5.1 Plant Bed Preparation (Before Planting)
▶ Excavation: to the proposed subgrade for all planting areas. Do not over excavate the compacted subgrades of adjacent pavement or structures. Maintain a supporting 1:1 (45-degree) side slope of compacted subgrade material along the edges of all paving and structures where the bottom of the paving or structure is above the bottom elevation of the excavated planting area.
▶ Scarification: In areas where Planting Soil is to be spread above existing subsoil, scarify the subgrade material. Scarify the subsoil of the subgrade to a depth of 3–6 inches with the teeth of the back hoe or loader bucket, tiller or other suitable device. Protect the loosened area from traffic and immediately install the Planting Soil. Do not allow the loosened subgrade to become compacted.
▶ Grading: Confirm that the subgrade is at the proper elevation and is compacted as required. Subgrade elevations shall slope approximately parallel to the finished grade and/or toward the subsurface drain lines. Provide for positive drainage from all areas toward the existing inlets, drainage structures, and/or the edges of planting beds. Fill all dips and remove any bumps in the overall plane of the slope. Utilize hand equipment, small garden tractors with rakes, or small garden tractors with buckets with teeth for fine grading to keep surface rough without further compaction.
▶ Install Planting Soil: See 2.6 for instructions.
▶ Installation of Compost: After Planting Soil Mixes are installed in planting bed areas, and just prior to the installation of shrub or groundcover plantings, spread 3–4 inches of Compost over the beds and roto till into the top 4-6 inches of the Planting Soil. This step will raise grades slightly above the grades required, but it is anticipated that the raise in grade due to this tilling will settle within a few months after installation as the Compost breaks down.
▶ Protection: Protect adjacent walls, walks and utilities from damage or staining by the soil. You may use 1/2 inch plywood and or plastic sheeting to cover existing concrete, metal and masonry work and other items as directed during the progress of the work. At the end of each working day, clean up any soil or dirt spilled on any paved surface. Where travel over the installed soil is unavoidable, limit the paths of traffic to reduce the impact of compaction in the Planting Soil.
5.2 Plant Bed Planting (During Planting)
▶ Instructions: Observe each plant prior to installation for damage, or other characteristics that may cause rejection of the plant. No more plants should be distributed about the planting bed area than can be planted and watered on the same day. The root system of each plant, regardless of root ball package type, shall be observed by you or your contractor at the time of planting to confirm that the roots meet the requirements for plant root quality (see x.x). Your or your contractor should undertake prior to the time of planting, all modifications to the root system required to meet these quality standards. Confirm that the grower has made any root modifications that have been noted during observations at the nursery. The resulting root ball after modification may need additional staking and water after planting. Make sure that you are aware of what is covered under warranty for your plants. You may be able to reject plants if the root modification process makes the tree unstable or if the tree is not healthy at the end of the warranty period.
▶ Container and Boxed Root Ball Shaving: The outer surfaces of all plants in containers and boxes, including the top, sides, and bottom of the root ball shall be shaved to remove all circling, descending, and matted roots. Shaving shall be performed using saws, knives, sharp shovels or other suitable equipment that is capable of making clean cuts on the roots. Shaving shall remove a minimum of one inch of root mat, or up to 2 inches as required to remove all root segments that are not growing reasonably radial to the trunk.
▶ Exposed Stem Tissue after Modification: The required root ball modifications may result in stem tissue that has not formed trunk bark being exposed above the soil line. If such condition occurs, wrap the exposed portion of the stem in a protective wrapping with a white filter fabric. Secure the fabric with biodegradable masking tape. DO NOT USE string, twine, green nursery ties or any other material that may girdle the trunk if not removed.
▶ Excavation of the Planting Space: Using hand tools or tracked mini-excavator, excavate the planting hole into the Planting Soil to the depth of the root ball measured after any root ball modification to correct root problems, and wide enough for working room around the root ball or to the size indicated on the drawing or as noted below. For trees and shrubs planted in soil areas that are NOT tilled or otherwise modified to a depth of at least 12 inches over a distance of more than 10 feet radius from each tree, or 5 feet radius from each shrub, the soil around the root ball shall be loosened as defined below or as indicated on the drawings. The area of loosening shall be a minimum of 3 times the diameter of the root ball at the surface sloping to 2 times the diameter of the root ball at the depth of the root ball. Loosening is defined as digging into the soil and turning the soil to reduce the compaction. The soil does not have to be removed from the hole, just dug, lifted and turned. Lifting and turning may be accomplished with a tracked mini excavator, or hand shovels. If an auger is used to dig the initial planting hole, the soil around the auger hole shall be loosened as defined above for trees and shrubs planted in soil areas that are NOT tilled or otherwise modified. The measuring point for root ball depth shall be the average height of the outer edge of the root ball after any required root ball modification. If motorized equipment is used to deliver plants to the planting area over exposed planting beds, or used to loosen the soil or dig the planting holes, all soil that has been driven over shall be tilled to a depth of 6 inches.
