Rosa (red roses) trial results 2021–2024

Objectives and purpose of the trial

The objectives of this four-year Rosa (rose) trial, were to specifically assess red-flowering roses. This was the first official rose trial to be held by the RHS, with previous award recommendations coming via rolling reviews. The RHS Trials team wanted to focus on red-coloured roses, as they are thought to be among the most susceptible to disease. This has made updating the list of good garden plant selections for the RHS Award of Garden Merit (AGM) a meaningful challenge.
View of the colourful red roses in the trial beds at RHS Wisley
Trial bed planted with Rosa RED FINESSE (‘Korvillad’) AGM

What is an RHS Award of Garden Merit?

The RHS Award of Garden Merit (AGM) is intended to help gardeners choose plants that are likely to perform well, and is only awarded to plants that are:

  • Excellent for ordinary use in appropriate conditions
  • Available
  • Good constitution
  • Essentially stable in form and colour
  • Reasonably resistant to pests and diseases

Judging criteria

The following factors were all taken into consideration as part of the judging of the trial:

  • General impression (plant, foliage, vigour, novelty)
  • Disease resistance (fungal diseases, pest tolerance)
  • Fragrance

  • Flower (blooms, buds, colour, abundance of flowering, recurrent bloom, post-flowering, novelty)

Red roses AGM winners

This trial was a chance to identify and showcase red roses. Although the trial faced many challenges in trying to replicate what gardeners would do at home, the trial judges were able to grant four new AGMs, reconfirm and retain four AGMs and rescind five AGMs. The list of AGMs now reflects the current availability of the best red roses to grow.

In the trial, we wanted to highlight the best roses that grow well. The four winning roses aren’t your classic cut flower, and are very much a shrub.

Michael Marriott, Rose expert and rose garden designer

Why the AGM was awarded

New AGM winners with forum comments and hardiness ratings

Rosa ETERNITY (‘Noa150097’) AGM (H6) 2024

  • Forum comment: Consistently good performer. Big and blousy. Full of flower, flowers in big clusters. Bushy growth, with healthy foliage
  • Height after four years: 150cm

Rosa LOVESTRUCK (‘Dicommatac’) AGM (H5) 2024

  • Forum comment: Vibrant. Vigorous and healthy. Lots of bushy growth. Scented flowers that fade from red to pink
  • Height after four years: 160cm

Rosa WB YEATS (‘Dicoodles’) AGM (H6) 2024

  • Forum comment: Mid-height rose, with a good habit. Lots of open flowers. Healthy, glossy leaves
  • Height after four years: 100cm

Rosa CAYENNE (‘Koroutofko’) AGM (H6) 2024 – subject to availability

  • Forum comment: Deep velvety red flowers. Floriferous. Flowers don’t scorch in the heat, and go over well. Late flowering. Vigorous. Bushy, with glossy, healthy foliage
  • Height after four years: 165cm
Reconfirmed AGMs with forum comments and hardiness ratings

Rosa MOMENT IN TIME (‘Korcastrav’) AGM (H6) 2012

  • Forum comment: A compact, low-growing selection. Floriferous. Great tonal change in flower colour. Healthy leaves
  • Height after four years: 65cm

Rosa RED FINESSE (‘Korvillade’) AGM (H6) 2012

  • Forum comment: Has impact. Very floriferous. Beautifully bushy rose, with low growing form
  • Height after three years: 65cm
Retained AGMs with forum comments and hardiness ratings

Rosa INGRID BERGMAN (‘Poulman’) AGM (H6) 1993

  • Forum comment: Did not survive beyond the first year of assessment. Identity of the plant was
    questioned. Don’t know it well enough to assess whether the AGM should be removed. Review at RHS Woody Expert Group roundtable
  • Height after four years: Unknown

Rosa MY VALENTINE (‘Korcoluma’) AGM (H6) 2012

  • Forum comment: Strong flower colour, with large individual flowers. Vigorous, with lots of tall growing shoots. Foliage healthy. Plants in the Rose Garden look better than those in the trial
  • Height after four years: 100cm
Voted AG (not quite meeting the full AGM criteria) with forum comments

Rosa Royal PARFUMA (‘Kordiagraf’)

  • Forum comment: Good flower scent. Huge plants, that didn’t defoliate. Too much disease

Rosa TIAMO (‘Korroleotu’)

  • Forum comment: Lots of flowers, that stand up to rain damage. Too much disease

Rosa PRECIOUS RUBY (‘Noa16131’)

