# Blue Oak (Quercus douglasii)

> Blue oak, Quercus douglasii: a medium tree of 20 to 80 feet where planted, for zones 6 to 9, how fast it grows, and the natives we grow for the same ground.

Blue Whale Trees, a native tree nursery in the United States. Web version: https://bluewhaletrees.com/species/blue-oak/

![A large blue oak with a broad, rounded crown standing alone on dry golden grass](https://bluewhaletrees.com/img/species/blue-oak-1000.jpg?v=3eab2970 "A mature blue oak at Stanford Dish Park, California, on June 21, 2026. The oldest dated by its rings, a dead tree at Los Lobos Creek, was at least 553 years old.")
*Photo: Awinch1001, [CC0](https://creativecommons.org/publicdomain/zero/1.0/deed.en) ([source](https://commons.wikimedia.org/wiki/File%3AQuercus_douglasii_Tree_Stanford_Dish_Park.jpg))*

Medium tree, 20 to 80 feet where planted, zones 6 to 9; full sun or part shade; dry or average ground.

We do not grow blue oak, and it is not in our shop. This page gathers what our tools say about it and the natives we grow for the same ground.

## At a glance

| Fact | Blue Oak |
| --- | --- |
| Other names | Mountain white oak, mountain oak, California blue oak |
| Form | Medium tree |
| Height, feet | 20 to 80 where planted; up to 94 in its native stands |
| Spread, feet | Up to 50 |
| Zones | 6 to 9 |
| Sun | Full sun or part shade |
| Soil moisture | Dry or average ground |
| Growth | Slow |
| Leaves | Deciduous |
| Traits | Fall color, wildlife value, edible, erosion control |
| Flowers | March to May |
| Fruit | Acorns, September to October |
| Pollination | Needs a second, unrelated tree. The flowers are wind pollinated. A blue oak is rarely self fertile, so an acorn crop wants another blue oak nearby. |
| Lifespan | The oldest tree dated by its rings was at least 553 years. Only a tiny share of trees has ever been ring-counted or cross-dated. |
| Planting season | Fall. University of California Agriculture and Natural Resources plants seedlings by the end of January, best in mid-December, as March is usually too late. The NRCS plant guide plants in winter. |
| Black walnut | Not named on the Morton Arboretum's lists |
| Ground | Dry uplands and rocky ground |
| Native in | 1 state |

Blue oak is native in 1 state: [California](https://bluewhaletrees.com/tools/native/index.html.md?state=CA). The states are the USDA PLANTS Database's records, with the native range read from Silvics of North America and the Fire Effects Information System.

## What our tools say

- [How fast it grows and how big it gets, by site](https://bluewhaletrees.com/tools/growth/index.html.md?species=blue-oak): the growth estimator
- [Whether it suits your zone, sun and soil](https://bluewhaletrees.com/tools/site-check/index.html.md?species=blue-oak): the planting-site check
- [How far from a house, wires and a septic field](https://bluewhaletrees.com/tools/distance/index.html.md?species=blue-oak&near=house,septic,pavement,wires,boundary,tree): the planting-distance tool
- [What grows with it in the wild and in a yard](https://bluewhaletrees.com/tools/companions/index.html.md?species=blue-oak): the companion species tool
- [When to plant it where you live](https://bluewhaletrees.com/tools/planting-window/index.html.md?species=blue-oak): the planting-window tool
- [When it flowers and fruits, month by month](https://bluewhaletrees.com/tools/calendar/index.html.md?plants=blue-oak): the bloom and fruit calendar
- [How to sow its seed, with dates for your place](https://bluewhaletrees.com/tools/sowing/index.html.md?species=blue-oak): the seed sowing planner
- [How many to plant for a crop of seed](https://bluewhaletrees.com/tools/pollination/index.html.md?plants=blue-oak:2): the pollination planner
- [Whether one you have can be moved, and what the move takes](https://bluewhaletrees.com/tools/transplant/index.html.md?species=blue-oak): the transplant planner
- [How old one is, from its trunk](https://bluewhaletrees.com/tools/tree-age/index.html.md?species=blue-oak): the tree age calculator
- [How a big one scores against the champion trees](https://bluewhaletrees.com/tools/big-tree/index.html.md?species=blue-oak): the big-tree measurer

## For the same ground, we grow

- [Chokecherry](https://bluewhaletrees.com/plants/chokecherry/index.html.md) (*Prunus virginiana*): small tree, 20 to 30 feet, zones 2 to 10. Shares rocky ground in the wild.
- [More natives for this ground in the tree finder](https://bluewhaletrees.com/tools/tree-finder/index.html.md?size=medium-tree&sun=full&moisture=average)
- [Every companion of blue oak in the companion species tool](https://bluewhaletrees.com/tools/companions/index.html.md?species=blue-oak)

## Read from

Its figures come from Silvics of North America, the Forest Service's Fire Effects Information System, the Woody Plant Seed Manual, the USDA PLANTS Database, Oregon State University's Landscape Plants, Cal Poly's SelecTree, the Wildflower Center, Calscape, the UC Davis Arboretum, the Jepson eFlora, University of California Agriculture and Natural Resources, the Native Plant Network and Earth Interactions.