§ 22-523. Landscaping.

   1.   General. Landscaping plants intercept rainfall, reduce storm water runoff, prevent erosion, and reduce the need for detention. Landscape plants also provide shade and reduce the temperature created by additional impervious surfaces. Plants release moisture back into the environment, improve air quality, and remove contamination from the soil and water by absorbing excess nutrients, filter sediments, and break down pollutants. Planting native plants helps provide habitat, food, and protection for native species and ecosystems. Planting native species generally increases the chance for long term survivability of the plant because they are naturally adapted to local conditions. Planting non-native species and cultivars could be incorporated in designs when they provide a superior plant for spatial constraints and urban stress mitigation found in local site conditions. Existing significant trees which help contribute to the sense of place should be preserved to the maximum extent practical.

   2.   Design Guidelines.

      A.   Native plant materials should be incorporated in all designs. The use of native plant material can help improve water quality, provide additional and improved wildlife habitat, and typically adapt to local conditions which then require less maintenance. Native plants must be used near greenways, suburban forested areas, wetlands, and riparian areas.

      B.   Except as noted above, non-native plants may be included in place of a native plant if it is not considered invasive and the plant does not introduce pests or diseases. A non-native plant may be incorporated into designs when they prove to be better suited for the soil, environment, or spatial constraints, urban stress mitigation, and integration into the surrounding ecosystem.

      C.   The following is a list of invasive plants which may not be used in any urban planting schedule:

         (1)   Trees. Tree-of-heaven (ailanthus altissima), norway maple (*acer platanoides), sycamore maple (acer pseudoplatanus), empress tree (paulownia tomentosa), callery pear (*pyrus calleryana), siberian elm (ulmus pumila)

         (2)   Shrubs. Japanese barberry (*berberis thunbergii), European barberry (berberis vulgaris, russian olive (elaegnus angustifolia), autumn olive (elaeagnus umbellate), winged euonymus (*euonymus alatus), border privet (ligustrum obtusifolium), common privet (ligustrum vulgare), tartarian honeysuckle (lonicera tartarica), standish honeysuckle (lonicera standishii), morrow’s honeysuckle (lonicera morrowii), Amur honeysuckle (lonicera maackii), bell’s honeysuckle (lonicera morrowii x tatarica), common buckthorn (rhamnus catharticus), glossy buckthorn (rhamnus frangula), wineberry (rubus phoenicolasius), multiflora rose (rosa multiflora), Japanese spiraea (*spiraea japonica), guelder rose (*viburnum opulus var. opulus).

         (3)   Grasses. Cheatgrass (bromus tectorum), Japanese stilt grass common reed (phragmites australis), reed canary grass (phalaris arundinacea), johnson grass (sorghum halepense), and bamboo (poaceae), shattercane (sorghum bicolor ssp. drummondii)

         (4)   Flowers. Garlic mustard (alliaria petiolata), goutweed aegopodium podagraria), bull thistle (crisium vulgare), canada thistle (cirsium arvense), musk thistle (carduus nutans), jimsonweed (datura stramonium), goatsrue (galega officinalis), giant hogweed (heracleum mantegazzianum, dame’s rocket (hesperis matronalis), purple loosestrife (lythrum salicaria, L. virgatum), eurasian water-milfoil (myriophyllum spicatum), star-of-bethlehem (ornithogallum nutans, umbellatum), japanese knotweed (polygonum (falopia) cuspidatum/ polgonum sachalinense), wild parsnip (pastinaca sativa), beefsteak plant (perilla frutescens), lesser celandine (ranunculus ficaria), water chestnut (trapa natans).

         (5)   Vines. Fiveleaf akebia (akebia quinata), porcelain-berry (ampelopsis brevipedunculata), oriental bittersweet (celastrus orbiculatus), japanese honeysuckle (lonicera japonica), kudzu (pueraria lobata), mile-a-minute vine (polygonum perfoliatum).

* Species with cultivars that are known to be non-invasive may be acceptable within a planting plan.

   3.   Street Trees / Screening / Vegetative Buffering.

      A.   Any existing vegetation that is in appropriate locations, of an acceptable species and quality may be used to fulfill landscaping or buffering requirements.

      B.   Any landscaping should create, or be part of the process to create larger landscape patches and corridor ecosystems and larger interior areas and less edge areas. Connectivity to existing landscaping shall be encouraged.

      C.   In order to aid surveillance and minimize the potential for crime, planting shall also be sited, massed, and scaled to maintain visibility of doors and first floor windows from the street and from within the development to the greatest extent possible. Planting patterns shall not obstruct sight lines or create isolated areas, especially near pedestrian walking paths.

      D.   Trash disposal areas, such as dumpster or compactor sites, shall be effectively screened so as to be screened with a combination of architectural masonry (or fencing) and/or landscaping with a height of at least 6 feet.

