Sidewalk & Basin Care
The tree basin is the square – or rectangle – that is cut out of the sidewalk.
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Sidewalk level should be equal to soil and mulch level.
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Mulch should be about 3" deep and not around the trunk.
If you need to add soil, it’s best to add natural soil from the immediate area rather than to buy soil. (see the soil section to find out why)
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Don’t raise the soil around your tree trunk! It can cause rot and kill the tree. If you must build a raised box around the tree, keep the tree trunk at a separate level from the raised part. Do this with a large tube or barrier around the trunk, with plenty of airspace, inside the box. Make sure there is room for the tree to grow!
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If you plant in the basin, wait a few months until the tree is established. Do not plant ivy or other aggressive plants. See the soil section for suggested plants.
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If you must add bricks, or stones, do not mortar them in! The tree needs the water and oxygen. It won’t help control roots. Consider only a border of flat bricks, rather than all around the tree.
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As a last resort, even weeds are better than bare dirt! If kept under control, they can act as natural mulch, trapping moisture and preventing soil runoff.
Keep plants short and away from the trunk.
Legal Notes:
City code requires that you apply for a minor encroachment permit for anything that sticks up around the border of a tree basin. This includes benches, bollards (large concrete poles), fences, planter boxes, etc. The edging treatment must be at least 6 inches and no more than 15 inches high from the grade of the sidewalk and allow water to flow around or through into the landscape (tree basin). It may be made of wood, stone, decorative metal or other material, subject to staff review. For more information call DPW Bureau of Urban Forestry, 641-2676.
Expansion of the tree basin to accommodate roots or to plant additional plants may require a minor encroachment permit. Please check with the DPW Bureau of Street Use and Mapping, 554-5810 before doing so.
Help! My sidewalk is cracking! What do I do?
The easiest thing to do is to expand the tree basin to accommodate the roots. American Disabilities Act requires that the sidewalk be 4 feet wide in a straight line to allow passage of wheelchairs. If your sidewalk is wide enough, you may be able to expand the basin. For more information visit Plant SF's site and DPW's site.
If you can’t expand the tree basin, there are three steps:
- Remove the affected concrete.
- Have the tree root pruned by an arborist. This is not a job for a novice. The idea is to prune the roots without adversely affecting the stability and health of the tree.
- Replace the concrete.
For referrals, see: arborist referral
