2. Selection, Installation and Maintenance.
A. Selection.
(1) All plant materials must be of good quality and meet American Horticulture Industry Association (AmericanHort) or its ANSI accredited successor’s standards for minimum acceptable form, quality, and size for species selected.
(2) All species must be capable to withstand the seasonal temperature variations of USDA Hardiness Zone 5b (the plant zone for North Liberty). A hardiness zone is a geographically defined area in which a specific category of plant life is capable of growing, as defined by climatic conditions, including its ability to withstand the minimum temperatures of the zone.
(3) The use of species native or naturalized is required. Drought tolerant species are encouraged.
(4) Invasive species are prohibited.
B. Installation.
(1) All landscape materials must be installed in accordance with current nursery industry standards, and must be properly supported to ensure survival. Support devices such as guy wires or stakes must not interfere with pedestrian or vehicular movement.
(2) If landscape material is located within a utility easement and repair or replacement of the utility is needed, the City or utility is not responsible for the replacement of any landscape that may be damaged.
(3) All plant materials must be free of disease and installed so that soil of sufficient volume, composition, and nutrient balance are available to sustain healthy growth.
(4) Landscaping materials shall be planted as each phase of a site is developed.
(5) If weather prohibits the installation of landscape materials, a security bond for 125% in favor of the City of the estimated amount of landscape materials and installation cost. The cost of landscape materials and installation must be determined by a landscape architect or other landscape business professional.
C. Landscape materials depicted on approved landscape plans are considered a required site element. As such, the owner of record or the business or homeowner’s association is responsible for the maintenance, repair, and replacement of all landscape materials and elements.
3. Minimum Planting Sizes. Minimum planting sizes are as follows. For the purposes of determining trunk size, the diameter/caliper is measured at six inches above ground level, unless otherwise specified in current ANSI accredited Horticultural Standards.
A. Evergreen trees must have a minimum height of six feet.
B. Shade trees must have a minimum clear trunk height of four feet above the ground with a two-inch caliper.
C. Single stem ornamental trees must have a minimum trunk size of two inches in caliper. Multiple stem ornamental trees must have a minimum height of eight feet.
D. Evergreen or deciduous shrubs must have a minimum height of 18 inches.
4. Berming. If berms are included on a landscape plan, they must comply with the following:
A. Berms must be stabilized to prevent erosion.
B. Berms must be a minimum of two feet in height.
C. Berms of two feet in height and up to six feet in height are limited to a maximum slope of 3:1, as measured from the lot line.
D. Berms of six feet in height or more are limited to a maximum slope of 4:1, as measured from the lot line.
E. Berms must undulate by height and/or width for visual interest.
5. Parking Lot Landscape. A perimeter landscape area is required for all parking lots adjacent to streets and public spaces such as a plaza, public seating area, or park. The landscape treatment must run the full length of the parking lot perimeter and must be located between the lot line and the edge of the parking lot, with the exception of pedestrian walkways. The landscaped area must be improved as follows:
A Shrubs must be planted and spaced sufficiently to form a continuous linear hedgerow at plant maturity.
B A minimum of one shade tree must be provided for every 50 linear feet of perimeter landscape yard. Two ornamental trees may be substituted for one shade tree and must be spaced one ornamental tree every 25 feet. Trees may be spaced linearly on-center, or grouped to complement an overall design concept.
C Trees within parking lot islands adjacent to parking lot landscaping areas may be included in the calculation for minimum number of required trees.
6. Parking Lot Interior Landscape. All parking lots consisting of 15 or more spaces require interior parking lot landscape as described in this section.
A. All rows of parking stalls must terminate in a parking lot island or landscape area.
B. Where more than 15 parking stalls are provided in a row, one parking lot island must be provided between every 15 parking spaces. As part of the landscape plan approval, parking lot island locations may be varied based on specific site requirements or design scheme, but the total number of islands must be no less than the amount required of one island for every 15 spaces.
C. Parking lot islands must be at least the same dimension as the parking stall. Double rows of parking must provide parking lot islands that are the same dimension as the double row.
D. A minimum of one shade tree must be provided in every parking lot island or landscape area. If a parking lot island extends the width of a double row, then two shade trees are required.
7. On-Site Trees. In addition to trees in required buffer yards, on-site shade trees must be installed as follows:
A. Multi-Unit Residence District. One tree for each 750 square feet of building footprint.
B. Residential Manufactured Home Park District. One tree for every four acres.
C. Commercial, Industrial and Public Districts. One tree for every 2,000 square feet of building footprint.
D. Trees within parking lot landscape and parking lot islands adjacent to parking lot landscape may be included in the calculation for minimum number of required trees.
8. Buffer Yards.
A. Buffer yards are required for new construction along interior side and rear yards in the following cases:
(1) Where the lot line of a multi-unit residence development is adjacent to the lot line of a single-unit residence or two-family residence district.
(2) Where a non-residential use is located within a residential or interim development district.
(3) Where the lot line of a non-residential district is adjacent to the lot line of a residential district. This does not include private or public parks.
B. The required design for buffer yards is as follows:
(1) A buffer yard must be a minimum of 10 feet in width.
(2) One shade or evergreen tree must be planted for every 30 linear feet of buffer yard length. As part of the landscape plan approval, trees may be spaced at various intervals based on specific site requirements, but the total number of trees planted must be no less than one per 30 linear feet of buffer yard length.
(3) Existing trees in the buffer yard may count toward the buffer yard tree requirement. This credit is a 1:1 ratio (one existing tree for one proposed tree) regardless of the size of the existing tree.
(4) Evergreen shrubs must be planted and spaced sufficiently to form a continuous linear hedgerow at plant maturity. As part of the landscape plan approval, shrubs may be spaced at various intervals based on specific site requirements, but the total number of shrubs planted must be no less than one per three linear feet of buffer yard length.
(5) A fence may be required at the discretion of City staff.
9. Site Landscape. Areas of any lot that are not covered by structures or pavement must be planted with live landscaping. Stone, mulch, or other permeable landscape materials may be used to satisfy this requirement, but must not cover more than 40% of such area and must be designed so such materials are placed so that they are no higher than the height of the curb to prevent spill.