Plant Spotlight – Rhododendrons!

Sir William Jackson Hooker, one of England’s greatest nineteenth century botanists is reputed to have said: “Perhaps with the exception of the rose, the queen of flowers, no plants have excited more interest throughout Europe than the several species of the genus Rhododendron.”

Rhododendrons are in full bloom around the country and the garden at Winterbourne is no exception. Of all the different rhododendrons at here, a couple stand out as being a bit special. Rhododendron praecox is a beautiful early flowering rhododendron which flowers in the winter. It has rosy purple flowers and can be found growing near the Tea Room entrance, often as early as February.

Rhododendron (Bow Bells Group) ‘Bow Bells’ is another favourite, flowering a bit later in late-spring. It has lovely bright pink bell-shaped flowers. This is situated in the Rhododendron Border at Winterbourne and it’s really eye catching, growing up to 1.5 metres tall.

If you’re looking for something smaller try Rhododendron yakushimanum which has pale pinkish-white flowers. It’s a lovely compact species which can be seen in the Japanese section of the Geographic Borders. It’s very slow growing eventually reaching 1 metre in height.

Rhododendron is now a favourite spring blossom in gardens world wide. However, early references to the plant reveal it has a darker history…The flower has long been seen as a symbol of danger, which is not surprising as it is extremely toxic to horses, with some animals dying within a few hours of ingesting the plant, and  honey resulting from these plants has a slightly hallucinogenic and laxative effect on humans!

Xenophon wrote of the extremely odd behaviour of Greek soldiers after having eaten honey in a village surrounded by Rhododendron ponticum during the march of the Ten Thousand in 401 BC. It appears in historic tragedy once again in 67 BC with Pompey‘s soldiers reportedly suffering many casualties following the consumption of honey made from Rhododendron deliberately left behind by Pontic forces during the Third Mithridatic War.

Despite this rather sinister side numerous varieties are celebrated as the National Flower of American States and countries around the world. One of these is Nepal, where it is known as ‘Laliguras’ and the flower is considered edible and enjoyed for its sour taste.

Rhododendrons start to appear in a more favourable light in writings of the 16th century, where it is often referred to as the Chamaerhododendron (low-growing rose tree).

They did not become popular in the United Kingdom until the late 18th Century when a fashion sprang up in the management of woodlands that included planting an under storey of exotics. These included the hardy rhododendrons of North America, which thrived in the peaty, hence acid soils.

However, the country elite loved these beautiful spring blooms so much that they wanted to enjoy them even closer to home. Thus in the last decades of the eighteenth through to the early nineteenth century many aristocratic landscaped gardens introduced a woodland garden with American plants dominated by the rhododendron, which in turn came to be known as ‘American gardens’.

Sadly, older, less hardy varieties from the continents of India and Asia often struggled with the British climate and soil. Rhododendrons like ericaceous or acidic soil which has a PH of 3.5 to 7.

Gardeners began crossing them with the hardier American varieties that grew well here and the result was that between 1820 and 1860 more than 500 different hybrid varieties were created and named in the UK.

Nowadays soil can be tested, if necessary, with a PH testing kit. If you don’t have the right soil then a peat substitute, ericaceous compost, or bracken can be added to lower the PH. If you’re still struggling to get your soil right planting compact rhododendrons, such as R. yakushimanum, in ericaceous compost in a pot is a good substitute.

The success of the hybrid varieties meant a plethora of plant to choose and the latter part of 19th century saw the gardeners of the aristocracy introduce grand planting schemes, replacing laurel in woodland as game cover and utilising the new hybrids to create great sweeping borders of colour on a grand scale. Planting included shaped borders of diamonds, triangles, and circles taking pride of place along grand driveways and bordering picturesque lakes.

The famous gardener Gertrude Jekyll, such an influence to Margaret Nettlefold in her design of the garden at Winterbourne, was a great fan of the rhododendron. In her book Wood and Garden published in 1899, she describes in detail the plan she followed for grouping them at her garden at Munstead Wood in Surrey “… I feel sure that any one with a feeling for harmonious colouring, having once seen or tried some such plan will never again approve of haphazard mixtures…The colourings seem to group themselves into six classes of easy harmonies, which I venture to describe thus:
1.  Crimsons inclining to scarlet or blood-colour grouped with claret-colour and true pink
2.  Light scarlet rose colours inclining to salmon
3.  Rose colours inclining to amaranth
4. Amaranths or magenta-crimsons
5. Crimson or amaranth-purples
6. Cool clear purples of the typical ponticum class both dark and light grouped with the lilac white…But the purples that are most effective are merely ponticum seedlings chosen when in bloom in the nursery for their depth and richness of cool purple colour.”

For your own garden Kalmia latifolia (mountain laurel) cultivars, such as ‘Elf’, look great growing alongside rhododendrons. As do Pieris japonica cultivars, such as ‘Forest Flame’. Both are evergreen shrubs in the Ericaceae family, the same family as rhododendrons.

You could also try pairing them with other shade dwelling shrubs like Viburnum x burkwoodii, a semi-evergreen shrub with balls of white flowers which have the most amazing scent. There is actually one planted in the woodland path running behind the Rhododendron Border at Winterbourne.

The plant has continued its popularity through the 20th century with the Rhododendron Society being founded in 1916. Still going strong today it is now known as the Rhododendron, Camellia and Magnolia Group, a partner group of the RHS. A registered charity since 2015, descendants of the original founders are still very much involved.

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