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Rhododendron japonicum - (Blume.)Schneid.

Common Name Japanese azalea
Family Ericaceae
USDA hardiness 4-8
Known Hazards Although no specific mention of toxicity has been seen for this species, it belongs to a genus where many members have poisonous leaves. The pollen of many if not all species of rhododendrons is also probably toxic, being said to cause intoxication when eaten in large quantities[183].
Habitats Dense woods in mountains in C. and S. Japan, to 1800 metres[11, 58].
Range E. Asia - Japan.
Edibility Rating    (1 of 5)
Other Uses    (0 of 5)
Weed Potential No
Medicinal Rating    (1 of 5)
Care (info)
Fully Hardy Moist Soil Semi-shade Full sun
Rhododendron japonicum Japanese azalea


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Rhododendron japonicum Japanese azalea
http://commons.wikimedia.org/wiki/User:KENPEI

 

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Summary


Physical Characteristics

 icon of manicon of shrub
Rhododendron japonicum is a deciduous Shrub growing to 2 m (6ft 7in).
See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from April to May. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects.
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid soils and can grow in very acid soils.
It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

UK Hardiness Map US Hardiness Map

Synonyms

R. metternichii. Sieb.&Zucc.

Plant Habitats

Woodland Garden Dappled Shade; Shady Edge;

Edible Uses

Edible Parts: Leaves
Edible Uses:

Leaves[177]. No more details are given but some caution is advised, see the notes above on toxicity.

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Diuretic  Tonic

Diuretic, tonic[174].

References   More on Medicinal Uses

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Other Uses

None known

Special Uses

References   More on Other Uses

Cultivation details

Succeeds in a most humus-rich lime-free soils except those of a dry arid nature or those that are heavy or clayey[1]. Prefers a peaty or well-drained sandy loam[1]. Succeeds in sun or shade, the warmer the climate the more shade a plant requires[200]. A pH between 4.5 and 5.5 is ideal[1]. This species is closely related to R. molle and perhaps not distinct from it[200]. Succeeds in a woodland though, because of its surface-rooting habit[200], it does not compete well with surface-rooting trees[1]. Plants need to be kept well weeded, they dislike other plants growing over or into their root system, in particular they grow badly with ground cover plants, herbaceous plants and heathers[200]. Plants form a root ball and are very tolerant of being transplanted, even when quite large, so long as the root ball is kept intact[200]. Plants in this genus are notably susceptible to honey fungus[200].

References   Carbon Farming Information and Carbon Sequestration Information

Temperature Converter

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Plant Propagation

Seed - best sown in a greenhouse as soon as it is ripe in the autumn and given artificial light. Alternatively sow the seed in a lightly shaded part of the warm greenhouse in late winter or in a cold greenhouse in April. Surface-sow the seed and do not allow the compost to become dry[200]. Pot up the seedlings when they are large enough to handle and grow on in a greenhouse for at least the first winter. Layering in late July. Takes 15 - 24 months[78]. Cuttings of half-ripe wood, August in a frame. Difficult[78].

Other Names

If available other names are mentioned here

Native Range

TEMPERATE ASIA: Japan (Honshu, Kyushu, Shikoku)

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Rhododendron anthopogon Shrub0.6 6-9  LMSNM121
Rhododendron arboreum Shrub12.0 6-9  LMSNM123
Rhododendron aureumRosebayShrub0.5 -  LMSNM02 
Rhododendron campanulatum Shrub4.5 4-8  LMSNM012
Rhododendron ferrugineumAlpenroseShrub1.5 4-8  LMSNM013
Rhododendron griersonianum Shrub3.0 7-10  LMHSNM003
Rhododendron indicumRhododendronShrub2.0 5-9  LMSM103
Rhododendron kaempferi Shrub2.5 4-8  LMSM103
Rhododendron lapponicumLapland RosebayShrub1.0 -  LMSNM10 
Rhododendron lutescens Shrub3.0 6-9  LMSNM002
Rhododendron luteumHoneysuckle AzaleaShrub2.5 4-8  LMSM002
Rhododendron maximumRosebay Rhododendron, Great laurelShrub3.5 3-7  LMSM012
Rhododendron molleChinese AzaleaShrub2.5 6-9  LMSM011
Rhododendron mucronulatum Shrub2.5 4-8  LMSNM10 
Rhododendron periclymenoidesPink azalea, Pinxter flowerShrub2.0 4-8 MLMHFSNDM102
Rhododendron 'PJM' Shrub3.0 -  LMSNM00 
Rhododendron ponticumRhododendronShrub5.0 6-9  LMSM012
Rhododendron x praecox Shrub1.5 5-9  LMSNM003

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

Expert comment

Author

(Blume.)Schneid.

Botanical References

1158200

Links / References

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