Coast Live Oak (Quercus agrifolia)

Coast Live Oak

Quercus agrifolia

Dense evergreen canopy shelters coastal hills, a quiet sentinel of California’s shoreline. Evergreen broadleaf tree; common name: California live oak.

Full sun
1–2/week
Moderate
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Plant Needs

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Sunlight Full sun to partial shade; tolerates coastal fog and windy conditions without significant damage
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Watering Established mature trees are highly drought-tolerant; water young trees deeply every 1-2 weeks during dry spells
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Temperature Tolerates mild frost and coastal heat; avoid prolonged exposure to temperatures below -5°C
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Characteristics

  • Leaf: Thick, leathery, oblong leaves with spiny margins; glossy dark green upper surface, pale gray-green underside
  • Flower: Male catkins are yellow-green, pendulous; female flowers are small, reddish, axillary
  • Stem/Bark: Mature bark is thick, furrowed, dark brown to gray; young stems are smooth and green
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Horticulturist's Insider Field Notes (No AI Fluff)

The Golden 'Finger Test' Rule

Never water on a strict calendar. Stick your index finger 2 inches into the soil. If it feels cool and damp, wait 2–3 days. If bone dry, water thoroughly until it drains from the bottom holes.

Empty the Saucer After 20 Minutes

The #1 houseplant killer is water sitting in the catch tray. Stagnant runoff water starves roots of oxygen and causes root rot.

Turn the Pot Every 2 Weeks

Houseplants naturally lean toward the nearest window light. Give the pot a quarter-turn biweekly to maintain balanced, symmetrical architecture.

Wipe the Dust Away

Dust on leaves acts like a heavy sunshade. Gently wipe broad foliage with a damp cloth monthly to maximize photosynthesis and air purification.

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Care Guide

Watering

Water young trees deeply every 1-2 weeks; established trees need no supplemental water in most years

Fertilization

Apply slow-release balanced fertilizer once in early spring. Fertilize only young, newly planted trees to support establishment

Composted eggshell powder:Sprinkle a thin layer around the tree’s drip line in early spring; avoid direct contact with the trunk to prevent bark burn
Pruning
  • Remove dead, diseased, or crossing branches in late winter to early spring to maintain canopy health
  • Thin dense inner branches to improve airflow and light penetration
  • Avoid heavy pruning; retain the tree’s natural spreading, rounded form
  • Trim suckers growing from the base to redirect energy to the main canopy
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Pet & Human Toxicity & Emergency Guide

⚠️ Toxic to Pets (Cats & Dogs)

Toxicity Warning: Veterinary toxicology registers Coast Live Oak (Quercus agrifolia) as possessing biochemical compounds (such as insoluble oxalates, alkaloids, or saponins) that pose ingestion hazards to felines and canines.

Feline Ingestion Risks (Cats)

Oral pain, hypersalivation (excessive drooling), pawing at mouth, swelling of tongue or lips, vocalization, and vomiting.

Canine Ingestion Risks (Dogs)

Oral mucosal irritation, gagging, retching, lack of appetite, lethargy, diarrhea, and difficulty swallowing.

Immediate Emergency First-Aid

Do NOT induce vomiting without veterinary instructions! Carefully remove remaining plant pieces, gently rinse mouth with cool water, and monitor breathing.

🚨 Pet Ingestion Emergency? Instant Plant & Toxicity Scan

Chewed leaf or stem? Open PlantFun App to scan the plant, immediately verify the botanical species, and view ASPCA toxicity severity ratings & vet first-aid advice.

Emergency Plant Scan
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Troubleshooting & Common Plant Problems

Quick diagnostic guide for common care issues affecting Coast Live Oak (Quercus agrifolia):

Yellowing Leaves

Most commonly caused by overwatering or poor drainage. Ensure topsoil dries out between waterings and check for root ventilation.

Brown or Crispy Leaf Tips

Low ambient humidity, hard tap water minerals, or direct midday sunburn. Increase humidity and use filtered water.

Drooping or Wilting Foliage

Indicates dehydration or root damage from prolonged waterlogging. Inspect soil moisture and root firmness.

Common Pests (Spider Mites, Aphids)

Dry indoor air encourages pests. Wipe leaves with a damp cloth and treat with insecticidal soap or neem oil.

🌿 Instant AI Plant Health Check

Take a photo of any leaf on PlantFun App to get instant diagnosis of diseases, pests, and custom care recovery steps.

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Propagation & Repotting Guide

  • Taking Cuttings: During active spring or summer growth, take a healthy 4–6 inch cutting just below a node using clean shears.
  • Rooting Medium: Place cuttings in fresh water or moist perlite mix in bright, indirect light; refresh water weekly.
  • Potting Up: Transplant into well-draining potting mix once roots reach 2 inches in length (typically 3–5 weeks).
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Seasonal Care Calendar

  • Spring & Summer (Active Growth): Water thoroughly as topsoil dries; apply diluted balanced fertilizer monthly; encourage steady growth.
  • Autumn (Transition): Gradually reduce watering frequency as daylight hours shorten; discontinue fertilization.
  • Winter (Dormancy): Water sparingly only when soil is mostly dry; protect from cold window drafts; keep in warm room.
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Frequently Asked Questions

How often should I water my Coast Live Oak?

Water thoroughly when the top 1–2 inches of soil feel dry. In active growth (spring/summer), water every 1–2 weeks; reduce significantly in winter.

Where is the best indoor location for Coast Live Oak?

Position in bright, filtered indirect light (e.g., near an east or south-facing window with sheer curtains). Avoid harsh direct midday sun.

Is Coast Live Oak toxic to pets?

ASPCA: Toxic; gallotannins may cause gastrointestinal irritation and potential kidney damage in severe cases

When should I repot my Coast Live Oak?

Repot every 1–2 years in spring when roots outgrow the drainage holes or the soil depletes nutrients.

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Garden Uses & Culture

Culture: Symbolizes strength and longevity in California coastal ecosystems; valued in native landscaping for wildlife support

Usage: Ornamental shade tree; provides habitat and food for birds, mammals, and pollinators

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