Origanum (oregano and marjoram) trial results 2022–2023

Objectives and purpose of the trial

The objectives of this two-year trial were to assess existing and new varieties of Origanum, including both oregano and marjoram. In a change to how the herbs were assessed, the RHS Trials team wanted to test for ornamental qualities, hardiness and culinary potential to select the best plants for the RHS Award of Garden Merit (AGM).
Oregano and marjoram plants in the ground and pots at RHS Wisley
Forum judging the Origanum trial in June 2023

What is an RHS Award of Garden Merit?

The RHS Award of Garden Merit (AGM) is intended to help gardeners choose plants that are likely to perform well, and is only awarded to plants that are:

  • Excellent for ordinary use in appropriate conditions
  • Available
  • Good constitution
  • Essentially stable in form and colour
  • Reasonably resistant to pests and diseases

Judging criteria

The following factors were all taken into consideration as part of the judging of the trial:

  • Foliage quality
  • Flower quality
  • Habit and overall impact
  • Vigour and persistence

  • Pest and disease resistance
  • Culinary potential
  • Hardiness

Origanum (oregano and marjoram) AGM winners

This successful trial showcased a diverse range of oregano and marjoram plants from the genus Origanum. By evaluating the herbs based on flavour and appearance, the judges were able to grant eight new AGMs, reconfirm three existing AGMs and retain one existing AGM. Two plants had their AGMs rescinded. The list of AGMs now reflects the best Origanum currently available, both for ornamental value and flavour.

In the past, herbs such as oregano were tested for their appearance rather than culinary value. This time the trial forum members were flavour testing as well.

Paul Turner, Trial Chair and owner of Garth Cottage Nursery

Why the AGM was awarded

New AGM winners with forum comments and hardiness ratings

Origanum ‘Bristol Cross’ AGM (H4) 2024

  • Forum comment: Great ornamental example and performed well in both ground and pot. Consistent, reliable and widely available
  • Height and spread: 10–50cm X 10–50cm

Origanum rotundifolium ‘Jan’s Pink’ AGM (H4) 2024

  • Forum comment: Lovely foliage with a pretty pink flush on the stems. Colour range of the bracts is striking, from lime green through to purple-pink. Mild flavour
  • Height and spread: 10–50cm X 10–50cm

Origanum ‘Hot and Spicy’ AGM (H5) 2024

  • Forum comment: Very hardy and highly recommended for culinary use. Flavour is true to name. Attracted lots of pollinators
  • Height and spread: 10–50cm X 10–50cm

Origanum ‘French’ AGM (H5) 2024

  • Forum comment: Vigorous habit, consistent, reliable with pretty white flowers. Gentle, mild flavour
  • Height and spread: 10–50cm X 10–50cm

Origanum vulgare ‘Compactum’ AGM (H5) 2024

  • Forum comment: Well-formed smaller plants, lovely flowers, bee haven, and pleasant smell. Great value for a small plant
  • Height and spread: 10–50cm X 10–50cm

Origanum vulgare ‘Gold Nugget’ AGM (H5) 2024

  • Forum comment: Consistently performed across all seasons. Beautiful, glowing, pale gold foliage. Lovely, sweet flavour
  • Height and spread: 10–50cm X 10–50cm

Origanum vulgare ‘Pink Mist’ AGM (H4) 2024

  • Forum comment: Consistently performed. Impressive flowering with distinct small daintily formed flowers. Mild oregano flavour
  • Height and spread: 50–100cm X 50–100cm

Origanum majorana AGM (H2) 2024

  • Forum comment: Superb flavour, dries well, widely recommended in culinary circles. Perennial, frost tender
  • Height and spread: 50–100cm X 10–50cm
Reconfirmed AGMs with forum comments and hardiness ratings

Origanum laevigatum ‘Herrenhausen’ AGM (H6) 1993

  • Forum comment: Reliable, beautiful colour, good pollinator and consistently flowers
  • Height and spread: 10–50cm X 10–50cm

Origanum laevigatum ‘Hopleys’ AGM (H6) 2014

  • Forum comment: Delicate leaves with red wine coloured stems and a gorgeous tumbling habit
  • Height and spread: 50–100cm X 10–50cm

Origanum vulgare ‘Aureum’ AGM (H6) 1993

  • Forum comment: Vigorous, reliable, lovely golden late summer colour, consistent flowering. Warm, pleasant flavour
  • Height and spread: 10–50cm X 10–50cm
Retained AGM with forum comment and hardiness rating

Origanum ‘Kent Beauty’ AGM (H4) 2012

  • Forum comment: Did not perform well in the trial but it was recognised that the growing conditions were not ideal for this entry. To be assessed again in a more appropriate location for this cultivar. Delicate bracts and easily damaged. Slow to establish
  • Height and spread: Up to 10cm X 10–50cm
Terracotta pots planted with trial entries in July 2023
View of the trial beds planted with oregano and majoram plants

AGMs rescinded

These selections were found to no longer be worthy of the AGM, and they will be removed from the AGM list. The forum recommended to rescind the RHS Award of Garden Merit from the following entries:
AGMs rescinded with forum comments

Origanum ‘Rosenkuppel’

  • Forum comment: All plants present but did not meet the plant habit criteria, inconsistent form. Not recommended for alpine or culinary AGM

Origanum laevigatum

  • Forum comment: All plants present but did not meet the flower quality and overall impact criteria, lacking in flower quantity

Plants and location

What was planted?

