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Graham Rice on Trials

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

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  • Amaranthus - bold and beautiful

    Graham Rice on 30 Sep 2009 at 10:34 AM

    Amaranthus 'Golden Giant' in the trial at the RHS Garden at Wisley. Image: ©GardenPhotos.comWe all know the old cottage garden annual Love Lies Bleeding, Amaranthus caudatus. But down on the Wisley trials field right now is a trial of these impressive and easy-to-grow annuals - with almost thirty other entries alongside that familiar favourite.

    They come in an amazing variety. As well as the long deep red tassels of Amaranthus caudatus there's a pale green form and a spectacular range of type with upright plumes in crimson, green, and biscuit brown plus some with tight, upright rather nobly flowers heads. There's also a range of varieties with coloured foliage.

    One striking thing about the trial is that the mixtures are all noticeably poor compared with the single colours. They vary so much in height and style of flowering that in a group they just look terrible. So forget about ‘Mixed', ‘Ribbons and Beads' and ‘Pony Tails'.

    Amaranthus 'Oeschberg' in the trial at the RHS Garden at Wisley. Image: ©GardenPhotos.comAmongst the those with biscuit brown plumes ‘Golden Giant' (above) was definitely the pick. ‘Marvel Bronze' features tall deep red plumes and bronze-red foliage which makes a great combination as does the rather similar ‘Oeschberg' (left).

    A few varieties of the less robust Amaranthus tricolor were also included, these are the ones with multicoloured foliage but insignificant flowers. ‘Early Splendour' was probably the pick but they all develop a rather ungainly habit and none had the impact of the flowering types.

    One thing to keep in mid is that most of these make big plants - 90cm-1.2m/3-4ft is common so they need space. But in a large container, slipped into spaces in mixed borders or as part of a tropical style summer border these are very effective.

    You'll enjoy seeing these impressive annuals, take a stroll down to the trials while they're still looking good. And there are voting forms at the back of the Trials Pavilion so you can tell us which is your favourite.


  • Late flowering pinks

    Graham Rice on 23 Sep 2009 at 08:39 AM

    Dianthus 'Gran's Favourite' - still flowering in mid September. Image: ©Whetman PinksOne of the benefits of looking over the trials regularly through the season is that it's possible to pick up points that would be missed by simply checking the trials while they're at their most colourful. So the other day I cast my eye over the trials of pinks, three months after their peak flowering period, to see which varieties were still performing well.

    In general it was very obvious that the dwarf pinks, most of which are relatively new varieties, had far fewer flowers than the garden pinks - most of which have been around for a few years.

    So the two with the most impact at this late point in the pinks season were ‘Gran's Favourite' (above) and ‘Houndspool Ruby' (below left), both well known varieties and both already holding the Award of Garden Merit.

    Dianthus 'Houndspool Ruby' - still flowering in mid September. Image: ©Whetman PinksOthers that stood out were ‘Doris', ‘Moulin Rouge' and ‘Valda Wyatt' - again all three already hold the Award of Garden Merit and I expect that these long flowering qualities have already been noticed by the experts who've been assessing this trial over the years.

    As I say, the more modern dwarf pinks were less impressive this month compared with June and July but the three that featured the most flowers were ‘Red Star', ‘Passion' and ‘Starburst'

    But the lesson seems clear. If you'd like to have pinks which are not only covered with flower in their peak period in early summer but which carry on their display into the autumn, choose AGM winning garden pinks like ‘Gran's Favourite' and ‘Houndspool Ruby'. But remember too: all pinks will flower more prolifically if regularly dead-headed



  • Dazzling celosias

    Graham Rice on 16 Sep 2009 at 10:48 AM

    Celosia trial at the RHS Garden at Wisley. Image: ©GardenPhotos.comCelosias used to thought of mainly as pot plants, and they were also favourites for decorating events at town halls and other municipal venues.

    But I grew celosias as summer annuals in mixed borders a few years ago and they were superb. As the summer climate improves and as more adaptable varieties are introduced, growing a trial out in the open on the trials field has provided one of the most colourful of the summer's trials. They come in two types, the feathery plumes of the Prince of Wales Feather type, and the Cockscomb type with congested flower spikes that, some people say, look like the inside of your brain!

    Forty eight entries were grown, all started from seed in March and treated as half-hardy annuals. Most were of the feathery type and come in vibrant red, orange, gold and yellow shades and their dazzling colours catch the eye as soon as the trials come into view. There are a few softer colours, though these seem less effective, and one lovely tall pink and white form.