▶ Plant Placement: For trees to be planted in prepared Planting Soil that is deeper than the root ball depth, compact the soil under the root ball using a mechanical tamper to assure a firm bedding for the root ball. If there is more than 12 inches of planting soil under the root ball excavate and tamp the planting soil in lifts not to exceed 12 inches. Set top outer edge of the root ball at the average elevation of the proposed finish. Set the plant plumb and upright in the center of the planting hole. The tree graft, if applicable, shall be visible above the grade. Do not place soil on top of the root ball. The Owner’s Representative may request that plants orientation be rotated when planted based on the form of the plant.
▶ Backfilling: Backfill the space around the root ball with the same planting soil or existing soil that was excavated for the planting space. See Specification Section Planting Soil, for requirements to modify the soil within the planting bed. Brace root ball by tamping Planting Soil around the lower portion of the root ball. Place additional Planting Soil around base and sides of ball in six-inch (6") lifts. Lightly tamp each lift using foot pressure or hand tools to settle backfill, support the tree and eliminate voids. DO NOT over compact the backfill or use mechanical or pneumatic tamping equipment. Over compaction shall be defined as greater than 85% of maximum dry density, standard proctor or greater than 250 psi as measured by a cone penetrometer when the volumetric soil moisture is lower than field capacity. When the planting hole has been backfilled to three quarters of its depth, water shall be poured around the root ball and allowed to soak into the soil to settle the soil. Do not flood the planting space. If the soil is above field capacity, allow the soil to drain to below field capacity before finishing the planting. Air pockets shall be eliminated and backfill continued until the planting soil is brought to grade level. Where indicated on the drawings, build a 4 inch high, level berm of Planting Soil around the outside of the root ball to retain water. Tamp the berm to reduce leaking and erosion of the saucer.
▶ Finishing: Thoroughly water the Planting Soil and root ball immediately after planting. Remove all nursery plant identification tags and ribbons as per Owner’s Representative instructions. The Owner’s Representative’s seals are to remain on plants until the end of the warranty period. Remove corrugated cardboard trunk protection after planting. Follow additional requirements for the permitted root ball packages (see x.x).
5.3 Plant Bed Finishing (After Planting)
▶ 1. Define Plant Beds: Smooth out all grades between plants before mulching. Separate the edges of your planting beds and lawn areas with a smooth, formed edge cut into the turf with the bed mulch level slightly lower than the adjacent turf sod by 1 or 2 inches . The plant bed edge lines are depicted in the Landscape Design.
▶ 2. Mulch Plant Beds: Apply 4 inches of mulch before settlement, covering the entire planting bed area. Install no more than 1 inch of mulch over the top of the root balls of all plants. Taper to 2 inches wherever the mulched area abuts pavement. For trees planted in lawn areas, the mulch should extend somewhere between a 2-3 foot radius around the tree, or to the extent indicated on the plans (if shown). Lift all leaves, low hanging stems, and other green portions of small plants out of the mulch if they are covered.
▶ 3. Watering Plant Beds: Ensure that adequate water is provided to all plants from the point of installation, to at least 90 days after installation. You or your contractor should adjust the automatic irrigation system, if available, and apply additional or adjust for less water using hoses if needed. Hand water the root balls of all plants to assure that the root balls have moisture above wilt point, and below field capacity. You or your contractor should install one 25-gallon watering bag for each tree to be maintained and used for tree watering.
5.4 Pruning New Trees and Shrubs
▶ Instructions: Pruning trees should be limited to addressing structural defects (see x.x). Except for plants specified as multi-stemmed, preserve or create a central leader. Pruning large trees should be done using pole pruners or if needed, from a ladder or hydraulic lift to gain access to the top of the tree. Do not climb in newly planted trees. Small trees can be structurally pruned by laying them over before planting. Pruning may also be performed at the nursery; there should be someone who can assist in pruning it, or provide you with additional guidance. Pruning shall be done with clean, sharp tools and no tree paint or sealants should be used.
5.5 Staking and Guying
▶ Instructions: Do not stake or guy trees unless it is specifically called out on the landscape plan, or in the event that you or your contractor feels that staking is the only alternative way to keep a particular tree plumb. Tree guying shall utilize the tree staking and guying materials specified (see x.x). Stakes should be driven to a sufficient depth to hold the tree rigid and plumb, and guying should be tied in such a manner as to create a minimum 12-inch loop to prevent girdling. Remove the guys and stakes after one full growing season.
5.6 First Growing Season Procedures
▶ Instructions: Once your plants are planted in After planting, you will want to make sure that all new plants are maintained in a plumb position throughout the first growing season. If any plants move out of plumb, plants to be straightened should be excavated and the rootball moved into a plumb position and backfilled. Controlled release fertilizers should be applied according to the manufacturer’s instructions and standard horticultural practices. Remove any guys and stakes from your plants after one full growing season.
5 Plant Beds