Harkness Roses is a leading grower and breeder of some of our most-loved blooms. We take an insider look at the intricate work that goes into developing new varieties
Words from Peter McDermott, managing director of YouGarden nursery:
“The Harkness family has been synonymous with growing and showing English roses since 1879, crafting beautiful and resilient varieties that are grown and cherished worldwide. Breeding new Harkness roses is a meticulous and intricate but rewarding process, blending art and science.
Philip Harkness, who has been breeding roses for decades, still does so today, focussing on careful parent plant selection to ensure characteristics such as perfect growth habit, flower colour, fragrance, and natural disease resistance are built into all new varieties.
When selecting parent plants, the choice is critical because the genetic qualities of these plants will influence and ultimately define the traits of the new variety. When thinking about this, Philip always observes the potential parents with an outcome in mind – a strong growth habit may be crucial for a new shrub rose, appealing fragrance in both parents might lead to perfect perfume in the offspring and proven robust disease resistance would suggest the new variety will have great garden performance, without the need for chemicals being used by you at home.
Genetic diversity is often found to increase the chances of producing unique and resilient varieties, so crossing known parents who have that pedigree can be helpful. Philip will often select parent plants with a very varied genetic background to combine the best traits of each.
Once the parent plants are selected, the next step is to create controlled ‘crosses’. This is a process that involves very careful hand-pollination. Philip will isolate the chosen plants to prevent unwanted pollination. Then he selects healthy, mature flowers from both the seed parent (female) and the pollen parent (male).
The anthers of the pollen parent are removed to collect the pollen, which is then transferred to the stigma of the seed parent using fine brushes or tweezers. This delicate operation ensures the intended cross takes place without the possibility of cross contamination.
“By focusing on characteristics like growth habit, flower colour, fragrance and disease resistance, breeders ensure that new varieties not only captivate the senses but also thrive in gardens worldwide.”
Peter McDermott on Harkness Roses
Each cross is meticulously labelled with details of the parent plants and the date of pollination. Accurate records are essential for tracking the lineage and characteristics of the resulting seedlings. After successful pollination, the seed parent will develop rose hips, which contain the seeds of the potential new variety – the rose hips are harvested once they are ripe, usually in the autumn.
They are then cleaned and stored under controlled conditions to simulate winter dormancy. The seeds are stratified (chilled) to break dormancy and then planted in seed trays; the germination process can be slow and requires careful monitoring of temperature and moisture – plus plenty of patience!
Once the seeds sprout, the seedlings are nurtured in a greenhouse environment where they will have adequate light, water and nutrients to thrive. During this stage, Philip will begin to observe and note the
emerging early characteristics. This is quite a task because he tends to raise around 40,000 seedlings each year!
Selecting potential new varieties is a real skill and the ability to spot the true winners is an art based on extreme knowledge and many years of experience. Each seedling will be evaluated continuously throughout several growing seasons, with the final and perhaps the most critical stage being the selection of potential new rose varieties from within the vast number of seedlings.
During the first three years, more than 75% of the seedlings will be discarded because they’re not considered to be good enough, maybe because they have weak growth or because of poor disease resistance, and many more because they don’t have interesting flower form or colour.
Philip will walk the crop every week during the growing and flowering season and be on the
lookout for unique and appealing hues, consistency in colour and patterns that stand out. The
fragrance is tested for strength and appeal and roses with a strong, pleasant scent are highly valued.
Plants are exposed to common rose diseases such as black spot and powdery mildew to assess
their resistance. Only those that demonstrate strong resilience are kept. No chemical treatments are used in the Harkness trials, so any that do make the grade will be naturally resilient.
By the fifth year, from 40,000 seedlings, just 50 or so will remain. Of those, fewer than 10 will normally make it past year seven, making it a very expensive and particularly painstaking process!
Breeding new Harkness rose varieties is complex and time-consuming, requiring a deep understanding of genetics, plant care and an eye for beauty. From selecting the ideal parent plants, to making precise
crosses, nurturing seedlings and meticulously selecting the best performers, each step is crucial in
developing roses that continue the Harkness legacy of excellence.
By focusing on characteristics like growth habit, flower colour, fragrance and disease resistance, breeders ensure that new varieties not only captivate the senses but also thrive in gardens worldwide. The result
is a continuous introduction of stunning, resilient roses that embody the heritage and innovation of the Harkness name.
This year’s star – the ‘Chelsea Pensioner’ – was almost a decade in development but was heralded as a total winner, being part of the Harkness Silver Gilt-awarded display at the RHS Chelsea Flower Show in May. The rich Hybrid Tea flowers, each with up to 50 red petals, release a delicate fragrance. £2.50 from the sale of each plant goes to the Royal Hospital Chelsea, the charity-run home for retired veterans of the British Army.
Harkness Roll Of Honour
Over the years the company has launched many high-profile or now well-known roses that have captivated the nation. Among them are ‘Chandos Beauty’, a well-deserved favourite among rose enthusiasts with its strong and sweet fragrance and excellent disease resistance, and ‘Sweet Syrie’, launched at Chelsea in 2016 and deemed an all round garden performer. ‘The Duke of Edinburgh’ rose pays tribute to the late Prince Philip and has attractive double blooms on long stems, making exceptional
cut flowers for the vase.
