Skip navigation.

Graham Rice on Trials

Updates on trials and awards from the Royal Horticultural Society by Graham Rice

Recent Comments

  • Top wisterias in the trials

    Graham Rice on 30 Jun 2009 at 04:17 PM

    Wisteria sinensis 'Amethyst' on trial at Witch Hazel Nursery. Image: ©Wendy Wesley/RHS Trials OfficePlenty of shrubs and climbers have been at their peak recently including wisterias, honeysuckles, lilacs, Berberis, as well as the less well known Indigofera, Desmodium and Lespedeza, and the panel that assesses these plants have been busy.

    The wisterias were assessed at two sites near Wisley, Witch Hazel Nursery which houses one of the two National Collections, and the garden at Pyrford Court which is not open to the public. The plants have been growing for six or seven years now, this is the second year of assessment and some plants are emerging as likely AGM candidates.

    One interesting observation, which will help all of us identify mystery plants in our own gardens, was that W. sinensis, W. brachybotrys and the majority of American varieties twine in an anti-clockwise direction whilst W. floribunda and its hybrids twine clockwise.

    Amongst those rated most highly by the assessors was W. sinensis ‘Amethyst, which had developed relatively little leaf at flowering time and so showed its flowers more effectively than many. Its scent was also stronger than others and it was also noted that unpruned shoots flowered later than pruned shoots to extend the flowering season.

    W. sinensis ‘Prolific', noted as one of the most reliable, while W. brachybotrys was praised as the longest flowering of all and featured coppery young foliage.

    Wisteria brachybotrys 'Showa-beni' at Witch Hazel Nursery. Image: ©Wendy Wesley/RHS Trials OfficeThe pink flowered W. floribunda ‘Hon-beni' seemed on course to retain the AGM it received in 1993 although the best pink for colour was considered to be W. brachybotrys 'Showa-beni' but this had not flowered well last year so, at present, is not considered to be of AGM standard.

    Wisteria x formosa, a cross between W. floribunda ‘Alba' and W. sinensis raised in America more than a hundred years ago, was especially prolific


  • Sparkling berberis

    Graham Rice on 24 Jun 2009 at 04:09 PM

    Berberis thunbergii trial at the RHS Garden at Wisley. Image: GardenPhotos.comPlenty of shrubs and climbers on trial have been at their peak recently and the trial of Berberis thunbergii has been consistently colourful. These may not be the most fashionable of plants, but whenever I've looked at the trial I've been impressed by the variety of forms and the wonderful foliage colour.

    The trial is being held at Deer's Farm in Wisley village, an area only open to the public on special open days. The best of the seventy entries are becoming clear and these are proving to be a mixture of both uncommon and familiar varieties.

    Berberis thunbergii 'Clairon Rouge' at the RHS Garden at Wisley. Image: GardenPhotos.comAmongst those rarely seen ‘Boum', a seedling from France, slowly develops a rounded habit, with foliage in a striking blend of red, pink and white and was reckoned to be the best of the silver variegated types while ‘Clairon Rouge' (see image, left - click to enlarge) is a spectacularly fiery colour and would make stunning hedge. Originating in the Czech Republic, ‘Fireball' was praised for its stunning, neat, bright red leaves. ‘Orange Rocket' was impressive in its many shades of red and orange while ‘Rosy Rocket' had the tightest, most formal habit.

    Neither ‘Clairon Rouge' nor ‘Fireball' is eligible for an Award of Garden Merit at present as neither is available to gardeners. Availability is an important requirement for AGM plants - what's the point of giving a plant an award for its value in the garden if gardeners can't buy it?

    Of those which are more widely available, four stood out. ‘Admiration' has slowly become more impressive as the trial has gone on, its yellow-edged purple leaves turn crimson in the autumn. ‘Dart's Red Lady' has deep purple foliage which turns brilliant red in the autumn and ‘Harlequin' makes an upright, compact plant with relatively small leaves patterned in purple, pink and white.

