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Big City, Big Trees
Tree Bed Guards
There are many different types of tree guards. The conditions of each tree and tree bed as well as your priorities will dictate which guard is right for a given situation. Also keep in mind that what follow are simply recommendations, and in the end, you are accountable for any tree guard you install. Although the City will not ticket you for installing tree guards, there is no official permit to sanction their construction, so you are responsible for the safety of the guard. The Department of Parks and Recreation may fine you if it determines that your guard is endangering the health of the tree.
Design Recommendations
- Install a guard at the outermost edge of the tree bed to give the tree the most room to grow (at least 24 inches from the trunk of the tree). As the tree matures, monitor the guard so it never constricts the growth of the tree.
- The guard should be tall enough to avoid being a tripping hazard—generally 18 to 22 inches high is adequate.
- The guard should be three- or four-sided (the side closest to the street is often left open so that car doors can open freely).
- The guard should be of a sturdy material. Wrought iron is an excellent choice, but it can be quite costly. Less expensive alternatives include wood and steel.
- The guard should be constructed of openwork rather than solid walls to allow air to circulate and water to drain out. An open guard also prevents the level of the soil from building up too high, which might injure or kill the tree.
- Your street tree bed may have one or more courses of block pavers installed, with the outermost course grouted together. This is required to reduce tripping hazard. The City does not remove these blocks as the tree grows, though you may remove them if they are obstructing the tree's growth.
Inexpensive Tree Guards
Wrought iron tree guards are elegant and durable, but they are also expensive to install and costly to repair. We've seen a lot of creative, low-cost tree guards while judging for the annual "Greenest Block in Brooklyn" contest. Here are two interesting and inexpensive guards that we've seen:
Post and Chain
Drill a hole through one end of each of four sturdy wooden stakes or lengths of pipe. Drive one stake or pipe in each corner of the tree bed, then loop rope or chain through them.
Log Cabin
Stack pieces of wood alternately as if making a small log cabin, being careful not to "wall in" all four sides of the bed. Drill down through each corner, then drive a length of rebar through the holes and into the soil to stabilize the guard.
Tree Guard No-No's
- Do not pave over any part of the tree bed.
- Do not build a solid wall around the bed that prevents water from flowing into it from the sidewalk or soil to build up within.
- Don't use tree grates (metal grates over the tree bed opening).
- Do not attach the guard to the tree.