British-American alliance was forged centuries earlier, says MONTY DON

My childhood was dominated by the Second World War. I was born ten years after it finished but every adult I knew had lived or fought through it, and every story book, comic and film seemed to be based upon it. 

The image of plucky, isolated Britain standing alone against the full might of the Nazis dominated every portrayal. 

The enduring popularity of Dad’s Army shows that this version of events still has deep resonance. 

But the more complicated truth is that without American help we would almost certainly have succumbed and definitely would not have been able to invade and regain Europe.

Monty with his camassias. The gardening expert says American and British gardens are bonded together

As the 75th anniversary of D-Day arrives on Thursday, it is right and proper to see it as above all a celebration of Britain and the United States working together in harmony towards a common goal.

All this might seem a long way from gardens and plants, but in fact American and British gardens have been bonded together by mutual plants, skills and experience ever since the first settlers founded Jamestown, Virginia, in 1607.

I am currently filming a series for the BBC on American gardens, to be shown at the beginning of next year. 

A VERY BRITISH LUPIN

The herbaceous lupin, Lupinus polyphyllus, was brought to Britain from the American west coast in the 1820s by the great botanist David Douglas, after whom the Douglas fir was named.

Russell lupins. They do best in well-drained, sandy soil with their deep tap roots delving for moisture

Russell lupins. They do best in well-drained, sandy soil with their deep tap roots delving for moisture

A century later, gardener George Russell noticed the lupins and thought that although the blues were dominant and very strong, their rather weak shades of yellow and rose pink could be improved. So he set about breeding a better lupin, crossing L. polyphyllus with L. arboreus and some annual species. He refused to sell his plants and destroyed all his records, but at the age of 78 agreed to allow James Baker, the owner of a nursery at Codsall near Wolverhampton, to show the plants to the public. The Russell lupins were shown for the first time in 1937 at the Royal Horticultural Society’s June show and the clear, bright colours caused a sensation.

They do best in well-drained, sandy soil with their deep tap roots delving for moisture. They grow on my heavy clay, but never reach the size they might on a lighter soil. Dead head flowers as they fade but do not cut back too hard. Lupins tend to be short-lived and resent being moved. Although easy to grow from seed, the seeds do not come true, so propagation of a particular colour combination is best done by basal cuttings in spring or splitting clumps in early spring every three or four years.

I spent the last two weeks of April in the Deep South and will be returning a couple more times over the coming few months, so naturally this is a subject that I am currently very bound up in.

The early settlers took with them all the tools, equipment and seeds they needed to establish a version of the life they had been living in England. 

With these, they forged for themselves, through huge struggle and deprivation, a harsh survival. 

But gradually they learned to harness the native plants and eventually began to send them back to England.

Francis Drake had started the process, bringing back tobacco, maize and potatoes in 1586, but the trickle became a flood with the famous father and son nurserymen both named John Tradescant. 

The elder Tradescant introduced the black walnut (Juglans nigra) and Virginia creeper (Parthenocissus quinquefolia), among many others. 

Although the father never actually visited America, the younger John Tradescant went on collecting expeditions to Virginia in the first half of the 17th century, and introduced asters, erigerons, the false acacia, the tulip tree (Liriodendron tulipifera), the red maple, the swamp cypress (Taxodium distichum) and the insect-eating sarracenia to Britain.

The relationship was continued through the 18th century by great men like Thomas Jefferson, who visited many English gardens, making notes and ordering seeds and plants for his garden at Monticello, his plantation in Virginia. 

Gardens and gardeners were exchanging plants, ideas and inspiration – including my own forebear George Don, who went to the east coast of the US in 1822 on a plant-hunting expedition for the Royal Horticultural Society.

Plant hunting in the early 19th century was characterised by intense competitive acquisitiveness, and there were always dedicated, even slightly crazy, amateurs gathering new trophies for British gardeners. 

Thomas Nuttall was a printer who in 1808 went to Pennsylvania from Yorkshire with no intention of collecting plants. 

But he soon found himself obsessively exploring unknown territory, storing seeds in the barrel of his gun. 

He brought us penstemons, artemisias, evening primroses, rudbeckias, camassias, Ribes aureum and Ceanothus thyrsiflorus.

The upshot is that your garden is bound to have American plants growing in it. 

Monticello in Virginia. American and British gardens have been bonded together by mutual plants, skills and experience ever since the first settlers founded Jamestown, Virginia, in 1607

Monticello in Virginia. American and British gardens have been bonded together by mutual plants, skills and experience ever since the first settlers founded Jamestown, Virginia, in 1607

Echinacea, witch hazel, Hydrangea arborescens ‘Annabelle’, coreopsis, Phlox paniculata, monarda, the shuttlecock fern (Matteuccia struthiopteris), and heleniums are just a smattering. 

On top of that, North American trees have changed not only our gardens but our landscape. 