    A number of different plants were entered as ‘Pink Queen' and while one was considered to be excellent and the most pink of the variegated entries, it's identity is still being confirmed.

    This is the last year of the trial, and there'll be Open Days on 15 and 29 July when you can go and see the Berberis as well as the honeysuckles and the abelias. The award winners will probably be announced in the winter.



  • Pinks Open Day and more...

    Graham Rice on 16 Jun 2009 at 01:44 PM

    Dianthus Tickled Pink ('Devon PP11') in the RHS Wisley pinks trial. Image: ©Sue Drew/RHS Trials OfficeThe forecast looks just right for the Pinks and Carnations Open Day at Wisley tomorrow. It can be uncomfortably scorching down on the trials field in the summer sun so tomorrow's forecast of cool conditions is ideal.

    The day starts at 11.30am when you can visit the trials of pinks - that's both traditional garden pinks and the miniature and dwarf pinks like ‘Tickled Pink' (in the picture). Members of the grandly titled Border Carnations and Pinks Trials Assessment Panel (that's the judges) will be on hand to talk about the trials and how it all works. You can ask them about the plants and how to grow them - it's a great opportunity to pick the brains of the experts.

    Then starting at 1.30pm there are three short talks by experts up at the Hillside Events Centre. Sue Hoy will be talking about Perfect Pinks, and demonstrating how to take cuttings; Mark Trenear will be discussing the fascinating history of pinks; while Ivor Mace will be outlining how to grow perpetual flowering carnations.

    Not only that, but the British National Carnation Society show will be taking place so you'll be able to see a wide range of perfect blooms - always inspiring - and Allwoods will have plants for sale so you can take away some plants for your own garden. It all happens tomorrow at the Hillside Events Centre near where the old glasshouse used to be  - just follow the signs. And once you're in the garden - it's free.

    Delphiniums at the RHS Wisley trial. Image: ©Ali Cundy/RHS Trials OfficeOf course there's plenty more to see on the trials field in June, this can often be the peak month of the summer. There's delphiniums, sweet peas, the annual climbers, the snap peas, the clematis, the begonias in containers and many more trials. Take the opportunity to make a note of the varieties that you find especially appealing.


  • Dwarf pinks trial - and Pinks and Carnations Open Day

    Graham Rice on 10 Jun 2009 at 05:06 PM

    Dianthus 'India Star'. Image: ©GardenPhotos.comThe dwarf pinks are coming into their peak now and the scent and colour is just captivating. But it was intriguing seeing the dwarf pinks a week or so back as they were getting into their stride. We expect pinks to flower all summer these days but exactly how they go about it makes a big difference to their impact.

    I noticed that some, like ‘India Star', ‘Red Star' (both of which already have AGMs) and ‘Starburst' simply produce new flowers just above the old ones - they look great. But others produce a flush of flowers all on one level, then the next crop of flowering shoots grows through them to come into bud 15-23cm/6-9in higher while the first flowers are still colourful - ruining the display. These included ‘Stardust', ‘Passion', ‘Slap ‘n' Tickle', ‘Sugar Plum', ‘Tickled Pink', ‘Show Girl' and ‘Romance'.Dianthus 'Show Girl'. Image: ©

    Over the rest of the summer it‘ll be interesting to see how these characteristics develop amongst the twenty three entries to the trial. And there's a also a trial of almost fifty more traditional garden pinks so don't miss those.

    And coming up soon is a great opportunity to talk to the experts about these invaluable plants. The Carnation and Pinks Open Day will be held at Wisley on Thursday 17 June 2009 to coincide with the second day of the British National Carnation Society Show in the Hillside Events Centre at Wisley.Dwarf pinks trial at the RHS Garden at Wisley. Image: ©Sue Drew/RHS Trials Office

    In the morning discuss the trials with membrs of the assessment panel down on the trials field, then in the afternoon listent to three talks by experts on pinks and carnations. And there's the show and Allwoods will be there with plants for sale. Sounds like a great day - and it's free! Just turn up.

