Rhododendrons and azaleas at the Isabella Plantation in Richmond Park
Rhododendrons and azaleas at the Isabella Plantation in Richmond Park

For once the British spring is back on its old schedule. It is extremely welcome and extremely beautiful. Wild woods of native bluebells, clusters of cowslips among grass and meadows of wild fritillaries have never been lovelier, but the beauty is not all “native” British. No native tree or big shrub can compare with our ultimate immigrants, the rhododendrons, which started to enter woods and gardens in the 1830s and have proliferated since. This weekend will see many of them at their remarkable best.

Rhododendron ponticum
Rhododendron ponticum

Why do they have so many ignorant critics? The best of rhododendrons do not have drab, overpowering leaves, nor do they sit in landscapes where they look incongruous. They cannot be blamed for the invasive habits of one member of their family, the rampageous purple-flowered ponticum. It is not their fault that they were planted in historic natural landscapes such as the great 18th-century park at Stourhead in Wiltshire where many think they look incongruous. Some very rich men have collected them, but they are not shrubs only for people who are desperate to impress. They span a wide range of colours, some of which need careful placing, but the same is true of our national favourites, roses. I have never gardened on the lime-free soil which rhododendrons need, but I certainly wish I had. The bigger ones need bigger gardens but there is still plenty of garden space in Surrey. At times I imagine myself growing older among banks of the wonderful white-flowered Rhododendron Loder’s White somewhere where the M5 motorway is a convenient, but silent, item on a road sign.

Nevermind if you, too, cannot grow them at home. Take a day off this weekend or next and go and see them at their best in a garden which is open to visitors. Londoners have the superb Isabella Plantation in Richmond Park, one of the finest examples in this country of a natural canopy of trees underplanted with beautifully chosen rhododendrons, camellias and magnolias. Do not be put off by the dazzling colours of the purple-flowered azaleas which have been planted round the main wood’s central core. They are only later additions to the inner plan. Remember that this superb wild garden was cleared and planted by the enlightened use of prison labour. In the postwar years much of the work to establish it was done by male convicts on day-release at weekends from Wormwood Scrubs and other centres of detention. Since then, what have we done with this human asset which has had any such long-term horticultural effect?

In Windsor Great Park the Savill gardens are the other obvious port of call. The great banks of rhododendrons here are wondrous, open daily to visitors, and a lasting tribute to the eye and planning of Sir Eric Savill. The gardens’ famous Punch Bowl is best known for its brilliantly coloured azaleas, but I prefer the big rhododendrons along the main gardens’ walk. They are one of the great sights of any year, so easily reached from London.

On Sunday I will be enjoying a special heaven, the historic wood of rhododendrons adjoining the park at Bowood House, near Calne, Wiltshire. It is so easily accessible off the M4 motorway, but until a few years ago I never realised the exceptional beauty which is open here to the public. Since the 1840s fine rhododendrons have been planted by the Lansdowne family beneath their woodland’s canopy of superb oak trees. Admittedly, I see them after lunch in the company of far greater rhododendron experts than myself but I am not swayed by the effects of a glass or three of wine. Cold sober, any visitor would be stunned by the sight of lavender-blue Rhododendron augustinii and superb white rhododendrons bearing the Loder name among a natural carpet of English bluebells. Rhododendrons often suffer by being planted among heavy dark green conifers. At Bowood there is nothing heavy about them at all, though they have become tall banks of flower. Mown rides of natural grass are beautifully maintained throughout the wood and carefully chosen planting is still extending it. On a fine afternoon it is bliss.

In Hampshire, of course, there is Exbury Garden near Beaulieu, just off Junction 2 of the M27, for those of you who yearly write in for advice on how to locate it. Since the 1920s it has been a fabulous Rothschild collection and now extends to more than 200 acres. It comes complete with a steam railway and garden-buggies for those who do not feel able to walk too far. The famous Exbury hybrid azaleas are bred here and are shown in stunning colours, but there are also superb big rhododendrons, including lovely members of the Hawk group. Gardeners find plenty to buy and note on a visit and the garden’s contribution to the breeding and study of rhododendrons is admirable.

In Derbyshire I recently hit on an unexpected rhodo-haven. Near Matlock, Lea Gardens extend for four acres down a sloping wooded hillside, which is coniferous in places but thoughtfully planted and landscaped. It has been a long-running family enterprise and sells excellent locally grown plants of varieties on view in the gardens themselves. It is open daily from 10am to 5.30pm and offers excellent home-made teas to its many devotees. Some of the red-flowered varieties are especially enviable and I am grateful to the local FT readers who first urged me to go and see them.

On acid soil most rhododendrons are refreshingly easy to grow. Their roots tend to run near the surface of the soil and so they benefit from a thick layer, or mulch, of lime-free leaf-mould or waste material to keep them from drying out. It helps if they are deadheaded after flowering to stop them wasting energy on setting seeds, but when they become big in a big garden the job is obviously too much. The crucial point, of course, is that all soil and water and mulching must be free of lime, which turns them a fatal yellow. Admirers struggle to grow a token rhododendron or two in limy areas by dosing them regularly with the counteracting chemical, Sequestrene. The results are never very impressive and somehow they look incongruous among a surrounding lime-loving flora.

Big displays of rhododendrons have vanished nowadays from the Chelsea Flower Show and we will not see them in a fortnight’s time. Even the designers of outdoor gardens make less use of them although rhododendrons are easy to move, even in May, when big plants. The famous old rhodo-nursery of Waterers has been absorbed by Notcutts whose basic list is still a good place to begin a small collection of members of the family. Specialists still exist, traceable through the RHS Plantfinder, including the good range from Loder Plants in West Sussex, bearing a great rhodo name (at www.rhododendrons.com, no less). I will not be spending my rhododendron lunch in a happy post-vinous haze. I always ask the top experts which is the variety we amateur gardeners ought to choose. Consistently they answer Rhododendron May Day, so the afternoon, I assure you, is well spent.

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