WATER All trees need water to thrive, even drought tolerant trees. Water young trees once or twice a week, and water mature trees monthly or bi-monthly, particularly during hot, dry weather. Be sure to water trees deeply (the top 12+ inches should be wet) and water away from the trunk.
Established native California oaks (Quercus lobata and Q. agrifolia) should not be watered in the warm summer months
PROTECT TREE TRUNKS Mechanical damage from mowers or string trimmers can cause serious damage, especially to young trees. Wounds are easily invaded by disease-causing pathogens and insects. Keep turf away from the base of trees. Also, take care when opening car doors near trees and do not lock bikes to trees.
REDUCE SOIL COMPACTION Trees grow best in uncompacted soil with about 50% pore space (for air and water). Porous soil has better drainage and oxygen flow, and promotes root growth. Avoid driving and parking on the root zone of a tree. Vehicles, heavy machinery, or materials should not be stored beneath a tree.
REMOVE CONCRETE, PAVERS, ETC.* Asphalt and concrete prevent water and air from reaching roots and increase the temperature of the soil and the air around the tree. “Permeable” pavers are slightly better, but soil needs to be compacted for paver installation which damages roots and reduces soil pore space.
*No new paving (concrete, asphalt, pavers, etc.) is permitted within 10 feet of a public tree (PAMC 8.04.020).
REMOVE IVY, WEEDS, AND OTEHR COMPETITIVE PLANTS Vigorous plants like English ivy, weeds, and even turf compete with trees for water, nutrients, and rooting space and should be removed from around trees. Ivy and other climbing plants can conceal defects on trees, can break branches from the weight of the vines, and heavy growth can limit a tree’s photosynthesis by shading the tree.
CALL TO ATTENTION ANY CHANGE IN TREE HEALTH Report insects, diseases, damage, illegal pruning, etc. by calling (650) 496-5953, so we can address the issue(s) in a timely manner.
Public Works Urban Forestry Section Phone: (650) 496-5953 firstname.lastname@example.org P.O. Box 10250 Palo Alto, CA 94303
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