• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

To discuss hibiscus

Preparations are underway for a riot of summer colour on the trials field, with exotic hibiscus and sunflowers set to bloom against a lobelia sky

Pruning the hibiscus trial at RHS Garden WisleySpring has now sprung and we are extremely busy pruning, planting and edging on the trials field. I’ve just pruned my Hibiscus syriacus trial to provide good strong plants and colourful displays later in the year.

This is a four-year trial 'Euro-trial', with the same hibiscus cultivars trialled in eight European countries. We are lightly pruning two plants of the three shrubs in each entry to open up the plant’s centre. This pruning technique improves the shape, provides good air circulation to help prevent fungal diseases and, by reducing the number of branches to around five per plant, encourages a strong framework.

We are pruning the third plant in each entry down to three buds as an experiment, which is to see how they respond to more rigorous pruning methods. In this case, it’s important that the top bud is outward-facing, so the shrub grows outwards into a rounded, vase-like shape.

The Hibiscus Forum is assessing these plants four times a year to consider how each plant performs. Some hibiscus trial cultivars already have the Award of Garden Merit (AGM), including ‘Hamabo’, ‘Meehani’, ‘Diana’, ‘William R Smith’, ‘Oiseau Bleu’, ‘Notwoodone’ and ‘Woodbridge’. These cultivars are included to give a benchmark standard for comparison and also to see if these are all of AGM standard compared with newly-introduced cultivars.


Planting up the modules for the living wall of lobelia

Planting blue skies and summer sun

Another project I am working on is building a living wall of bedding lobelias (Lobelia erinus). This will provide a colourful backdrop to my sunflower trial in pots. I am using various shades of blue to give the effect of a summer sky in the background. The living wall is a modular tray system that hangs vertically on the fence.

Made of 40 trays filled with soil, it is planted up with 640 plants and will stay in our propagation unit for a month to establish a strong root system before they are hung on the fence. Come back and see the progress during the summer!

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