      E.   Open areas should also include but not be limited to at least 4 of the following:

         (1)   Seasonal planting areas;

         (2)   Large deciduous trees;

         (3)   Seating;

         (4)   Pedestrian scale lighting;

         (5)   Gazebos or other decorative shelters;

         (6)   Play structures for children;

         (7)   Natural environment areas;

         (8)   Recreational amenities; or

         (9)   Trails.

      F.   All planting shall be performed in conformance with good nursery and landscape practice. Plant materials shall conform to the standards recommended by the American Association of Nurserymen, Inc., in the American Standard of Nursery Stock, ANZIZ60, current edition, as amended.

         (1)   Provide a landscape plan note indicating that the top of the main order root (first large set of roots that divide from the trunk) shall be planted no lower than 1 or 2 inches into the soil.

         (2)   Planting designs are encouraged to share planting space for optimal root growth whenever possible. Continuous planting areas vs. isolated planting boxes are encouraged.

         (3)   No staking and wiring of trees shall be allowed without a maintenance note for the staking and wiring to be removed within 1 year of planting.

         (4)   All street trees shall be provided by the applicant in accordance with the following standards:

            (a)   The trees shall be nursery grown in a climate similar to that of the locality of the project. Varieties of trees within the right-of-way shall be subject to the approval of the authority that accepts ownership of the street.

            (b)   All trees shall have a normal habit of growth and shall be sound, healthy, and vigorous; they shall be free from disease, insects, insect eggs, and larvae.

            (c)   The trunk caliper, measured at a height of 6 inches above finish grade shall be a minimum of 3 inches.

            (d)   Tree planting depth shall bear the same relationship to the finished grade as the top of the root ball or original grade of origin.

            (e)   All required landscape plants shall be maintained and guaranteed for a length of 24 months from the date of planting. No more than 1/3 of the tree or shrub shall be damaged or dead without replacement. Replacement plants shall conform to all requirements of this section and shall be maintained after replanting for an additional 24 months.

            (f)   The plant’s growth shall not interfere with the street cartway, sidewalk, signage, easements, clear sight triangles, or utility line. Within the clear sight triangle, typical branching shall not be within 10 feet of ground level after 10 years of growth.

            (g)   No one species shall comprise more than 33% of the entire number of street trees in a particular development.

            (h)   Existing significant trees and natural features, such as drainage corridors, shall be preserved to the maximum extent practicable and incorporated into site plans and site design as major amenities.

            (i)   If a significant tree is designated to be preserved but is removed or substantially damaged during the clearing, grading, or construction, the applicant or developer shall be required to replace the removed or damaged tree with one approved by the Shade Tree Commission.

      G.   Street trees shall be provided in all land developments which include new streets.

         (1)   Street trees shall not be located farther than 40 feet away from the new street right-of-way.

         (2)   The number of street trees shall be based on 2 street trees required for every 100 linear foot of new street measured from the centerline.

         (3)   The spacing of trees shall be based on the size of the tree canopy at maturity with trees spaced no closer than 30 feet on center if the tree canopy is less than 30 foot spread at maturity, spaced 30-60 feet on center if the tree canopy is 30 to 50 feet spread at maturity, and street trees spaced 50 to 100 feet on center if the tree canopy is over 50 feet spread at maturity. When a less formal arrangement is desired, where more massing is appropriate, or improvements such as benches are located grouping of street trees is encouraged.

         (4)   Street trees shall be one of the following species:

