Diarmuid Gavin: The thorny side of growing roses in a warmer, wetter world

Our gardens in Ireland are subject to a climate that is becoming warmer but wetter. Rain arrives in torrential downpours and the mild weather causes chaos, with many species seemingly flowering out of season. The results of this are that our plants are newly susceptible to pests and diseases. And it’s not just gardens — farmers have been hit badly this year, with land too wet to sow potato crops.

But in our gardens, I’m going to use a trusted brand of roses as an example of changes that are hitting home. David Austin is a rose breeder that has perfected the modern English shrub rose. He bred hundreds of thousands of new varieties and from them selected a small choice collection of beautiful roses, which instantly became garden favourites not only in the UK but in Ireland and the world over.

They combined the beauty of old-fashioned roses with modern disease resistance, and we have many in our gardens. But over the last few years, his nursery has taken the decision to retire some of these favourites because it is felt they are no longer suitable for our changing conditions. This means some cultivars are, or soon will be, no longer available to buy.

The most well-known of these retirements have been ‘Munstead Wood’, with its deep velvet crimson petals, and the much-loved climber ‘A Shropshire Lad’. It’s a responsible act from one of the most well-regarded nurseries in the world, and they have highlighted an important issue. There are still, of course, many beautiful and suitable varieties from the David Austin stable — one such is the gorgeous ‘Olivia Rose Austin’, named for his grandchild. When breeders name roses after family members, they are usually the best ones.

Other good varieties that they recommend as more suitable for our changing climate include the exquisite creamy white climbing rose ‘Claire Austin’, the peachy ‘Roald Dahl’ and apricot orange ‘Dame Judi Dench’. Last month, at this year’s Chelsea Flower Show, they unveiled a pretty new variety, ‘Emma Bridgewater’, which has large pink blossoms.

The best way to keep any roses safe is good gardening practice. Among the issues caused by climate change is that too much moisture and humidity help spread fungal disease such as black spot. Good air circulation around the rose is a preventative method and this is achieved by pruning. Removing overcrowded branches and density at the centre of the plant will allow for air flow.

Warmer weather also means that the aphid population increases. The recent trend has been to avoid planting roses alone as a species and instead to mix them with a more balanced palette of plants such as perennials and bulbs. Plant among other species such as marigolds and nasturtiums, which attract beneficial insects such as ladybirds, who will hoover up aphids for breakfast, lunch and dinner. When you spot aphids, remove by hand — use gloves to protect from thorns.

A healthy rose can shake off an attack from pests or disease more quickly, so prepare the ground well before planting. Dig in quantities of well-rotted manure before planting so the rose will flourish and grow vigorously. An annual mulch of compost or manure will help with fertility and moisture retention.

Plant of the week

Libertia grandiflora You’ll spot this seaside perennial in flower at the moment. Also known as New Zealand satin flower, it has stiff, upright, narrow foliage, which carries white saucer-shaped flowers on top. Salt-tolerant and evergreen, it’s a good choice for coastal gardens.

Reader Q&A

Could you please tell me how and when I can prune my Red Robin, as it is getting too tall? Thank you, Nuala

​Now is a good time. Cut back as much as you want, making a clean cut just above an outward-facing bud. Thin out any over-congested parts and anything that isn’t looking healthy. Complete the job before mid-August, as that lovely fresh red growth would be susceptible to winter frosts.

​Submit your gardening questions to Diarmuid via his Instagram @diarmuidgavin using the hashtag #weekendgarden