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1. Assemble the materials and tools
15-gallon tree
36" x 36" basin in sidewalk
Two 8-foot wood stakes, 2 inches in diameter
Two or Three 30-inch rubber ties
Six 10-penny galvanized nails
One 4-inch diameter deep-watering tube, 2 feet long (cardboard or perforated PVC pipe)
Gravel (approximately 4 cups)
Shovel and pick-ax
Hammer
Stake Pounder (this can be rented from the FUF office)
Hand pruners
Garden hose and watering bucket
Wire-mesh screening, if needed
Water-absorbing polymers, if needed
Optional basin covering (mulch, gravel, paving stones, or bricks)
- Remove soil until your planting hole is twice the
width of the rootball.
- With a shovel, roughen up the sides and bottom of the hole -- especially in compacted clay soils, since smooth sides can act as a barrier to root growth.
- Place the watering tube vertically in the corner of the basin, on the uphill curb side. The top of the tube should be even with the sidewalk surface.
- Use a crossbrace to measure the height of your tree's rootball Fill the bottom of the hole with excavated soil, tamping down the soil as you go, until your planting hole is the same depth as the rootball's height (usually about 18 inches). If your soil type calls for it, add water-absorbing polymers or a non-ionic surfactant to the soil as you fill.
- To get an accurate depth measurement, lay a stake across the planting hole and use a crossbrace to measure from the stake down to the center of the hole. The hole should be as deep as the rootball is high. It is important that the tree be planted even with the level of the sidewalk. If it is planted either too deep or too shallow, it will not thrive and may die.
- Tamp the soil down firmly to ensure that the tree will not settle after planting.
- If you are using a root barrier, curve it into as large a circle as possible, ribbed side facing inward, and place it in the hole so the top is 1 inch above the level of the sidewalk. This prevents surface roots from growing over the barrier. Place the watering tube outside of the root barrier. (Root barriers, usually made of rigid plastic, are used to protect sidewalks and sewers from invasive tree roots. Their effectiveness is still being studied. Some arborists claim they inhibit normal root growth, causing tree instability.)
- Inspect your tree. Prune off any broken limbs. With a hand pruners, thin upper branches if they are very bushy, to allow wind to pass through the tree. Lower branches that will not interfere with pedestrians should be left on the tree as they help the tree to develop a strong trunk. These lower branches should be gradually pruned off in later years so they don't develop into major branches.
- Before removing the tree from the container, tap the container with the side of a hammer to loosen the tree. Then, tip the tree about 45 degrees, hold on to the trunk and nursery stake near the base, and pull the container off If the tree will not come easily out of the container, cut the container from the rim downwards with hand pruners, being careful not to cut the roots.
- As you remove the container, set the rootball on a shovel to support its weight. Always lift the tree by the container or with a shovel under the rootball -- do not lift the tree by the trunk, as this will damage the roots.
- While the rootball is exposed and resting on the shovel, inspect for circling or kinked roots. Loosen these roots with your finge
rs. If they are too ingrown to be separated by hand, or too long to fit in the planting hole, prune them lightly.
- Still supporting the rootball with the shovel, place the tree in the prepared hole. Make sure the tree is centered. Turn the tree so the majority of its leaf growth faces into the wind. This will help the tree develop a balanced shape.
- Before backfilling the hole, lay a stake over the planting hole to double-check that the tree is planted at the correct depth -- the top of the rootball should be perfectly flush with the sidewalk or brick paving.
- Make any necessary adjustments by adding or removing soil beneath the tree while supporting the rootball with a shovel. Correct planting depth is critical to long-term tree survival. if the tree is planted too deep, water and Soil will collect around the trunk, causing rot and eventual tree death. If it's planted too high, the roots will be exposed and will dry out.
5. Backfilling the Planting Hole
- Add soil to fill in around the rootball and watering tube, tamping down firmly as you go. Make sure that no soil gathers around the trunk of the tree. The top of the rootball should be just visible on the surface after the native soil has been backfilled around it.
- Make sure the watering tube is flush with the sidewalk to avoid creating a tripping hazard.
- Fill the watering tube with gravel. Over time, the cardboard tube will decompose and the gravel watering channel will remain.
6. Placing Stakes and Crossbraces
- Remove any nursery stakes or ties. If left on, these can damage the tree by rubbing wounds in the bark or becoming embedded in the tree as it grows.
- Drive support stakes at least 2 feet into the ground using a stakepounder or sledgehammer. Place stakes about eighteen inches apart, making sure they do not penetrate the rootball. Use a crossbrace to measure the distance between the stakes.
- Attach the crossbrace to the stakes at about shoulder height, adjusting the placement to avoid branches. Use two nails on each side. It is easier to start nails into the crossbrace when it is laying on the ground.
- Secure the tree by loosely looping a rubber tie, in a figure-eight, between each stake and the trunk. Attach the ties to the stakes with nails. Don't hammer the nails all the way in because the ties will need to be adjusted as the tree grows.
- Leave room for the tree to move in the wind. Movement is exercise for the tree and will help it develop a strong trunk.
- The upper tie should be supporting the tree against the direction of the prevailing wind. The lower tie should be at the level of the crossbrace, to prevent the tree from rubbing against the brace. If the tree is top-heavy or has a thin trunk, add a third tie where needed to prevent the tree from leaning. Thinning the crown may also help.
8. Installing Protective Screening
In commercial areas, near schools, and in other areas that experience heavy pedestrian traffic, tress are vulnerable to accidental damage and vandalism. FUF recommends installing protective wire-mesh screening, also called hardware cloth, around trees in these areas. The screening helps to deter vandals and deflect hazards such as car doors, and can give a young tree an important advantage during its first few years. It is important, however, to remove the screening as soon as the tree has grown large enough to make the protection unnecessary -- usually two to four years after planting. Screens that are left on too long can inhibit healthy tree growth and wound trees by rubbing against them.
- Wrap a 4-by-5-foot sheet of screening around the tree, overlapping the edges by about 2 inches. Leave about 2 feet of clearance between the basin and the bottom of the screening.
- Attach the screening to both stakes with nails. Bend the screen down wherever branches might rub against the hard edges of the wire mesh as they move in the wind.
- Use your hands to shape a watering berm: a 2-inch high wall of soil around the basin, as close to the edge of the basin as possible. The berm is especially important on the downhill side of the slope, where it catches water run-off and holds it until it can soak into the ground.
- On hilly sites, use pieces of brick or broken concrete around the edge to form a stronger berm, but be careflil not to create a tripping hazard.
- Lay a hose inside the berm and fill the berm with water. Soak the tree basin for 30 minutes at a slow drip, avoiding run-off.
- FUF recommends that you cover the surface of the basin outside the watering berm with a mulch (such as fir bark or gravel), irregular paving stones, or loosely fitting bricks. Covering the basin helps retain moisture in the soil and minimizes weed growth and trash in your tree basin. It also reduces erosion, and helps protect and insulate the roots. All paving materials should be set with sand (not cement!) to let water and air penetrate the surface of the root zone.
- If you are using bricks, set them with wet sand and lay them in a regular pattern around the basin, making sure to leave at least an 8-inch square space unpaved around the trunk for the watering berm. Bricks should not protrude above sidewalk level, where they would pose a tripping hazard.
- In general, FUF discourages planting anything more than a tree in a tree basin. Perennial grasses, shrubs, and deep-rooted groundcovers will compete with your tree for precious water and nutrients. Some groundcovers, such as ivy or morning glory, will strangle trees. If you want to plant flowers in your tree basin, choose only shallow-rooted annuals.
- Finally, clean up your planting site and dispose of all excess planting materials properly.