Common Name	Botanical Name	Height/ Spread	Drought Tolerances	Soil Type	Soil Acidity/ Aerosol Salt Tolerance	Soil Saturation Preference	Root Pattern	Canopy Structure/ Growth Rate
Red Maple	Acer rubrum	75/35	Moderate	Clay; loam;	Acidic/ Low tolerance	Extended flooding to well drained	Large surface roots	Upright oval canopy/ fast growing
Sugar Maple	Acer saccharum	70/40	Sensitive to reflected heat and drought	Sand; loam. Not compacted	Acidic; alkaline/Not tolerant	Well drained	Often shallow	Dense Oval/ Mod-slow growing
River birch	Betula nigra	40-50/ 25-35	Moderate	Clay; loam	Acidic	Extended flooding to well drained	Not a problem	Narrow- pyramidal crown/ Fast growing when moist
Common Hackberry	Celtis occidentalis	45-80/ 40-50	Highly tolerant	Clay; loam	Tolerant of highly alkaline to moderate acidic	Extended flooding to well drained	Large surface roots	Round/ Prune to prevent weak branch crotches
American Yellowwood	Cladrastis kentuckea	30-50/ 40-50	Moderate	Clay; sand; loam	Alkaline; acidic	Occasional wet to well-drained	Surface roots when wet	Round/ Moderate/ Prune structure
American beech	Fagus grandifolia	50-75/ 40-60	Moderate to low	Sand; loam	Acidic/ Low Tolerance	Needs well-drained	Surface roots/ Needs space	Very dense oval/ Moderate
White ash	Fraxinus americana	50-80/ 40-60	Moderate	Sand; loam	Alkaline; acidic/Highly tolerant	Extended flooding to well- drained	Large surface roots/ Needs space	Oval/Fast growing
Green Ash	Fraxinus pennsylvan- ica	60-70/ 45-50	Highly tolerant	Sand; loam; clay	Alkaline; acidic/ Moderately tolerant	Extended flooding to well- drained	Large surface roots develop when confined	Upright/ Fast; Prune structure to develop trunk
Thornless Honey-locust	Gleditsia triacanthosinermis	50-70/ 35-50	Highly tolerant	Clay; sand; loam	Alkaline; acidic/Highly tolerant	Occasional wet to well- drained	Can grow surface roots	Open oblong
Sweetgum	Liquidambar styraciflua	60-75/ 35-50	Moderate to little	Clay; sand; loam	Acidic/ Moderately tolerant	Extended flooding to well- drained	Surface roots when moist	Pyramidal/ Extreme sensitivity to construction
Tuliptree	Liriodendron tulipifera	80-100/ 30-50	Moderate	Sand; loam	Acidic/ No tolerance	Well- drained to occasional wet	Not a problem Needs space	Oval/ Moderate growth
Blackgum/ Sourgum	Nyssa sylvatica	65-75/ 25-35	Highly tolerant	Clay; loam	Acidic/ Moderately tolerant	Extended flooding to well- drained	Not a problem; deep roots	Pyramidal/ Slow growth
American Hophorn- beam	Ostrya virginiana	25-50	Tolerant once establish	Sand; loam	Poor salt tolerance pH adaptable	Prefers moist when young	Not a problem	Rounded
Sycamore	Platanus occidentalis	75-90/ 50-70	Highly tolerant	Clay; loam; should not dry out	Alkaline; acidic/ Moderately tolerant	Extended flooding to well- drained	Can grow surface roots	Dense pyramidal/ Fast growing
White Oak	Quercus alba	60-100/ 60-80	Moderate to low	Sand; loam; should not dry out	Acidic/ Highly tolerant	Occasional wet to well- drained	Not a problem	Pyramidal/ Slow growing
Shingle Oak	Quercus imbricaria	40-60/ 40-60	Tolerant intermittent drought	Rich; deep; well drained	Alkaline soils up to 7.5 pH	Moist	Not a problem	Rounded/ Transplants well
Chestnut Oak	Quercus montana	50-60/ 40-60	Highly tolerant	Sand; loam	Acidic/ unknown salt tolerance	Well- drained	Root flare when older	Round/ Moderate growth
Red Oak	Quercus rubra	60-70/ 50-60	Highly tolerant	Sand; loam	Acidic/ Highly tolerant	Well-drained	Can for large surface roots	Dense; round/Fast growth; Train into one leader
Swamp White Oak	Quercus bicolor	50-70/ 50-70	Moderate	Clay; sand; loam	Acidic/ Moderate tolerance	Extended flooding to well- drained	Not a problem	Round/ Moderate growth; long lived
Basswood/ American Linden	Tilia americana	50-80/ 35-50	Moderate	Sand; loam	Acidic; alkaline/ Low tolerance	Well- drained	Not a problem; Needs space	Dense; Pyramidal/ Moderate
Other tree species may be used provided acceptable information is submitted to indicate that the species are hardy trees or fits the sites ecosystem.

 

   4.   Ground Cover. Ground cover shall be provided on all areas of the project to prevent soil erosion. All areas which are not covered by paving, stone, or other solid material shall be protected with a suitable ground cover, consisting of spreading plants including sods and grasses less than 18 inches in height.

   5.   Existing Wooded Areas. No more than 20% of existing woodlands located in environmentally sensitive areas shall be destroyed or altered. If the applicant can prove that invasive species are within either of these areas, then the percent of woodlands to be removed may be increased to eradicate invasive species.

   6.   Tree Protection Zone.

      A.   Prior to construction the tree protection zone shall be delineated at the dripline of the tree canopy. All trees scheduled to remain shall be marked; however, where groups of trees exist, only the trees on the edge need to be marked. A 48-inch high snow fence or 48-inch high construction fence mounted on steel posts located 8 feet on center shall be placed along the boundary of the tree protection zone.

      B.   No construction, storage of material, temporary parking, pollution of soil, or regrading shall occur within the tree protection zone. When there is a group of trees, the tree protection zone shall be based on the location of the outer trees.

(Ord. 614, 5/11/2015)