports field applications.

ii. Artificial turf may be used in front yards to replace sod or native seed areas of single-family residential lots if approved by a homeowners’ association and/or Title 32 District. Homeowners shall meet the Residential Yard Landscape Requirements per Table 4.7-3 in addition to providing artificial turf.

iii. Artificial turf may be used in commercial developments.

iv. Artificial turf may be used in street frontage buffers.

v. Artificial turf may be used in dog parks.

vi. Artificial turf may be used in back yards.

b. Materials. Artificial turf shall be of a type known as cut pile infill and shall be manufactured from polypropylene, polyethylene, or a blend of polypropylene and polyethylene fibers stitched onto a polypropylene or polyurethane mesh or hole-punched backing. Hole-punched backings shall have holes spaced in a uniform grid pattern with spacing not to exceed four inches by six inches on center.

c. Installation. Artificial turf shall be installed per the manufacturer’s recommendations.

d. Slope Restrictions. The installation of artificial turf on slopes greater than 6.6 percent shall require the applicant to consult with the manufacturer on recommendations for installation and use.

e. General Appearance. Artificial turf shall be installed and maintained to effectively simulate the appearance of a well-maintained turf grass.

i. Artificial turf may not be used within curbside planting areas in any zone district.

Editor’s note: The provisions of this subsection were repealed by Ord. 2023-41, enacted September 11, 2023.

iv. Artificial turf may not be used to satisfy any requirements of this Section 146-4.7 (Landscape, Water Conservation, Storm water Management) unless this Section 146-4.7 or another section of this UDO contains a specific provision allowing such use.

v. Where this UDO permits the use of artificial turf or natural turf, the use of indoor or outdoor plastic or nylon carpeting or other materials or combinations of materials as a replacement for artificial turf or natural turf is prohibited.

12. Turf Regulations. The design of all new turf areas shall comply with the following requirements:

i. Turf Area Limitations for Each Lot Containing Single-Family Detached, Two-Family and Single-Family Attached Duplex Homes. Turf requirements for such areas shall be subject to all the requirements listed in Table 4.7-3, Residential Yard Landscape Requirements and Section 138-191 of the Aurora City Code.

ii. Turf Area Limitations for All Other Development Areas Except Playfields. In all other development sites except playfields, areas as defined by Section 138-191 of the Aurora City Code, Use of Turf and Ornamental Water Features, the use of cool-season grass sod, seed and seed mixtures that contain cool-season grass species shall be limited to not more than 33 percent of the site’s total landscaped areas. The area consisting of high-water using species of cool-season grasses such as Kentucky bluegrass shall be contiguous. For the purposes of these standards “contiguous” shall mean all abutting areas and areas that may be separated by a pedestrian walk or trail. Areas separated by pavement used for vehicular circulation are not considered contiguous.

i. High-Water Usage Cool-Season Grasses. A cool-season grass species shall be considered high-water use if it requires more than 15 inches of annual irrigation.

1. New landscaped areas, plant beds, raised planters, and plant containers, with the exception of non-irrigated native, dryland, and restorative grasses shall be watered by a permanent automatic irrigation system meeting all adopted Aurora Water engineering standards, which may be found on the City’s website.

2. Automatic rain shutoff sensors shall be installed in all irrigation systems.

3. The Aurora Water Department requires all non-single-family landscapes to be divided into water conserving (non-turf), nonwater conserving (turf), and non-irrigated areas (e.g., pavement). A separate hydrozone plan is required for submittal with the landscape plan. Refer to the Landscape Reference Manual for plan requirements. (Ord. No. 2023-41 § 4, 09-11-2023; Ord. No. 2023-29 § 1, 07-31-2023; Ord. No. 2020-37 § 18, 10-05-2020; Ord. No. 2019-49 § 1, 08-19-2019)