• 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

Now showing: a plethora of peonies

Peonies are incredibly useful for providing colour in the gap between the spring and summer flowers. We're testing out 170 varieties, so if you're thinking of planting one, why not visit our peony trial?

When the spring flowers have gone but the summer bloomers haven’t yet taken over, gardens can lack colour, and peonies are a great option to 'bridge the gap'. So if you are considering buying one one for your garden, there's no better place to start than the peony trial at RHS Garden Wisley. Although this is the first (establishment) year of the four year long trial, there are plenty of plants in flower.

Peony ‘Pink Hawaiian Coral’The trial takes place in two locations. Most of the plants are in the Trials Field in a formal trial arrangement, but a selection of peonies can be found on Seven Acres in a garden setting.

There are around 170 different peony entries being trialled. They are split up into three groups*: herbaceous peonies, Itoh hybrids and container peonies (suitable for growing in pots; selected for their compact growth).       

What's an Itoh peony?

Itoh peony 'Morning Lilac'In case you are holding your head, asking yourself what on earth is an Itoh hybrid, here is a short explanation:

Itoh peonies, also known as intersectional hybrids are crosses between herbaceous and tree peonies. They were named after Toichi Itoh, a Japanese breeder, who managed to create the first ever cross between a tree and a herbaceous peony. Unfortunately he died before the flowers of his new cross appeared, but the breeding work didn’t stop and there are plenty of different Itoh hybrids on the market these days.

Itoh peonies combine the good characteristics of both tree and herbaceous peonies including:

  • Herbaceous growing cycle: stems die back in the autumn, so it doesn’t leave a bare shrub for winter. Grown in the same way as herbaceous peonies.
  • Stronger stems which are able to hold the flowers upright without staking.
  • Vigorous and floriferous: a mature plant can produce up to 50 flowers in a single season.
  • Enormous flowers (up to 20cm / 8in across).
  • Extended blooming period due to additional flowers being produced on side shoots.
  • Great winter hardiness.

Historically, intersectional hybrids were challenging to propagate and were therefore extremely expensive. But thanks to recent breeding efforts Itoh peonies are more affordable today.

If you missed the gorgeous but short-flowering peonies, there are several other exciting RHS plant trials coming up and worth visiting in the summer, including Zantedeschia, Echinacea and strawberries.

*Tree peonies are not included in this trial.

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