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Augustine's Rhododendron (Rhododendron augustinii), whole plant
  • Augustine's Rhododendron — close-up of leaves and flowers
  • Augustine's Rhododendron — seasonal appearance
  • Augustine's Rhododendron in a garden setting

Augustine's Rhododendron

Rhododendron augustinii

Hard · Experienced growers

About Augustine's Rhododendron

Rhododendron augustinii is one of the rare rhododendrons that can approach true blue, with lavender-blue to violet funnel-shaped flowers in mid-spring. Native to central and western China, especially Hubei, Sichuan, and Guizhou, it grows as an evergreen shrub about 1.5-4 meters tall. Augustine Henry introduced it to Western horticulture from Hubei in 1885, and E. H. Wilson later collected it for major nurseries and arboreta. It became a key parent in the blue rhododendron breeding line, giving rise to classic descendants such as 'Blue Diamond' and 'Electra'. Best in cool maritime climates with acidic, humus-rich soil and dappled shade, it is difficult in hot continental summers.

  • Shade-tolerant
  • Evergreen
WATER
Wants wet
Keep moist
LIGHT
Part shade
2–4 hrs direct
HARDY
Hardy to 0°F (-18°C)
USDA hardiness zones 7–9

How to care for Augustine's Rhododendron

Watering

  • Springevery 5 days
  • Summerevery 3 days
  • Fallevery 7 days
  • Winterevery 14 days

Soil · Acidic · pH 4.5–6

  • Top dressingPine needle mulch10%
  • Main mixAcid-lover mix + peat 3:175%
  • DrainageGravel15%

Never add lime or wood ash — it cancels out the acidity.

FERTILIZER

Acid-Loving Feed 4-3-4

One bag does both jobs. An acid feed carries the usual nitrogen, phosphorus and potassium, plus the sulfur and iron that keep the soil sour enough for the roots to take them up at all.

N36%P27%K36%
  • Nitrogen · Leaves
  • Phosphorus · Roots + Blooms
  • Potassium · Strength
  • Springevery 30 days
  • Summerevery 45 days
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At a Glance

  • NativeEast Asia
  • Height6–12 ft (1.8–3.7 m)
  • Spread5–10 ft (1.5–3 m)
  • Flower colorBlue, Purple
  • Foliage colorGreen
  • Fruit colorBrown
  • SoilLoamy, Moisture-retentive, Acidic
  • LocationsYard

Bloom time

BLOOM CYCLE

Peak bloom

Apr

J
F
M
A
M
J
J
A
S
O
N
D

Lavender-blue to violet flowers in mid-spring; breeding parent of blue rhododendron hybrids.

Fragrance

LIGHT FRAGRANCE

The flowers have a very light sweet scent.

Toxicity

Humans Toxic · Pets Toxic

grayanotoxins

Toxic

  • Leaf
  • Flower
  • Nectar
  • Ingestion

EXPOSURE Eating leaves, flowers, and nectar.

EFFECT Grayanotoxins cause vomiting, low blood pressure, cardiac arrhythmia. 'Mad honey' from Rhododendron nectar known since antiquity.

NOTE Documented concern for humans: Grayanotoxins cause vomiting, low blood pressure, cardiac arrhythmia. 'Mad honey' from Rhododendron nectar known since antiquity.

Toxic

  • All
  • Ingestion

EXPOSURE Eating any part of the plant.

EFFECT Severe GI, cardiac, neurological toxicity.

NOTE ASPCA lists all Rhododendron as toxic to dogs, cats, and humans. Can be fatal.

Toxic

  • All
  • Ingestion

EXPOSURE Eating any part of the plant.

EFFECT Severe GI, cardiac, neurological toxicity.

NOTE ASPCA lists all Rhododendron as toxic to dogs, cats, and humans. Can be fatal.

Educational information, not medical or veterinary advice. If exposure is suspected, contact a doctor or veterinarian.

DISTRIBUTION

Augustine's Rhododendron · Native
  • Native
  • East Asia

History

Illustrated historical scene for Augustine's Rhododendron

Rhododendron augustinii is native to central and western China — Hubei, Sichuan, Guizhou, Yunnan — at elevations of 1500-3300 m. It was collected by Irish-born plant hunter Augustine Henry during his 1880s Chinese expeditions for the Imperial Chinese Maritime Customs Service at Yichang. Henry's plant collections (over 150,000 specimens) revolutionized Western understanding of Chinese flora.

E.H. Wilson re-collected R. augustinii for the Veitch Nursery in 1900 and for the Arnold Arboretum in 1908, establishing it in Western cultivation. The lavender-blue flowers — genuinely blue, not the lilac or purple that usually passes for 'blue' in rhododendrons — made it the holy grail of 20th-century rhododendron breeders. It served as the primary parent for the 'Blue' series of hybrids: 'Blue Diamond' (Crosfield, 1934), 'Blue Tit' (Crosfield), 'Electra' (Rothschild, 1937), 'Blue Star,' and numerous Pacific Northwest and British cultivars.

Performs best in cool maritime climates with acid humus soil, dappled shade, and wind protection. Difficult or impossible in hot continental climates like the US Southeast or Midwest. Hardy to USDA zone 7. Collected by Augustine Henry in Hubei in 1885 — named for him. Became the primary parent of 'blue' rhododendron hybrids in 20th-century breeding.

Symbolism & meaning

What It Symbolizes

Augustine's Rhododendron makes visible rare beauty — true-blue rhododendron flowers are extraordinarily uncommon, and its lavender-blue blooms feel almost mythical in spring. It also carries the romance of plant hunting, named for Augustine Henry, whose late-19th-century Chinese explorations introduced this and many other treasures to Western gardens. A rhododendron whose color story is also a chapter of botanical history.

  • Rare Beauty — True-blue rhododendron flowers are extraordinarily uncommon
  • Plant Hunting — Carries the legacy of Augustine Henry's Chinese exploration

Where the Name Comes From

Rhododendron from Greek 'rhodon' (rose) + 'dendron' (tree); 'augustinii' honors Augustine Henry, Irish plant hunter.

Uses & Fun Facts

  • Lavender-blue rhododendron as woodland-edge spring focal shrub
  • One of the truest blue rhododendrons for shaded gardens
  • Funnel flowers visited by bumblebees in early spring

Related plants

More Rhododendron plants

Plants with similar care

Frequently asked questions

How often should I water Augustine's Rhododendron?

In summer, water about every 3 days; in winter, about every 14 days. Adjust for heat, pot size and drainage.

How much light does Augustine's Rhododendron need?

Part shade: 2–4 hrs direct. Watch the leaves — scorching or stretching means the light needs adjusting.

Is Augustine's Rhododendron toxic to cats or dogs?

Pets Toxic (Dogs Toxic · Cats Toxic) Educational information, not medical or veterinary advice. If exposure is suspected, contact a doctor or veterinarian.

Is Augustine's Rhododendron easy to grow?

It is considered challenging and rewards experienced growers.

When does Augustine's Rhododendron bloom?

It typically blooms Apr in the Northern Hemisphere.

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