California Black Oak Quercus kelloggii
California Black Oak is a perennial tree native to the lower 48 states. It grows to 85 ft and blooms May in part shade – shade, with brown fruit. A keystone plant for native insects and the food web.
Growing & care
USDA PLANTS · TRY- Sun
- Part shade – shade
- Soil & moisture
- Medium moisture
- Soil pH
- 5.5–7.5
- Fertility need
- Low
- Adapts to
- Coarse (sandy), Medium (loam)
- Hardiness
- USDA zone 7+
- Drought tolerance
- High
- Shade tolerance
- Low
- Wet-soil tolerance
- Low waterlogging
- Height
- 85 ft
- Mature width
- ~ 51 ft wide DERIVED derived estimate — open-grown crown allometry (height × growth-form ratio); not a measurement
- Spacing
- 7–12 ft apart from USDA planting density
- Spread
- None — clumping
- Growth rate
- Slow
- Growth form
- Single stem
- Lifespan
- Perennial · long-lived
- Foliage
- Deciduous broadleaf · medium texture
- Active growth
- Spring & summer
- Fruit
- Brown
- Propagate by
- Seed, Bare root, Container
- Seed starting
- Needs cold stratification a cold-moist spell before it germinates
- Seeds ripen
- Autumn – Summer seed-collection / harvest window
- In the trade
- Contract growing only
- Deer browsing
- Medium moderately palatable
- Resprouts if cut
- Yes regrows after top-kill
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~532 caterpillar species · keystone genus
Quercus supports ~532 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a powerhouse genus.
Recorded feeding on Quercus in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees 1 bee visitor
1 native & managed bee species is documented visiting California Black Oak :
Wildlife & visitors 1 bird · 1 nectaring
Open records of who else uses California Black Oak — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 1 bird species (fruit, seed, browse):
1 adult butterfly & moth species is recorded nectaring at its flowers:
Related plants
More Quercus →
How we know this (4) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
For woody plants that have a height but no measured crown, we estimate width = height × a crown-to-height ratio fit for that plant’s form (conifers narrower than broadleaf trees, shrubs widest), calibrated on our measured open-grown crowns and capped at the largest one ever measured. A measured crown always wins; herbaceous plants get nothing (no anchor).
Honest limits: A coarse class-median estimate for garden-scale spacing, not a measurement; woody single/multi-stem forms only.
Sources for this entry (36) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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