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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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  • Hydrangea trial and bulletin

    Graham Rice on 30 Jan 2009 at 09:08 PM

    Hydrangea paniculata Trials Bulletin. Image: RHS Trials OfficeWhen I saw the Wisley trial of forty seven different forms of Hydrangea paniculata last September I was impressed.  These are easy and dependable summer and autumn shrubs whose shapely blooms provide attractive colour from bud to faded flower  And this week's publication of a free-to-download full colour bulletin on the trial reminds me what a wonderful sight they were.

    You may also have seen the well-established specimens on the walk up Battleston Hill from Wisley's double herbaceous border - they're stupendous.

    Hydrangea paniculata trial at Wisley. Image: ©Graham Rice/GardenPhotos.comBut until I saw the trial I'd not realised that some age far more harmoniously in colour than others.  The trial judges kept that in mind and plants were also judged for their habit, their response to pruning, for the colour of their buds, flowers and faded flowers and the shape of their flower heads, and for how their heads were held (upright or floppy); stem colour, and summer and autumn foliage colour were also assessed.  Ten proved worthy of  the Award of Garden Merit.

    But there was much more to this trial than simply judging the quality of the plants.  Two pruning trials were also carried out.

    There were three plants of each variety in the trial: one plant was pruned hard, one pruned moderately, and one simply dead-headed.  The treatments had a very noticeable effect on flowering time and flower size.  In the other pruning trial, additional plants were pruned either in February, March or April. This too influenced flowering time.

    Now, when a Wisley plant trial proves especially successful or especially interesting - as this one was - the enterprising staff of the Botany Department and the Trials Office get together, with input from the judges, to produce a report: a Plant  Bulletin.  There's a complete list of bulletins on the RHS website.  The 16 page, full colour Hydrangea paniculata bulletin is just out.

    Not only does it reveal and illustrate the results of those pruning trials but all 47 varieties are described and illustrated with AGM winners illustrated at two stages of their flowering season.  Packed with useful information, it's available as a FREE download. Read More...

  • Top dahlias

    Graham Rice on 29 Jan 2009 at 03:08 PM

    Dahlia 'Magenta Star'. Image: RHS Trials OfficeLast year the Wisley dahlia trial was one of the most colourful - and interesting - of the season. It usually is. It's always worth seeing just to admire the dazzling display. But of course there's a purpose to it: finding the best.

    Out of a grand total of one hundred and forty nine different dahlias, from The Netherlands as well as from all over Britain, just four were chosen as being good enough to receive an Award of Garden Merit (AGM). The awards have now been ratified and all four will be available to gardeners this year. And just to be clear, these are primarily garden dahlias, not show dahias, although AGM dahlias can be good for showing as well.

    Dahlia 'Mayan Pearl'. Image: RHS Trials OfficeOne of the striking things this year is that only one of the four award winners is a big traditional double dahlia - two are Collarettes and one is a single flowered variety.

    The judges were chaired by Jon Wheatley, a member of the Executive Council of the National Dahlia Society who also advises the National Dahlia Collection. "The four new AGMs this year are individually outstanding," he told me. "The single flowered ‘Magenta Star' with its dark foliage is a welcome addition to any garden. ‘Mayan Pearl' never stops flowering irrespective of the weather and ‘Trelyn Daisy', a pure white Collarette, is good for garden and exhibition . But the most interesting for 2009 is ‘Woodbridge', the first Dahlia to get an AGM for its foliage."


  • New trials blog

    admin on 27 Jan 2009 at 12:07 PM

    Wisley Trials in June. Image: Ali Cundy, RHS Trials OfficeThe current RHS Plant Finder lists over 70,000 different plants and there are vegetables and many more that never find their way into the book. But how do you know which are the best? Well, the RHS tests many of them at its garden at Wisley and gives the prestigious Award of Garden Merit to those few that outshine the others. And that's what this new blog is all about - the best plants, as proved at the RHS trials.

    Assessing the Wisley carrot trial. Image: Ali Cundy, RHS Trials OfficeI'll be bringing you news of the latest awards, highlighting the trials looking their best and noting the growing techniques which prove successful. The Wisley botanists sort out muddles in the names of the plants on trial, pest and disease problems are revealed, there are events at which you can meet the judges, bulletins and other publications appear during the season; I'll be posting about all that and more here. Sometimes AGM plants even have their awards taken away - I'll bring you that news too - as well as comments from the judges themselves.