  • Forum comment: Glossy, dark green leaves, show off the flower colour well. Plant health broke down in September each year
Judging of the red roses trial at RHS Wisley in 2022
Forum judging red roses trial at RHS Wisley in September 2024

AGMs rescinded

These selections were found to no longer be worthy of the AGM, and they will be removed from the AGM list. The forum recommended to rescind the RHS Award of Garden Merit from the following entries:
AGMs rescinded with forum comments

Rosa ROYAL WILLIAM (‘Korzaun’)

  • Forum comment: Did not meet plant health or vigour criteria. This selection has lost its vigour,
    susceptible to new strains of diseases

Rosa THINKING OF YOU (‘Frydandy’)

  • Forum comment: Did not meet plant health or vigour criteria. Only one small plant remaining in year three. Unhealthy and poor disease resistance

Rosa THE TIMES ROSE (‘Korpeahn’)

  • Forum comment: Did not meet plant health or vigour criteria

Rosa TRUMPETER (‘Mactru’)

  • Forum comment: Did not meet plant health or vigour criteria. Bright flower colour. Selection has lost its vigour and disease resistance over time

Rosa DARCEY BUSSELL (‘Ausdecorum’)

  • Forum comment: Did not meet plant health or vigour criteria. Selection has been ‘retired’ by David
    Austin

Plants and Location

What was planted?

This trial included 60 different selections of red-flowered roses from the hybrid tea, floribunda and shrub rose classifications. These were all sourced and submitted by breeders and growers from the UK, France and Germany.

Where was it planted?

Bare-root rose plants were carefully planted out in dedicated trial beds in the Trials Garden at RHS Wisley, Surrey. Here are some considerations for planting out roses:

  • Roses tolerate a wide range of conditions, but usually prefer an open site in full sun
  • Most roses thrive in soil that is moderately fertile, moist, well-drained and humus-rich

  • Plant bare root roses in late autum to early spring
  • Container-grown roses can be planted all year round

Red roses facts

There are different pruning techniques to employ depending on the vigour and shape of the rose you are pruning (rather than the classification), how the rose holds its flowers, how and where it is growing. Learn more about pruning roses >

Cultivation

Planting process

The red rose trial entries arrived at RHS Wisley as bare-root plants over the winter of 2020/2021. Most of the entries were grown on Rosa laxa rootstocks. The entries that arrived from Kordes Rosen (Germany) and Rosiers René Barth (France), were grown on Rosa canina ‘Inermis’ rootstocks.

In March 2021, three plants of each entry were planted 60cm apart in triangles across four trial beds. Drip lines were installed and the beds were mulched with strulch to act as a weed suppressor. Well-rotted horse manure and soil-improving mulch were used as mulches in the following years. The trial was fed with an organic fertiliser each year.

The plants were watered regularly in the first year, as the plants established. The watering regime was reduced over the following years, and in the final year watering only occurred in very dry spells.

To help stave off any problems, in the first year, a rose tonic was sprayed during the growing season. Signs of interveinal yellowing suggested magnesium deficiency, which is common at RHS Wisley due to the composition of the subsoil. A way to remedy this was to apply Epsom salts and kieserite. A natural spray was also used to treat aphid infestations in the first year when plants were small.

Gaps in the trial were filled over winter 2021/2022, and the younger plants were marked with a cane. Suckers were recorded and removed.

The reputation of roses as being fussy plants that need a lot of spraying and feeding should be forgotten. If you get good varieties, they are fantastic flowering shrubs that need only some fairly basic maintenance, and they will provide months of colour in return.

Janice Shipp, Garden writer

How plant health was managed

Challenges

Rust and rose black spot were the most notable diseases to affect the trial, leading to the partial defoliation of many trial entries in late summer. Some selections of roses were recorded as not ‘self-cleaning’ and hanging on to old diseased leaves. Fallen leaves were collected, and any leaves remaining on the plants over winter were picked off to slow the spread. Powdery mildew was spotted affecting leaves and some flower buds.

Dead stems with splitting bark that had broken at the base were noticed on Rosa RED FINESSE (‘Korvillade’) (F), Rosa THE TIMES ROSE (‘Korpeahn’) (F) and Rosa PRECIOUS RUBY (‘Noa16131’) (F) in 2024. Rose crown gall (Rhizobium radiobacter) was diagnosed by the RHS Plant Health team due to the swelling at the base of the stems. All three entries were removed and burned, the soil around the plants was removed and replaced with topsoil. Caliente mustard was sown in the autumn to bio-fumigate the beds before the next trial.

