Local deciduous oaks have roughly oval-shaped, shallow to deeply lobed leaves. Leaves vary greatly in size, even on the same tree and within the same species. Oaks will also hybridize, so ID can be tricky.

Stewardship Considerations

Identifying oak species will help determine proper pruning, as species vary widely in their mature height, growth rate and growth pattern. A small scrub oak or Blue oak might be decades old, and heavy thinning and/or improper pruning could damage an entire grove and ecosystem. Oaks are generally slow-growing and long-lived trees. Larger trees grow more slowly and are less tolerant of pruning.

When pruning oaks, remember that “less is more.” Avoid removing large branches (over 4” diameter). If a large branch needs pruning, consider shortening rather than removing it, cutting it back to lateral branches that are 1/3–1/2 of the diameter of the branch they are being removed from.

No more than 25% of crown growth should be removed during the annual growing season. Excessive pruning can lead to sunburn injury and dieback.

Oaks will stump-sprout.

Bottom left: Poor pruning that cut into heartwood.

Bottom left center: An overly large branch was removed from this Oregon oak, but it healed well, partly due to proper pruning techniques.

Bottom center: Improper pruning on Blue oak, with stubs not removed.

Bottom right center: Valley oak leaves.

Bottom right: Excessive pruning resulted in unhealthy epicormic (dormant-bud) growth.

Print this ID Card

Learn more about oaks from the California Native Plant Society