Valley Oak is one of the largest oak trees in North America and is native to the foothills and valleys of California. It can grow to 100 feet or more and live 600 years. It is very majestic looking with its large wide-spreading branches, massive trunk up to 10 feet in diameter and round spreading crown. With age, the branches can touch the ground. Valley Oak grows in deep fertile soils in hot dry climates but needs access to groundwater and prefers full sun. It is closely related to the Eastern White Oak that is a better choice for the NC area. It is a host plant for the larvae of the Imperial moth ( Eacles imperialis ) , as well as numerous butterflies, including Banded hairstreak ( Satyrium calanus ) , Edward's hairstreak ( Satyrium edwardsii ) , Gray hairstreak ( Strymon melinus ) , White-m hairstreak ( Parrhasius malbum ) , Horace's duskywing ( Erynnis horatius ) , and Juvenalis duskywing ( Erynnis juvenalis ) .
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
High Organic Matter; Loam (Silt)
Soil pH
Acid (<6.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Moist | Occasionally Dry
Mature size
Height: 50 ft. 0 in. - 70 ft. 0 in. | Width: 30 ft. 0 in. - 50 ft. 0 in.
Growth rate
Medium
Maintenance
Medium
Canopy layer
1 - Canopy (>40 ft)
Form & Appearance
Habit / form
Broad; Erect; Rounded; Spreading; Weeping
Texture
Medium
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Elliptical; Obovate
Leaf margin
Lobed
Leaf feel
Soft
Leaf value
Fragrant
Leaf size
3-6 inches long, 1-3 inches wide
Hairs present
Yes
Leaf detail
2-4 inch long and 1-2 inches wide leaves with 6-10 deep lobes are green with pale undersides. The undersides have fuzzy hairs. The base is wedge-shaped, rounded-gradually tapered, or truncate. The tip is obtuse to rounded. The leaves are aromatic when crushed.
Fall color
Brown/Copper; Gold/Yellow
Flower form
Catkin; Insignificant
Flower size
< 1 inch
Flower detail
Monoecious male and female flowers on the same tree. Blooms March to April.
Bloom time
Spring
Fruit type
Nut
Fruit size
1-3 inches long, < 1 inch wide
Fruit detail
The acorn cups are composed of thick, tubercled scales. The elongated nuts are 1-2 inches long, pointed and mature in one year Aug.- Oct.
Bark color
Dark Gray
Bark detail
The mature bark is gray, scaly, and often vertically fissured in a checker-like pattern.
Stem color
Gold/Yellow; Gray/Silver; Red/Burgundy
Stem detail
The twigs are yellowish-grey, sometimes reddish, slightly tomentose. Buds are pale brown, ovoid, 1-2 inches long, pointed, densely pubescent.
Wildlife & Ecology
Native status
Unknown
Origin
California
Distribution
California
Wildlife value
Oak trees support a wide variety of Lepidopteran. You may see Imperial Moth (Eacles imperialis) larvae which have one brood per season and appear from April-October in the south. Adult Imperial Moths do not feed. Banded Hairstreak (Satyrium calanus), which have one flight from June-August everywhere but Florida where they emerge April-May. Edward's Hairstreak (Satyrium edwardsii), has one flight from May-July in the south and June-July in the north. Gray Hairstreak (Strymon melinus), has three to four flights in the south from February-November and two flights in the north from May-September. White-M Hairstreak (Parrhasius m-album) has three broods in the north from February-October. Horace’s Duskywing (Erynnis horatius) has three broods in Texas and the deep south from January-November, and two broods in the north from April-September. Juvenal’s Duskywing (Erynnis juvenalis) has one brood from April-June, appearing as early as January in Florida. Mammals and birds eat the acorns.
Attracts
Butterflies; Moths; Pollinators; Small Mammals; Songbirds
Play value
Wildlife Food Source
Food & Medicine
Harvest time
Fall
Fruit type
Nut
Edibility
Acorns are edible if tannins are leached or boiled out.