9.2.3 Plant Material Requirements
Unless specified elsewhere in this Ordinance, plant material shall meet the minimum requirements listed below. When determining the quantity of plant material required, the quantity shall always be rounded up to the nearest whole number.
A. Plant Materials, General
All plant material shall meet or exceed size and shape relationships specified in the latest edition of The American Standard for Nursery Stock published by the American Association of Nurserymen.
B. Trees
1. Deciduous Canopy Trees
Deciduous canopy trees shall have a minimum size of two-inch caliper at time of planting, unless permitted under paragraph 8.3.1E.3.
2. Evergreen Canopy Trees
Evergreen trees shall have a minimum height of eight feet at the time of planting.
3. Deciduous Understory Trees
a. Deciduous understory trees with single stems shall have at a minimum size of one-inch caliper and a minimum height of eight feet at the time of planting.
b. Multi-stemmed deciduous understory trees shall have a minimum height of eight feet at the time of planting.
4. Evergreen Understory Trees
Evergreen understory trees shall have a minimum height of six feet at the time of planting.
5. Tree Spacing
a. Canopy trees shall be planted at least 18 feet apart.
b. Deciduous understory trees shall be planted at least 12 feet apart.
c. The spacing between canopy and deciduous understory trees shall be at least six feet.
6. Mixing of Tree Species
When more than 10 trees are required to be planted on a site to meet these regulations, a mix of species shall be provided. The following table indicates the maximum percentage of trees of the same genus and species that may be planted:
|
Total Trees Planted on Site |
Minimum Number of Species Required |
Maximum Percentage of Any Species |
|---|---|---|
|
10 trees or less |
1 |
not applicable |
|
11 to 20 trees |
2 |
70% |
|
21 to 50 trees |
3 |
50% |
|
51 to 100 trees |
4 |
40% |
|
101 to 200 trees |
5 |
30% |
|
201 to 300 trees |
6 |
25% |
|
301 to 500 trees |
7 |
20% |
|
Over 500 trees |
8 |
20% |
C. Shrubs
1. Deciduous and Evergreen Shrubs
a. All shrubs shall be cold hardy and heat tolerant.
b. Upright shrubs shall be a minimum of 15 inches in height at the time of planting.
c. Shrubs shall not be planted closer than three feet on center. Shrubs shall not be planted closer than three feet to planted trees, nor within six feet of existing protected trees; however, no more than 25% of the tree protection zone of an existing tree may be disturbed with new plantings.
d. When planted as a hedge, the maximum spacing for 24-inch high shrubs shall be 36 inches on center. Spacing for other size shrubs shall as specified within the Landscape Manual pursuant to paragraph 9.2.1, Landscape Manual.
2. Mixing of Shrub Species
When more than 20 shrubs are required to be planted on a site to meet these regulations, a mix of species shall be provided. The following table indicates the maximum percentage of shrubs of the same genus and species that may be planted.
|
Total Shrubs Planted on Site |
Minimum Number of Species Required |
Maximum Percentage of Any Species |
|---|---|---|
|
21 to 100 shrubs |
4 |
30% |
|
101 to 200 shrubs |
5 |
25% |
|
201 to 300 shrubs |
6 |
20% |
|
301 to 400 shrubs |
7 |
20% |
|
401 to 500 shrubs |
8 |
20% |
|
501 to 600 shrubs |
9 |
20% |
|
Over 601 shrubs |
10 |
20% |
D. Plant Species List
1. A list of plants by type and appropriate location or use to satisfy the requirements under this Article shall be maintained within the Landscape Manual pursuant to paragraph 9.2.1, Landscape Manual.
2. A list of prohibited plants identified as inappropriate for use within Durham City and County shall be maintained within the Landscape Manual. These plants shall not be used to satisfy landscaping requirements, either as existing or proposed plant material.
3. When a species or cultivar is proposed for use but is not listed within the Landscape Manual, a professional urban forester or certified plant professional shall certify that the use of the plant material is appropriate for the intended use and location, and that it does not have invasive tendencies.