Rhododendron
Rhododendron ponticum

Family: Ericaceae

What it is like

Rhododendron ponticum is an evergreen Shrub growing to 5 m (16ft 5in). See above for USDA hardiness. It is hardy to UK zone 7. It is in leaf all year, in flower from May to June. 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). It prefers moist soil.

Height (m): 5

Where it is found

Rich forests under Fagus, Picea and Abies species, it is also found above the tree line. Sandy and peaty soils in woods and open places in Britain.

W. Europe to the Caucasus and Lebanon. Naturalized in Britain.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 0

Medicine

Rating: 1

A medicine made from the plant is used to treat heart and circulation malfunctions, but it should not be used without expert supervision.

Antirheumatic: Treats rheumatism.

Cardiac: Used in the treatment of heart problems.

Other

Rating:

Plants are being grown as a hedge at the RHS gardens in Wisley, Surrey. It tolerates quite hard clipping.

Hedge: Plants that can be grown as hedges.

Hedge: Hedge

How it is grown

Succeeds in a most humus-rich lime-free soils except those of a dry arid nature or those that are heavy or clayey. Prefers a peaty or well-drained sandy loam. A pH between 4.5 and 5.5 is ideal. Succeeds in sun or shade, the warmer the climate the more shade a plant requires. Hardy to about -15°c. Plants are self-sowing aggressively in British woodlands and are often out-competing native trees by filling the understorey and preventing natural regeneration. They are considered to be a pernicious weed by many environmentalists. Succeeds in a woodland though, because of its surface-rooting habit, it does not compete well with surface-rooting trees. 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. 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. Plants in this genus are notably susceptible to honey fungus.

Propagating it: 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. 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. Cuttings of half-ripe wood, August in a frame. Difficult.

Best place to grow: Woodland Garden Dappled Shade; Shady Edge; Hedge;

Habit: Shrub

Hardiness: 6-9

Growth:

Soil: Light (sandy), medium

Shade: Semi-shade

Moisture: Moist

Things to keep in mind

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.

Its other names

Local names

Synonyms

R. lancifolium. R. speciosum.