Grey-blue larvae were found in some of the dead stems that were cut back over winter. Some wilting flower buds were seen to have small holes in the stem below the flowers. Holes were noticed on the outside of the stems and in the centre of stems when pruned. Stem boring sawfly (Ardis brunniventris) was identified as the cause. The sawfly caused some stem dieback and loss of flowers, but the trial was not overly affected.

The trial saw various other insects, including caterpillars on flower buds and leaves, rose sawflies on leaves with characteristic egg-laying scars on stems, aphids on flower buds and leaves, rose chafers, leaf hoppers, and spiders.

Pruning and deadheading

In autumn 2021, wind rock (wind damage that can affect newly planted or establishing plants or those with weak or shallow roots) was seen in some entries, particularly those located at the ends of the rows, and these entries were pruned back by half in October. Canes were used to support the worst affected entries. Planting the graft lower into the soil would have increased the sturdiness of the trial entries, as the subsoil in the garden is sandy.

Each winter of the trial, pruning was carried out from January to February. Dead, damaged and diseased material was pruned out from every entry. Cuts were made above buds without aiming for a particular slant. The style and method of pruning were discussed and reassessed each year, to consider all the judges’ different strategies.

In the first year, roses were pruned to 40cm for shrub roses, 30cm for floribunda roses, and 20cm for hybrid tea roses. In the second and third years, one-third of growth was removed. Shrub roses were shaped with central stems for even flowering, and outer stems on hybrid teas and floribundas were pruned. Vigorous stems were trimmed for a good eye-level display. Low-growing roses were lightly pruned, with unhealthy branches cut back hard to promote recovery.

During 2022 and 2023, it was decided that one plant of each of the Kordes Rosen entries was to be pruned back harder, to 20cm from the base, as suggested by the growers. This pruning varied in results for different roses in the trial, the most vigorous entries ended the season with three similar sized plants, while for the less vigorous rose entries, it was clear which were the hardest pruned at the end of the year as they remained a lot shorter. For Rosa CAYENNE (‘Koroutofko’) (S), hard pruning helped to stabilise the plant.

Deadheading was carried out regularly during the flowering season.

Weather
In the early stages of the trial, April 2021 saw the UK’s coldest April since 1922. Summer 2022 in comparison was dry, with a record high temperature of 38.6°C registered on 19 July. The autumn saw high rainfall and mild temperatures, with no frosts recorded in November.

December 2022 was the coldest start to a meteorological winter since 2010, and plants had not been subject to gradual chilling. The lowest temperature of -8.1°C occurred on 15 December. Clear skies overnight led to intense radiation frost, which caused most of the damage across RHS Wisley.

The start of 2023 saw a second cold wave in January that lasted for 10 days. Lots of blackened and dead material was removed. The winter of 2023 was fairly mild and wet. The wet weather continued into the spring of 2024 and this was a good year for rose flowering in June.
 

Discoveries

While carrying out the trial, a lot of time was spent observing the plants, and details were noticed that did not relate to the formal trial assessment. Here are some of the interesting findings from the trial:
Rosa Charisma

2021–2024

Although the trial focused on red-flowered roses, the pink-flowered Rosa CHARISMA (‘Noa16071’) AGM was recommended for an AGM due to its exceptional performance. It stood out with its fragrant blooms, red buds that fade gracefully with age, profuse flowering in clusters, and consistent, well-shaped plants with striking red-tinted, grey-green foliage.

Watch an aerial tour of the red roses trial at RHS Wisley

Did you know?

The RHS Herbarium team collect plant specimens from each RHS Plant Trial. See the collection of red rose specimens online >

Who was involved?

Judges of the trial

The red roses trial was assessed by a 12-person judging group. From 2022 to 2024 four forum meetings a year were held from June to September. The forum was made up of gardeners, plant breeders, nursery owners, cut flower specialists and collection holders.

The red roses judges included: Kerry Austen (Chair, Rochfords International Rose Trials), Ian Kennedy (British Association of Rose Breeders), Emily Lamey (Horticulturist), Louisa Mansfield (Future Gardeners), Michael Marriott (Rose expert and rose garden designer), Daniel Myhill (National Collection holder), Charles Quest-Ritson (Author of RHS Encyclopedia of Roses), Mark Rowe (Horticulturist), Janice Shipp (Garden writer), Marilyn Stevens (Roses UK), Adam Stoter (Royal Parks) and Rod White (RHS Woody Expert Group).

