Valley oak

Sun

Full sun; young trees tolerate light shade.

Water

Water young trees deeply during dry weather. Established trees usually need little summer irrigation where roots can reach deep moisture; avoid frequent watering around the trunk.

Soil

Deep loam or clay with access to subsoil moisture; tolerates alkaline soil and seasonal flooding, but not permanently waterlogged ground.

Height

60-100 ft (18-30 m)

Spread

50-80 ft (15-24 m)

Flowers

Spring: yellow-green male catkins and tiny, inconspicuous female flowers.

Foliage

Rounded, deeply lobed green leaves with softly hairy undersides; autumn colour is usually yellow to brown.

Growth

Moderate to fast when young with adequate moisture; slower on dry or restricted sites.

Care needed

Medium

• Drought tolerant
• Heat tolerant
• Wildlife

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   9 ft (2.9 m)

2. After 1 year

   13 ft (3.9 m)

3. After 2 years

   16 ft (5 m)

4. After 3 years

   20 ft (6 m)

5. After 5 years

   27 ft (8.2 m)

About 20 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the US

Growth rate

Moderate

• Choose a permanent site well away from buildings, overhead wires and paving; allow for the full mature crown.
• Water deeply through the first few dry seasons, letting the surface soil dry between soakings.
• Spread organic mulch over the root area, keeping it clear of the trunk.
• Avoid lawn irrigation, soil compaction, digging and changes in soil level beneath established trees.
• Do not fertilise routinely; feed only if a soil test or diagnosed deficiency indicates a need.
• Stake only if the young tree cannot stand securely, and remove supports once it is anchored.

Pruning. Train young trees during the dormant season, retaining a strong central framework and removing competing leaders while cuts are small. Have a qualified arborist assess mature limbs; avoid topping and unnecessary large cuts.

Autumn

Plant after reliable rain begins, while the soil is still workable.

Late autumn

Collect freshly fallen, sound acorns for immediate sowing in deep containers protected from rodents.

Winter

Check the branch structure and carry out light formative pruning on young trees.

Spring

Refresh mulch and check that tree ties are not rubbing or constricting the trunk.

Summer

Deep-water young trees during prolonged dry spells; keep irrigation away from the trunk.

Late summer

Inspect for dead branches, cracks or fungal growth and arrange an arborist assessment if needed.

• Use as a single specimen in a large garden or park, with space to appreciate its spreading crown.
• Anchor a California native meadow, keeping planting and soil disturbance light beneath the canopy.
• Create broad summer shade over an informal seating area, with regular professional inspection of mature branches.
• Restore oak savanna character on large properties with widely spaced trees and native grasses.

Garden styles it suits: California native, Grand estate, Native meadow, Wildlife garden, Mediterranean and Rewilded.

Plant it with: Deer grass, Purple needle grass, California fescue, California poppy and Western redbud.

Wildlife: Acorns feed jays, woodpeckers, squirrels and other mammals. The foliage supports many insects, including moth and butterfly larvae, while large old trees provide nesting sites and cavities.

• Root and crown rot: frequent summer irrigation and wet soil around the trunk encourage decay; keep the root collar dry and seek an arborist's advice if the canopy declines.
• Oak galls: unusual swellings on leaves or twigs are usually harmless; avoid routine insecticide treatment.
• Leaf-eating caterpillars: established trees usually recover from occasional defoliation; identify the insect before considering treatment.
• Large-limb failure: mature trees can shed heavy branches, sometimes without obvious warning; arrange professional inspections and avoid placing vulnerable structures beneath major limbs.

Acorns, buds and leaves contain tannins and can poison dogs, cats and horses if eaten in quantity; horses are particularly vulnerable to serious digestive and kidney damage. Raw acorns are not suitable for people to eat without proper processing to remove tannins. Seek veterinary advice promptly after substantial ingestion.

• Blue oak (Quercus douglasii)

  Usually a smaller tree with blue-grey leaves and shallower, less pronounced lobes; valley oak has greener, more deeply lobed leaves.

• Oregon white oak (Quercus garryana)

  Its leaves generally have broader, more regularly arranged lobes; valley oak often has deeper, narrower sinuses. Leaf shape overlaps, so use acorns and local range as additional clues.

• English oak (Quercus robur)

  English oak has very short leaf stalks, small ear-like lobes at the leaf base and acorns on long stalks; valley oak has longer leaf stalks and acorns that are nearly stalkless.

The species name lobata refers to its lobed leaves, while valley oak describes its characteristic habitat in California's valleys.

Propagation. Grow from fresh acorns collected in autumn; do not let them dry out. Sow promptly in deep containers or in their final position, protect from rodents, and plant container-grown seedlings while young to avoid restricting the developing taproot.

Accepted botanical name

Quercus lobata

In the US and Canada

Native in the lower 48 states.

Native range

Alabama, Arkansas, Delaware, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Mississippi and Missouri.

Measured

Soil pH 4.5 to 7.5. Average height 1845 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.