Roses and climate change

In the past couple of years, as co-editor of By Any Other Name, the heritage rose journal of the World Federation of Rose Societies, I have begun to travel much more to see roses. Wherever I go the subject of climate change is seldom far from people’s concerns.

The rose is an incredibly adaptable genus, growing wild from the Tropic of Cancer to the Arctic Circle. But different climates can have a huge impact on how well it grows.

Heat effects

Thomas Proll, head of the breeding department at W. Kordes’ Söhne, tells the story of a bright orange bush rose he hybridised at the company’s nursery at Sparrieshoop in the north of Germany in 2008.

He says: “It was a nice rose, but it was a lazy bloomer in Germany. The first flush was only single flowers. It wasn’t floriferous enough to be a great, great rose.” Reluctant to give up on it, he sent the rose to Ludwig Taschner, Kordes’ distributor in South Africa. He was taken aback when Taschner expressed his enthusiasm for it. “Taschner said it flowered all through the season in Pretoria, with masses of blooms – like a wall of flowers,” says Proll.

Taschner suggested the name ‘Afrikaans’. Proll sent the rose to Australia, where it performed similarly well, winning the People’s Choice Award at the National Rose Trial Garden Awards of Australia in 2021.

The veteran Australian rose breeder, George Thomson, once invited Britain’s David Austin to his nursery in South Australia. He said: “We were walking around when he stopped by a tree and looked up at a rose growing high up into it. He frowned and just stared, then said: ‘That looks like my rose, ‘Graham Thomas’, but it can’t be. It doesn’t climb that high.’ ‘It does here,’ I said!”

Drought and damp

Heat can clearly be good for some roses. The bigger issue may be the damp. Changing climate is forcing many gardeners around the world to rethink how they do things. Our gardens may need to be able to endure drought and heavy rain. Spain has seen terrible flooding in recent weeks. Yet, before that, parts were battling with the lowest rainfall in 160 years. The international judging of the Barcelona rose trials was cancelled in May this year because the drought conditions had become so difficult.

At the 2023 trials, Gabino Carballo Pérez, from the Barcelona Parks and Gardens Department, spoke of the challenges. He said: “I think that in less than a decade some areas of Spain that are currently fertile will be arid and unproductive. As water tables fall you get aquifer contamination; water quality drops and salinity rises. The soil degrades over time and you have a crust of salt that puts the roses under long-term stress. We will see then which rose varieties survive and which fail.”

He believes people will have to prioritise between watering the garden and filling the jacuzzi or swimming pool. Parks and public roses gardens could become precious oases. He said: “As the crisis deepens and we become more aware of the lack of resources I think we will see the importance of our rose heritage and of the cultural value of parks and gardens, which may lead to us investing in them. We will probably have fewer but perhaps they will be better quality.”

India

The great Indian rose breeder, Viru Viraraghavan, who died last year, had an unusual way of seeing the impact of climate change – watching plants like Tithonia diversifolia and blue-flowering morning glory (Ipomoea indica) climb mountains near his home in Kodaikanal on the Palni Hills – an eastern offshoot of the Western Ghat mountains.

He told me: “They used to be confined up to 1500m but in the last decade they have climbed the mountains and can be found up to 2200m. There can be little doubt that considerable warming has taken place here. What has happened with Lantana camara is quite extraordinary. Originally, when we first moved to Kodaikanal in 1980 we noticed that the flowers were a lilac pink colour in the upper plateau but as we went down the mountain side to around 1200m the colour changed to orange. In more recent times the orange flowered version of the lantana started appearing even at the altitudes of the upper plateau.”

For many years Viru and his wife Girija bred roses specially designed for climates like India’s. Maybe European rose breeders will start taking more interest in their work soon.

Testing times

Breeders are determined to ensure that the rose maintains its position as the world’s favourite flower, whatever conditions it is grown under. That means making them more resilient to climate change and to disease. And that means testing them rigorously.

Matthias Meilland belongs to the sixth generation of the famous French rose-breeding family. The Meilland company grows its most promising new roses in private test beds around the world that he calls “rose hell” – a process it began in 1935. In none of them are pesticides or fungicides used today. Nor are they watered once established. In the south of France they are subject to 45 degrees Celsius heat and 70 days without rain. In Germany, the roses are exposed to sodden soil. In Pennsylvania the field is rife with blackspot. Down in California they have to survive drought and heat. In Kenya they test cut roses not just for how well they grow under glass, but how well they survive shipping.

Meilland says: “We want better roses that can cope with climate change and that are more disease resistant and more floriferous. We take traits from existing roses that we think future gardeners will like and try to carry them over on to stronger plants. We’re trying to create plants that will last 100 years.”

Who knows what the next 100 years will bring in terms of climate? It is almost too worrying to think about. But nature is resilient. The earliest rose fossils date back around 35 million years. This is a plant that has seen it all before and survived. Hopefully it will continue to flourish for many more – and our descendants will be here to enjoy them.

Banner image: Judges at international rose trials test plants for their quality and health Réunion (2019). Image courtesy of Meilland Roses