    And for those of you can't get to Wisley, most of the plants in these trials are also being grown at East Ruston Old Vicarage Garden in Norfolk.


  • The season's first sweet peas

    Graham Rice on 05 Jun 2009 at 08:39 PM

    Sweet pea 'Aunt Jane'. Image: ©GardenPhotos.comI love sweet peas, in fact I like them so much I wrote a whole book about them, and I'm always eager for the first ones to come into flower. Picking the first few stems for the house is always a sign that summer is really here.

    So I was pleased to be able to look over the sweet pea trial at Wisley just as the first varieties were coming into flower and to make a note of those that produce the first stems for picking. Out of grand total of sixty two varieties in the trial, these were the first to produce at least one stem suitable for cutting. ‘Aunt Jane', a pale magenta from Dave Matthewman; ‘Toby Robinson', from Kerton Sweet Peas, in white with purple veining and already an AGM winner and ‘Gerry Cullinan', also from Kerton Sweet Peas, a lavender which was a star last year. Three as yet unnamed entries to the trial, two from National Collection holder Roger Parsons (who has 950 varieties in his collection!) were also pickable.

    It'll be interesting to see if these varieties also finish flowering early or if they have the staying power to last as long as the rest.

    Also just getting going down on the trials field are some relatives of the sweet peas amongst the one hundred and thirty two varieties being grown in the most extensive trial of annual climbers ever seen. There's a number of other annual climbing species and varieties of Lathyrus, a group of plants which is undeservedly passed as everyone focuses on the sweet peas, and sixteen of these are included.

    Lathyrus clymenum 'Articulatus'. Image: ©Ailson Cundy/RHSAmongst the first of these to open were Lathyrus clymenum 'Articulatus', with attractive bicoloured red and white flowers and the shorter but sparkling blue Lathyrus sativus 'Azureus'. Neither are as valuable as cut flowers as the familiar sweet peas but scrambling through low shrubs, especially when sown in the autumn in Mediterranean style gardens, they can really add a naturalistic look to the garden.

    The sweet pea trial will be well worth looking at for the nest few weeks, while the many lovely annual climbers on display will be worth a look right through till the autumn.


  • Ornamental rhubarb - send us your pictures

    Graham Rice on 01 Jun 2009 at 10:01 PM

    Rheum trial RHS. Image: GardenPhotos.comThe ornamental rhubarbs, Rheum, are dramatic flowering and foliage plants making bold specimens with, at their best, a very long season of interest. You can help the Herbaceous Plant Committee of RHS with our research on these plants.

    After the trial of ornamental rhubarbs ended in 2006 the plants were moved for further assessment and we took a look at them a few days ago. Frankly, they're a bit of a muddle. It's not as if there's a huge number of them, most of the rheums listed in the RHS Plant Finder are culinary rhubarbs. The problem is that they've become so mixed up that when you buy a plant under a familiar or promising name you've little idea of what you're actually going to get. It was clear that many of the plants we assessed were wrongly named and some good plants were not represented.

    These plants have five good features: the unfolding spring foliage can be very colourful, often dark red; the mature leaves can be impressive too, especially if they retain their red colouring on the upper surface and have an attractive shape; the flowering heads can be bold and colourful; the seed heads can also be impressive; and the whole plant can make a fine and imposing specimen.

    So we'd like you to send us pictures of really good ornamental rhubarbs. If you have plants which are especially impressive in one, some or all of these ways - please send me a picture. Tell me the plant's name, where you got it and when you got it and it will help the Herbaceous Plant Committee of the RHS understand the range of plants which are actually being grown around the country - and under what names. Please don't send plants! Just email pictures.

    Thank you! I'll report back here as we continue the research.