Dwarf Rhododendron trichostomum 'Collingwood Ingram'  AGM

Dwarf Rhododendron trichostomum 'Collingwood Ingram' AGM


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Flowering Month:
Flower Colour:
Light Pink
Height After 10 Years:
To -15 °C
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3 litre
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5 litre
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(POGONANTHUM  H5)  Very pretty pale pink daphne like flowers in striking trusses during May - June. This is a most beautiful low growing shrub with aromatic grey-green oblong lanceolate leaves. This is one of the best clones available and it is rare in cultivation. Height 25 - 50cm in 10 years.

This selection received the RHS FCC when exhibited by Lady Anne Berry in 1976, from her garden at Rosemoor. It is pinker than most trichostomums, and was named for her friend Collingwood 'Cherry' Ingram who inspired her to develop her garden at Rosemoor, which she later gifted to the RHS.

As a word of warning, we have found that deer and rabbits find this plant particularly tasty.

Dwarf Rhododendrons don't mind the sun but they hate too much heat, so do avoid reflected heat from South facing walls and patios. It dislikes fertilizer, needs cool roots in the summer and good drainage. It will tolerate near neutral soil.

Epithet: Hairy-mouthed (!) 

  • Recommended for fabulous flowers.
  • Plantsman range.
  • Ideal position: needs careful site selection, see above
  • Habit: compact.
  • Group: Dwarf Rhododendron.
  • Subsection: Pogonanthum.
  • Species introduction date: pre 1950 (1908).
  • Species distribution: trichostomum distribution - Yunnan, Sichuan. Forest, scrub and open slopes, often surprisingly dry.
  • Approximate altitude: 2.500-4,300m
  • Ideal soil: pH 4.5 to 6.5
  • RHS Hardiness Rating: H5
  • How we usually propagate this plant: Cutting.
  • Awards: RHS First Class Certificate, and Award of Garden Merit.


Customer Reviews

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"Good quality plant supplied"
Star Rating 5
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"A belated response to tell you how delighted I am to have received those two dwarf rhododendrons, trichostomum and campyloginum, having searched in vain for years a nursery that stocked them - and both so sturdy and healthy, thank you."
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"Five stars for a plant of decent size, well-budded with nice dense foliage - and the same for R. cephalanthum ssp. crebreflorum which was part of the same order. Quick delivery time too. Can't ask for better than that !"
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Good to know

Tough alpine rhododendrons for the front of borders, or in containers, which mainly flower in April.

Most of these dwarf rhododendrons originate from alpine regions, and from the Himalayas at altitudes of 3000-5000 metres. They grow on scree, rocky ground and open mountains where although exposed, they have good drainage. Often they are covered with snow during the winter's which insulates them from the worst of the weather. They range from tiny gems such as Rhododendron keiskei 'Yaku Fairy', to larger growers up to heights of around 80 cm after 10 years. Being alpine plants, they prefer moist, cooler climates, and generally favour the cooler conditions of Northern England and Scotland. They will struggle on a hot sunny patio, and prefer a cooler spot out of direct sunlight. Dwarf rhododendrons are suitable for growing in pots and containers; re-pot every 3 years for best performance.

Flowers can vary from long tubular bells, to bell-shaped, and also flat faced. Leaves are generally small 10-20mm long, though the red R. repens hybrids can have leaves up to 50mm long. Most varieties will bud up and flower as a 3 litre plant.

If space permits, they look great planted in groups of three, and will merge to form a larger clump. Recommended plant spacing is 3 plants per square metre. They also grow well in pots, but keep them out of direct sunlight so that they stay cooler in summer. Dwarf rhododendrons like moist acidic soil, with good drainage, and plenty of organic matter such as leaf-mould and added ericaceous compost. Plant no deeper than the top of the rootball, and dig in plenty of good ericaceous compost around the sides. Dwarf rhododendrons may need protection from deer and rabbits. Pruning is not normally required, but wayward shoots can be cut back straight after flowering to improve shape. 

Please note: Dwarf rhododendrons scorch easily with too much fertilizer. Give species no feed, and hybrids half a teaspoon of slow-release feed at the 3 litre size, rising to a tablespoon full for mature plants.

For further advice, For further advice, see here

Size Guide

Size guide

The Basics

Ideal soil

Acidic soil, good organic content, pH 4.5-6.0. Inkarho range of rhododendrons will tolerate soils up to pH7.5

Sun or Shade

Light dappled shade is best for most varieties.


Refer to hardiness rating. Give young plants protection.

Site Selection

Avoid close to trees, roots, invasive weeds, walls, hot patios, dry banks and waterlogged soils. Do not use weed matting or stone mulch.

Plant spacing

Use the height shown in 10 years as a guide to the distance between each plant. Allow room for plant to fill out. If planting closer for instant impact, be prepared to move plants after a few years.


  • 3 litre pot, dig in 10-20 litres of ericaceous compost.
  • 7.5 litre pot, dig in 20-30 litres of ericaceous compost.
  • 70-80cm specimen, dig in 60 litres of ericaceous compost.
  • 100-120cm specimen, dig in 120 litres of ericaceous compost.

Planting depth

Plant high in the ground, with the top of the rootball visible.


Slow-release ericaceous feed recommended in March and straight after flowering.


Recommended every few years.


The key ingredient! Keep moist all season, especially the critical time at end of June for flower bud initiation. Tap water is better than no water. Heavy dose at least once per week in dry weather.


Ensure good drainage in winter, especially with yellow flowering varieties. Avoid waterlogged sites.


Rhododendrons and Camellias: Not normally required. Tidy wayward shoots after flowering.

Evergreen azaleas and Bloombux can be clipped into a low hedge.

Magnolias and Acers: Formative pruning when young to shape into a tree or bush.


Remove old flower-heads, particularly on young or weak plants.

For further advice see here

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