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May 17, 2013 6:23 pm
In the cold
There are the Tea and Noisette roses that can’t cope with much more than -5C or -10C, and there are some that can survive down to -35C or even -40C with just snow for protection.
In Moscow and Hokkaido (the northernmost island of Japan), where a low of -20C is common and -30C and below not uncommon, gardeners are still able to grow superb roses by wrapping them with a few layers of horticultural fleece supported on plastic tubing. Last summer I visited the Millennium Forest in Hokkaido where the English roses were blooming profusely in a wonderful array of colours and the air was filled with fragrance – a heady mix of old rose, myrrh, tea and fruit. In the slightly less cold gardens of the Scandinavian countries, the American Midwest and the central provinces of Canada the commonest form of protection is either conifer branches leaned up against the roses or mounding the base of the stems up with soil or mulching material.
Around the coast the problem is often not so much the cold but the extreme winds combined with very sandy soils. Some roses, however, notably the spinosissima and rugosa, are perfectly suited to these conditions. Grown inland in normal garden soil, R spinosissima, with its small creamy white flowers, black hips and very thorny stems, will quite easily grow to a height of 1m, but on sand dunes it will be just a few centimetres tall and easy to miss until you walk barefoot on to a bed of thorns. It is native to the UK and western Europe, from Iceland to Russia. Rrugosa on the other hand is more of an Asian species found growing in the coastal regions of eastern Siberia, northern China, Korea and Japan. It has large, single deep pink or purple flowers that are followed by cherry-tomato-sized red hips and is extremely thorny, like R spinosissima.
Another challenging place for roses is Patagonia. The main problem there is the strong, unrelenting wind and, while it doesn’t get too cold, the temperature difference between night and day can be vast – as much as 30C. The main advantage of this wind is that the roses are super healthy – no black spot, no aphids. The soil is blackish, full of nutrients and somewhat acid and the flower colour, mostly pink, is incredibly bright and brilliant.
In the heat
Hot climates can be as challenging as cold ones. One way to get over the problem is to enclose them in an artificial atmosphere, as they have in Gardens by the Bay in Singapore. They have built a huge 1.2Ha greenhouse where day time temperatures are kept at 24C and night time at 17C.
It is possible, though, to grow roses outside in truly tropical areas such as Bangkok, Hong Kong and Malaysia. The apricot-pink Abraham Darby, the deep-pink Princess Alexandra of Kent and the copper-coloured Fortune’s Yellow will all do well here. Pest and disease control is a big issue and spraying is essential. In Florida, however, by carefully selecting the varieties, it is possible to grow roses organically.
One of the very best groups of roses for Mediterranean or semi-tropical climates, like that of Bermuda, are the Tea Roses (not the hybrid Teas). They are distinctive with their bushy habit, beautifully shaped, nodding flowers and, unsurprisingly, often smell of tea. They flower more or less year round and vary in height from 1m shrubs to 6m-tall climbers.
All wild roses are native to the northern hemisphere, although some do come from close to the equator. Only one, the white-flowered R clinophylla, comes from the true tropics. R clinophylla is a fascinating rose found in three distinct forms. It is closely related to R bracteata, which has large white flowers and a strong pear drop fragrance, and is parent of the sulphur-yellow climber Mermaid. One of these forms grows in eastern India, on the islands of the Ganges, and so spends six months of the year submerged below the flood waters. This variety, along with R gigantea, has been used by the Indian rose breeder Viru Viraraghavan to develop a new group of varieties that can cope well with hot climates.
The only wild rose found in sub-Saharan Africa is the white-flowered R abyssinica, which grows in Ethiopia, Somalia and across the Red Sea in Saudi Arabia and Yemen. It is remarkable for its long flowering period, strong musk-like scent and health.
A hot but dry climate generally means that you will get little in the way of pests and diseases, but it does mean that at the hottest period the whole rose will shut down and the flowers may only last a day before being burnt up. However, roses are great survivors.
The most important thing to remember is that if you do want to grow roses, and want a relatively easy life, then select varieties that are most suited to your climate. If you are happy to pamper your roses then the rose world is more or less your oyster.
Know your roses: What to plant where
Recommended varieties for hot dry areas
David Austin English Roses: Darcey Bussell, Jubilee Celebration, Lichfield Angel, Molineux, Skylark, The Dark Lady, The Alnwick Rose
The Tea roses: Archiduc Joseph, Fortune’s Yellow, Homère, Mme Bravy, Papa Gontier and Perle des Jardins
Recommended varieties for hot humid areas
David Austin English Roses: Abraham Darby, Bishop’s Castle, Golden Celebration, Lichfield Angel, Princess Alexandra of Kent, The Dark Lady, Windermere
The Noisette Roses: Rêve D’Or, Crepuscule, Desprez à Fleur Jaune, Celine Forestier, Cloth of Gold, Lamarque, Maréchal Niel
Recommended varieties for cold areas
The wild roses: R. acicularis, R. majalis, R. pendulina
The Rugosas: R. rugosa, Roseraie de l’Hay, Hansa, Blanc Double de Coubert, Thérèse Bugnet
The Scots Roses: R. spinosissima, Grandiflora, Harrison’s Yellow, Double White, Mary Queen of Scots, William III
The Old Roses: Alba Maxima, Alba Semi Plena, Maiden’s Blush, Celestial, R. gallica Officinalis, R. Mundi, The Canadian Explorer
Parkland Series: Henry Hudson, Jens Munk, John Davis, Morden Blush, Morden Centenial
The following David Austin English Roses are hardy to USDA zone 4, and much colder with some winter protection: A Shropshire Lad, Crown Princess Margareta, The Mayflower, Susan Williams-Ellis, Gertrude Jekyll, Harlow Carr
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