SENSATIONAL MAGNOLIAS

The first magnolia to arrive in Britain was M. virginiana in 1688, brought back from the American colonies by the naturalist and clergyman John Banister. It caused an immediate stir when it began flowering, as no gardener had ever seen anything like it before. It is by no means the most glorious magnolia, being a kind of poor cousin to M. grandiflora, but it does have one of the best fragrances of all the magnolia tribe.

M. x soulangeana

M. x soulangeana

It is easy to understand the sensation it caused, because all magnolias are an astonishing exhibition of trees immodestly flowering. There is something about the combination of large, waxy petals and bare branches set against a brilliant blue sky (such as M. x soulangeana) that stops you in your tracks and upsets all notions of how plants ought to behave in a British spring. On my recent visit to South Carolina, Florida and Louisiana, the evergreen M. grandiflora, the bull bay, was everywhere, smothered with massive flowers the size of plates.

M. macrophylla is native to the south-eastern states

M. macrophylla is native to the south-eastern states

M. macrophylla is native to the south-eastern states and is deciduous but grows enormous leaves, 60-90cm long, every year. It has huge, deliciously fragrant flowers that grow to scale. It prefers lots of sun and heat but is hardy down to about -10°C if it has plenty of shelter from wind.

Many evergreens, including cypresses such as leylandii and Lawson cypress, are American, as are Douglas fir, western hemlock, thuja, sitka spruce, noble fir and the huge wellingtonias (Sequoiadendron giganteum). 

I actually had about ten of these giants lining the drive of my last garden, nearly 30 years ago. 

They must have been among the first to be planted and were part of a Victorian craze for evergreen American introductions. 

Before these hardy and dramatic trees started to become readily available in the middle of the 19th century, evergreens were rare in the UK and often tender. 

To be able to grow them outside regardless of weather or position was a great luxury.

The American star in my own garden for the past month has been a bulb which creates great swathes of colour and yet was originally an important food source of the Pacific Northwest. 

Camassias are a meadow flower with a large bulb that was harvested when the flowers were in bloom and roasted or boiled. 

Apparently they taste a little like sweet potato. I confess I have not tried eating one – and I am reluctant to do so, not out of squeamishness but because I am loath to lose any of their wonderful flowers.

The tall spires with scores of small blue flowers come back stronger year after year, and mine, mostly planted three and four years ago, are now twice the size and number they were. 

They grow in a border or in grass, although, as with all spring bulbs, the grass must not be cut until the camassia leaves have died right back. 

In my Writing Garden, which is filled with white flowers, I have Camassia leichtlinii subsp. leichtlinii, which has white flowers that last for ages.

One side of the garden is in full sun and the other in light shade and the camassias seem to be just as happy in both.

Camassia cusickii is another absolute gem. 

It is slightly smaller and the pale blue flowers with their startling bright yellow stamens appear some weeks later. 

All camassias should be planted in autumn, putting the bulbs a full 10cm deep and about 30cm apart.

It is a good idea to give them an autumn mulch as protection against hard frost.

THE MAN WHO STARTED THE RHODODENDRON CRAZE

American gardens were all the rage in mid-18th-century Britain, and a must-have was a ‘shrubbery’ boasting American flowering shrubs, particularly those that thrived on acidic or swampy soil.

Many of our popular shrubs come from the other side of the Atlantic, and if shrubberies have become unfashionable, the shrubs are most definitely not. Garrya elliptica, Ribes sanguineum, mahonia, romneya, berberis, magnolia, callicarpa, ceanothus and amelanchier are all American introductions.

Rhododendron catawbiense. The downside of R. catawbiense is that it is very similar to the dreaded invader R. ponticum and hybridises with it to make a plant that is extremely hardy and difficult to clear

Rhododendron catawbiense. The downside of R. catawbiense is that it is very similar to the dreaded invader R. ponticum and hybridises with it to make a plant that is extremely hardy and difficult to clear

The passion for American plants, which were unlike anything seen before, grew among collectors, and when a Scotsman called John Fraser (1750-1811) brought home a rhododendron, it turned out to be universally popular as it was hardy, easy to grow, smothered in red flowers and small enough to fit into most gardens. Hundreds of new varieties followed, called the catawbiense hybrids, with flowers ranging from creamy white and pink through crimson to deep purple. These then hybridised with the Indian rhododendron species that were introduced by Joseph Hooker from Sikkim in the middle of the 19th century.

By the end of the 1850s there were huge numbers of these new hybrids, and they particularly thrived in the warm, wet climate of the Gulf Stream-protected west of the UK. Great estates began to be filled with miles of these gaudy, flower-smothered shrubs. However, the downside of R. catawbiense is that it is very similar to the dreaded invader R. ponticum and hybridises with it to make a plant that is extremely hardy and difficult to clear.