Suppliers to the trial

List of plants in the trial

View all the roses trialled at RHS Wisley
  • Rosa CHERRY BONICA (‘Meipeporia’) (S)
  • Rosa ELY CATHEDRAL (‘Beajolly’) (S)
  • Rosa FRILLY CUFF (‘Beajingle’) (S)
  • Rosa FETZER SYRAH (‘Harextra’) (S)
  • Rosa PAPWORTH’S PRIDE (‘Beamelon’) (S)
  • Rosa ASCOT (‘Tan01757’) (HT)
  • Rosa BLACK BACCARA (‘Meidebenne’) (HT)
  • Rosa CARRIS (‘Harmanna’) (HT)
  • Rosa CAYENNE (‘Koroutofko’) (S)
  • Rosa CHARISMA (‘Noa16071’) (HT) (entered trial as TIMELESS CHARISMA)
  • Rosa CHARLES DICKENS (‘Raw1064’) (HT)
  • Rosa COURAGE (‘Poulduf’) (HT)
  • Rosa ‘Deep Secret’ (HT) Cants of Colchester
  • Rosa FONDEST LOVE (‘Fordest’) (HT) Style Roses
  • Rosa FRIENDS OF THE TENTH (‘Matt0619103’) (HT)
  • Rosa INGRID BERGMAN (‘Poulman’) (HT)
  • Rosa JUBILÉ PAPA MEILLAND (‘Meiceazar’)(HT)
  • Rosa LOTS OF LOVE (‘Forchriso’) (F)
  • Rosa MATTHEW (‘Simanders’) (H)
  • Rosa MOULIN ROUGE (‘Simmarg’) (HT)
  • Rosa MY VALENTINE (‘Korcoluma’) (HT)
  • Rosa PRECIOUS TIME (‘Oramarpa’) (HT)
  • Rosa PROPER JOB (‘Tan02733’) (HT)
  • Rosa RED PARFUM DE PROVENCE (‘Meiafone’) (HT)
  • Rosa ROXANNE PALLETT (‘Oradal’) (HT)
  • Rosa ROYAL PARFUMA (‘Kordiagraf’) (HT)
  • Rosa ROYAL WILLIAM (‘Korzaun’) (HT)
  • Rosa ‘Ruby Wedding’ (HT)
  • Rosa SEALED WITH A KISS (‘Simwhat’) (HT)
  • Rosa THE CAPTAIN TOM ROSE (name to be finalised) (HT)
  • Rosa THE ENGLAND RUGBY ROSE (HT)
  • Rosa TIAMO (‘Korroleotu’) (HT)
  • Rosa WEDDING CELEBRATION (‘Poulht006’) (HT)
  • Rosa LOVING MEMORY (‘Korgund81’) (HT)
  • Rosa SOPHIA LOREN (‘Spedophia’) (HT)
  • Rosa COMMANDANT COUSTEAU (‘Adharman’) (HT)
  • Rosa ARCHBISHOP DESMOND TUTU (‘Kortutu’) (F)
  • Rosa BLACK FOREST ROSE (‘Korschwill’) (F)
  • Rosa BORDEAUX (‘Korelamba’) (F)
  • Rosa DISCO QUEEN (‘Tan08171’) (F)
  • Rosa ETERNITY (‘Noa150097’) (F)
  • Rosa FLANDERS ROSE (‘Beaknight’) (F)
  • Rosa ‘Dusky Maiden’ (F)
  • Rosa THINKING OF YOU (‘Frydandy’) (HT)
  • Rosa LOVESTRUCK (‘Dicommatac’) (F)
  • Rosa MILANO (‘Korjuwko’) (F)
  • Rosa MOMENT IN TIME (‘Korcastrav’) (F) Cants of Colchester AGM (H6) 2012
  • Rosa OUT OF ROSENHEIM (‘Kormarkron’) (F) (entered trial as Calling You)
  • Rosa PRECIOUS RUBY (‘Noa16131’) (F)
  • Rosa THE TIMES ROSE (‘Korpeahn’) (F)
  • Rosa RED FINESSE (‘Korvillade’) (F)
  • Rosa REMEMBRANCE (‘Harxampton’) (F)
  • Rosa WB YEATS (‘Dicoodles’) (F)
  • Rosa THE JUBILEE ROSE (‘Poulbrido’) (F)
  • Rosa TILL EULENSPIEGEL (‘Koruhlneu’) (F) (to be released in the UK as JESTER)
  • Rosa TRUMPETER (‘Mactru’) (F)
  • Rosa WESTPOINT (‘Noa63004’) (F)
  • Rosa ‘Roundelay’ (HT)
  • Rosa DARCEY BUSSELL (‘Ausdecorum’) (S)
  • Rosa DRAGA (‘Bozdragfra’) (Frayla Series) (S)
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