• 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

Pelargoniums on parade

The Trials Department gets ready for its Pelargonium Trial this summer - come and help us select the best


Did you vote for your favourite sunflower as part of the People's Choice Award last year? This year, visitors will get to vote for their favourite in our Pelargonium trial, planted in containers near the Hillside Events Centre and in the ground on the Trials Field at RHS Garden Wisley. Some of the container entries will also be on display at Royal Botanic Gardens Kew. We are looking at the Zonal group, which are mainly derived from Pelargonium inquinans and P. zonale, although there are some interspecific cultivars in the trial too.
 

Pelargonium CitronellaPelargonium or Geranium?

Pelargonium is a genus of over 200 shrubby or herbaceous species, mostly native to South Africa. Zonals are upright, bushy, succulent-stemmed perennials, grown for their single or double flowers. Some have attractive foliage. This type is most familiar to gardeners as container and summer bedding plants. Confusingly they are incorrectly referred to by the common name, geraniums.
 
Geranium RozanneSwedish botanist Carolus Linnaeus originally included all the Pelargonium species under Geranium in his Species Plantarum of 1753. Although the French botanist L’Héritier defined the differences between the two less than forty years later, the name stuck and the confusion has continued ever since.
 
Geraniums, often called cranesbills, have flowers with five very similar petals, and so are radially symmetrical, with ten fertile stamens.

Pelargonium flowers have two upper petals which are different from the three lower ones, creating a single line of symmetry, have a nectary tube and not all ten stamens are fertile.  
 

Organising the trial

young plants under glassHundreds of rooted cuttings arrived at Wisley just after Easter from five different companies. Some of the entries will be in the ground, some will be in containers and some will be in both. There was lots of sorting and organising to be done especially as the list of promised plants did not always match what was sent.

Unfortunately the label printer broke so over 1,300 plant labels had to be written out by hand! It took us two days to sort, pot on and label all the cuttings. They’ll stay in the Propagation Unit until the beginning of June.

We hope to have more plants arrive from a sixth company at the end of May so there should be up to 74 entries in containers and 87 in the ground at Wisley. There should be a range of single-flowered (with five petals), semi-double-flowered (six to nine petals) and double-flowered (more than nine petals) cultivars in white, red, orange, lilac and numerous shades of pink. Do come to see them from the end of June onwards and choose your favourite.
 

Useful links

Growing Pelargoniums
RHS trials

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