    Looking them over yesterday, we had an eye for both flower and foliage colour, long flowering season and an effective display of plumes. Uniformity is also important, in two ways: there should not be too much variation in colour of the single colour types and if the flowers were supposed to be feathery plumes there should be no cockscomb types creeping in to spoil the impact.Celosia 'Flamingo Feather' in the Celosia trial at the RHS Garden at Wisley. Image: ©

    There were five which especially caught the eye of the assessment panel. ‘Smart Look Red' featured long lasting bright red flowers set against rich burgundy foliage to create an unforgettable combination. The vivid slightly pinkish red spikes of ‘Glow Red' were much admired while ‘Century Red' was neat enough for small containers or small sunny beds around the patio with bronze foliage setting off the bright red flowers. The vivid marmalade coloured plumes of ‘Fresh Look Orange' were very striking set against fresh green leaves.

    ‘Flamingo Feather' (above, click to enlarge) was rather different, taller than most of the others and with masses of slender spikes, the carmine buds open to pink flowers fading to white. Good for cutting, it also integrates especially well with perennials in mixed borders.

    The assessors rated those five especially highly, but you can vote for your own favourites. Pick up a voting form in the new logia at the bottom of the trials field, make your choice, add your comments and leave it in the box alongside the celosia trial itself.



  • Kniphofia (red hot poker) Open Days

    Graham Rice on 07 Sep 2009 at 10:39 PM

    Alongside a new look Wisley Flower Show, starting this coming Friday morning and closing on Sunday afternoon, the RHS Herbaceous Plant Committee is running a series of three Kniphofia Open Days. Kniphofias are dramatic, colourful, sometimes statuesque perennials which are currently enjoying a revival so this is an ideal time to combine a visit to the Wisley Flower Show with finding out more about these essential autumn perennials. There are two parts to the event.

    Kniphofia 'Bees' Sunset' in the Kniphofia trial at the RHS Garden at Wisley. Image: ©GardenPhotos.comIn the loggia at the end of the Wisley Canal, just a short walk from the main entrance to the Wisley Garden, there'll be a series of illustrated display boards giving a thorough and easy-to-follow introduction to kniphofias. Members of the RHS Herbaceous Plant Committee will be on hand each day to provide expert advice so, to mention just three, you'll get the chance to pick the brains of Sarah Cook, former Head Gardener at Sissinghurst, Ivan Dickings former Chief Propagator at Notcutts Nurseries and plant breeder Simon Crawford.

    They'll be able to tell you about where kniphofias grow in the wild, how best to grow them in gardens, which varieties did well in the trial and answer your questions about kniphofias, how to grown them and the plants that look good with them.

    Also, at 11am and 2pm each day, meet at the loggia for a Guided Walk through the Kniphofia trial where you'll be able to see every one of the one hundred and twenty seven (yes, really - I know, you had no idea there were so many!) entries in the trial and get an insight into why some got high marks in the trial and some did not. There'll be some stupendous varieties at their peak.

    So that's Friday 11th, Saturday 12th and Sunday 13th of September - start at the loggia at the end of the Wisley canal: enter the gardens, turn right along the back of the main building and look to your left towards the end of the canal.



  • Annual climbers

    Graham Rice on 02 Sep 2009 at 12:40 PM

    Rhodochiton atrosanguineum - in the Wisley Annual Climbers trial. Image: ©GardenPhotos.comMost trials concentrate on a particular type of plant - usually one genus like Dahlia or Dianthus. But occasionally a whole group of similar plants from a wide variety of genera is trialled together because they have useful similarity - and this year it's the annual climbers.

    These are invaluable  in creating a quick feature in a new border, rapidly clothing a fence or wall, or for adding a secondary colour to a mature shrub or climbing rose.

    There are one hundred and fifteen different entries covering about twenty different genera grown on wire towers and they've been fascinating. The site is perhaps a little too exposed for some of them, but many are thriving - indeed the Eccremocarpus are thriving a little too enthusiastically, they're very vigorous and the rich soil is helping create large plants.

    Not many years ago Rhodochiton astrosanguineus (above) was mainly grown in pots in the cold greenhouse as it was considered impractical to grow it outside - on the trial, it thrives. In recent years more robust forms have been selected.

    Ipomoea 'Heavenly Blue' - in the Wisley Annual Climbers trial. Image: ©GardenPhotos.comOf the forty Ipomoea entries, ‘Bohemian Shades', ‘Grandpa Otts' and I. lobata stand out with many of the others also impressing. ‘Heavenly Blue', however, is not showing itself off as well as we know it can and the judges described ‘Split Personality'  as "ugly"!