Blue Oak
Quercus douglasii
Fagaceae · broadleaf deciduous tree · introduced
Last updated
Plant Profile
Size & Form
Height
60 ft
Spread
40-50 ft
Growth Rate
Slow
Size at 20 yr
16 ft
Lifespan
Long-lived
Site Requirements
Light
Full Sun
Soil Drainage
Well Drained
Soil pH
4.5-7.5
Water
Low
Drought Tolerance
High
Hardiness
Zones 8a–8b
Ornamental Interest
Bloom Time
spring
Fall Color
Orange, pink, yellow
Origin
the dry woodlands and valleys around the California's
Watch for this season
Cytospora CankerHigh
Peak Spore Production and Dispersal
Powdery MildewHigh
Active Conidial Spread
Anthracnose (Shade Trees)Moderate
Active Infection & Secondary Spread
Armillaria Root RotModerate
Active Below-ground Growth
+ 3 more — see full disease and pest lists below
Diseases: Regionally Documented (13)
Ramorum Blight (Sudden Oak Death) Mistletoe Armillaria spp. — primarily A Armillaria Root Rot Discula destructiva (dogwood), Kabatiella and Discula spp... Anthracnose Cytospora spp. (Valsa spp., Leucostoma spp.) Cytospora Canker Microstroma album Frosty Mildew Ganoderma applanatum Ganoderma Root and Butt Rot Pseudoinonotus dryadeus Inonotus Root and Butt Rot Taphrina spp. Leaf Blister Phoradendron villosum Mistletoe (a True Mistletoe) Neonectria ditissima Nectria Canker Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Inonotus dryophilus White Pocket Rot (Piped Rot)
Pests: Regionally Documented (14)
Looper Stem Gall Asterolecanium spp. Pit scale Platycotis vittata Oak Treehoppers Bucculatrix albertiella Oak Ribbed Casemaker Phylloxera spp. Oak leaf phylloxera Various (Cynipidae, Cecidomyiidae, Eriophyidae, Psyllidae) Leaf galls Neuroterus saltatorius Jumping Oak Gall Andricus quercuscalifornicus California Gallfly Prionoxystus robiniae Carpenterworm Oak gall wasp Bucculatrix ainsliella Oak skeletonizer Edwardsiana rosae Rose leafhopper Various (Cynipidae, Cecidomyiidae, Eriophyidae) Leaf and twig gall
Phenological Calendar
View full calendar (8 stages)
| Stage | Typical Window |
|---|---|
| Bud break BBCH 07 | Feb 15-Mar 15 |
| Leaf emergence BBCH 11 | Mar 1-Apr 1 |
| Bloom start BBCH 61 | Mar 15-May 15 |
| Bloom end / petal fall BBCH 69 | Apr 15-May 31 |
| Fruit/seed development BBCH 71 | Jun 1-Aug 31 |
| Fruit/seed maturity BBCH 85 | Sep 1-Nov 30 |
| Fall color / leaf senescence BBCH 93 | Oct 1-Nov 15 |
| Dormancy BBCH 97 | Nov 15-Feb 28 |
Data Maturity Structured Multiple sources. Expert review underway.