In the San Gabriel Valley, whether you can remove, or even heavily trim, a tree in your own backyard depends on which side of a city line the trunk stands on. La Cañada Flintridge, San Marino, Pasadena and South Pasadena each run their own tree-protection framework, and unincorporated areas answer to the county instead. This guide compares the verified rules city by city, and explains the one step that protects you everywhere: checking the rules for your specific address before any work is scheduled.

La Cañada Flintridge: a clear size threshold for oaks and sycamores

La Cañada's rules live in Municipal Code Chapter 11.40. The headline rule is specific and measurable: oak and sycamore trees with a trunk diameter of 12 inches or more are protected, and protected trees require city approval before removal and before pruning that goes beyond routine maintenance. Two practical consequences follow. First, measurement matters. A sycamore just under the threshold and one just over it are in different legal categories. Second, species identification matters, because the protection is written around particular species rather than every large tree in the city. If you are planning work in La Cañada Flintridge, assume the permit question needs a real answer, not a guess, whenever an oak or sycamore is involved.

San Marino: removal permits, and pruning thresholds too

San Marino regulates both directions of tree work. Removing a tree requires a permit. Less widely known: pruning can require one too. A trim that removes more than 10% of an oak, or more than 20% of a heritage tree, crosses into permit territory. That distinction changes how a job should be planned. A heavy reduction that a crew might treat as routine elsewhere can be a permitted action in San Marino, and splitting the work or re-scoping it below the thresholds is a conversation to have before anyone climbs, not after. Our San Marino page summarises how we approach estimates there.

Pasadena: categories, not a single rule

Pasadena's framework, the City Trees and Tree Protection Ordinance (Municipal Code Chapter 8.52), is broader and works by category. It protects native trees (a listed set of species, over 8 inches in trunk diameter), specimen trees (a longer published species list), landmark trees, and mature trees, and it also protects all public trees outright. Which category a tree falls into, and whether protection applies, can depend on the tree's size and its position in the yard as well as the property's zoning. We are describing Pasadena's framework generally here on purpose: the honest answer for a specific Pasadena tree comes from matching its species, diameter and location against the ordinance, address by address. Start with our Pasadena page and the estimate check described below.

Not sure if your tree is protected?

Tell us the address and send a photo of the tree. We check the rules that apply at your address and tell you in writing, with the quote, whether a permit is needed before any work is scheduled.

South Pasadena: mature, heritage, native and oak trees

South Pasadena regulates trees under Municipal Code Chapter 34. The city's published guidance describes protections for mature heritage, native species and oak trees, with oaks covered from 4 inches in diameter, on private property anywhere in the city, and a permit process for removal that generally expects a substantial reason, supporting documentation, and replacement planting as a condition of approval. Trimming protected trees is regulated as well. South Pasadena's ordinance has been updated in recent years and its categories and thresholds have been revised, so verify the current chapter and the city's resident guide before relying on any summary, including this one, for a specific tree.

And if you are not in a city at all?

Altadena and other unincorporated communities answer to Los Angeles County, which has its own oak tree protections and permit process. The pattern is the same as the cities (species, size and location decide), but the permitting office and forms are different. "Unincorporated" does not mean "unregulated," especially for oaks.

What "we check the rules for your address" actually means

At the estimate, the check is mechanical, and you should expect any tree company working in these cities to do it:

  1. Identify the jurisdiction (city or county) from the address, because the same street can cross a boundary.
  2. Identify the species and measure the trunk, because every framework above turns on species plus diameter.
  3. Match the planned work against the thresholds: removal versus pruning, and for pruning, how much of the canopy the work would remove.
  4. Tell you the result before scheduling: no permit needed, permit needed, or permit needed unless the scope changes, and note it on the written quote.

If a permit is required, the work waits for it. Removing a protected tree without approval can mean fines and required replacement planting, and it can complicate a property sale later. The permit step is a small delay next to that. Our tree removal page explains how removals are scoped once the permit question is answered.

Ordinance summaries consulted October 2026: La Cañada Flintridge Municipal Code Chapter 11.40; San Marino tree permit rules; Pasadena Municipal Code Chapter 8.52 and the City of Pasadena Urban Forestry pages; South Pasadena Municipal Code Chapter 34 and the city's resident tree-ordinance guide. Ordinances change. The check at your estimate uses the rules in force at that time.