blue oak
Quercus douglasii · Fagaceae
blue oak (Quercus douglasii) is a perennial tree in the Fagaceae family. It is native to North America. USDA records it as hardy in zone 8 and warmer, down to about 10°F.
At a glance
| Type | tree USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 60 ft USDA |
| Light | full-sun USDA |
| Water need | low USDA |
| Growth rate | slow USDA |
| Soil pH | 4.5–7.5 USDA |
| Bloom | March–May USDA |
| Flower color | Yellow USDA |
| Hardiness zones | 8 and warmer USDA |
| Guild layer | canopy Derived |
| Nursery availability | Contracting Only USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It needs full sun. USDA rates it as having low water needs once established. Its drought tolerance is rated high. It will not tolerate waterlogged soil — USDA rates its anaerobic tolerance as none. It is recorded on soils from pH 4.5 to 7.5 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 8.
Size and growth
At maturity it reaches about 60 ft, making it a large tree that will dominate its site. It grows slowly.
Bloom period
USDA records a bloom period of March through May. Flowers are yellow.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is gray-green, coarse in texture. Its flowers are not conspicuous — a plant for form and foliage. It carries conspicuous autumn colour. Its fruit or seed heads are conspicuous, extending interest past flowering. Its active growth period is spring. USDA rates its lifespan as long.
What the site needs to provide
USDA records it across sites receiving 10 to 60 inches of annual precipitation. The low end of that band is genuinely arid, so it has a wide tolerance for dry country. It needs at least 150 frost-free days to finish its season. It roots to at least 32 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
Propagate it from seed, bare root and container stock. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a slow rate. It spreads vegetatively at a slow rate.
Resilience and wildlife
Browsing animals rate it barely palatable — the sourced basis for calling it deer-resistant. Its fire tolerance is rated low, and it can resprout after damage. Its growth form is recorded as single stem.
Role in a guild
Canopy. In a layered planting this is the tallest layer of a planting — it sets the light budget everything beneath it lives on. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Quercus
- sawtooth oak Quercus acutissima
- California live oak Quercus agrifolia
- white oak Quercus alba
- swamp white oak Quercus bicolor
Similar role and hardiness
- Pacific madrone Arbutus menziesii
- Coulter pine Pinus coulteri
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol QUDO, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, browse palatability, cold stratification, Drought tolerance, Edible, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
Find more plants for your zone with the Plant Finder.