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Summary

Physical Characteristics

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 itâ€™s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants

Latin Name	Common Name	Habit	Height	Hardiness	Growth	Soil	Shade	Moisture	Edible	Medicinal	Other
Rhododendron anthopogon		Shrub	0.6	6-9		LM	SN	M	1	2	1
Rhododendron arboreum		Shrub	12.0	6-9		LM	SN	M	1	2	3
Rhododendron aureum	Rosebay	Shrub	0.5	-		LM	SN	M	0	2
Rhododendron campanulatum		Shrub	4.5	4-8		LM	SN	M	0	1	2
Rhododendron ferrugineum	Alpenrose	Shrub	1.5	4-8		LM	SN	M	0	1	3
Rhododendron griersonianum		Shrub	3.0	7-10		LMH	SN	M	0	0	3
Rhododendron indicum	Rhododendron	Shrub	2.0	5-9		LM	S	M	1	0	3
Rhododendron kaempferi		Shrub	2.5	4-8		LM	S	M	1	0	3
Rhododendron lapponicum	Lapland Rosebay	Shrub	1.0	-		LM	SN	M	1	0
Rhododendron lutescens		Shrub	3.0	6-9		LM	SN	M	0	0	2
Rhododendron luteum	Honeysuckle Azalea	Shrub	2.5	4-8		LM	S	M	0	0	2
Rhododendron maximum	Rosebay Rhododendron, Great laurel	Shrub	3.5	3-7		LM	S	M	0	1	2
Rhododendron molle	Chinese Azalea	Shrub	2.5	6-9		LM	S	M	0	1	1
Rhododendron mucronulatum		Shrub	2.5	4-8		LM	SN	M	1	0
Rhododendron periclymenoides	Pink azalea, Pinxter flower	Shrub	2.0	4-8	M	LMH	FSN	DM	1	0	2
Rhododendron 'PJM'		Shrub	3.0	-		LM	SN	M	0	0
Rhododendron ponticum	Rhododendron	Shrub	5.0	6-9		LM	S	M	0	1	2
Rhododendron x praecox		Shrub	1.5	5-9		LM	SN	M	0	0	3

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.

Rhododendron japonicum - (Blume.)Schneid.