This trial included 44 varieties of Origanum (oregano and marjoram), including sub-shrubs (deciduous and evergreen) and herbaceous perennials. All have aromatic leaves and spikes of small tubular flowers. Many can be used as culinary herbs, with others being grown as attractive ornamental plants.

Where was it planted?

The trial took place in the Trials Garden at RHS Wisley, Surrey. The plants were supplied to the RHS as 9cm pots, and each variety was planted in both the ground as well as in terracotta pots (37cm diameter) in July 2022. Here are some considerations for planting out Origanum (oregano and marjoram):

  • Plant in sunny, free-draining growing conditions, in the ground or in containers
  • Once established plants shouldn’t need additional watering when growing in the ground. In containers, the compost will dry out rapidly, so water regularly over the summer months
  • You can harvest the leaves regularly through spring and summer. Pinch out new leaves to encourage bushy growth for a plentiful harvest

  • In late spring or early summer, after the last frost, clip back established oregano plants to keep them compact and remove any shoots damaged over winter. This will encourage a flush of new growth
  • These closely related herbs share similar leaves and clusters of lipped flowers, but oregano’s stronger, spicier flavour and winter hardiness sets it apart. Both are great for pollinators

Origanum facts

Oregano has a robust spicy flavour, while marjoram is finer and sweeter. At the spicier end, you’ll find the Greek oregano and cultivar ‘Hot and Spicy’; at the other you’ll find marjoram such as O. ‘French’; and in between are golden cultivars, which are quite sweet, fine flavoured and excellent with tomatoes.

 

Cultivation

Planting process

Open ground plants

Four plants of each trial entry were planted in squares with 45cm between plants and 65cm between entries. They were grouped together as green, variegated and gold leaf plants. Barley quartzite gravel was placed on top of the entries with biodegradable mulchmat underneath to prevent weed growth.

Container grown plants

Three plants of each trial entry were planted in terracotta pots (37cm diameter) using triangle formations and multi-purpose compost. Slow release fertiliser was applied at planting. During the winter months, the pots were protected under cover in a propagation area to keep the plants frost-free.

How plant health was managed

Maintenance

Over the course of the trial, the front left plant of each entry was cut back by two thirds after flowering. All other plants were left unpruned. The RHS Trials Horticulturists noticed that the unpruned plants grew back faster each spring. This could be because the dead stems and old leaf litter left behind created a microclimate. This difference evened out later in the growing season.

Watering

The plants growing in the ground were only watered during really dry spells. The container plants were watered regularly during the summer as they dried out quicker.

Weather

The hottest day ever recorded at RHS Wisley was in summer 2022 when the temperature reached 38.6°C. December 2022 was the coldest start to a meteorological winter since 2010. The temperature dropped suddenly to -8.1°C following a mild autumn, causing frost damage. Clear skies overnight led to intense radiation frost, which caused most of the damage across RHS Wisley. In this trial, a number of plants were lost.

Challenges

The oregano and marjoram plants were generally pest and disease free. Powdery mildew and leafhoppers were present and towards the end of the season leaf spots became more of an aesthetic problem.

Discoveries

While carrying out the trial, a lot of time was spent observing the plants, and details were noticed that did not relate to the formal trial assessment. Here are some of the interesting findings from the trial:

June 2023

The trial was situated in a part of the Trials Garden with some shade cover during the day from a nearby oak tree. The RHS Trials Curatorial team noticed that the yellow-leaved selections suffered less bleaching here than in the containers that were in full sun. Plant performance was not adversely affected by the shade cover.

Did you know?

The flavour of oregano and marjoram leaves becomes more bitter after plants start to flower. For the best flavour leaves use them early in the season or chop plants back after they flower.

Who was involved?

Judges of the trial

The Origanum (oregano and marjoram) trial was assessed by a 10-person judging group during April, May, June and July, in 2022 and 2023. The panel was made up of experts with experience of oregano and marjoram as either growers, suppliers or part of the RHS Fruit, Vegetable and Herb Committee.

The Origanum (oregano and marjoram) judges included: Paul Turner (Chair, Garth Cottage Herbs), Janice Shipp (Vice Chair, garden writer), Tom Brown (West Dean Gardens), Virginia Colquhoun-Gonzalez (Horticultural Trade Manager), Diane Clement (Alpine Garden Society judge and speaker, RHS Alpine and Rock Garden Committee member), Alison Dodd (Herbs Unlimited), Holly Geipel (Horticultural Trade Manager), Ian Hodgson (garden writer, Garden News), Jekka McVicar (Jekka’s Herb Farm), Sigrid Sharp (RHS Edibles Horticulturist).

Suppliers to the trial

List of plants in the trial

View all the Origanum (oregano and marjoram) trialled at RHS Wisley
  • Origanum ‘Amethyst Falls’
  • Origanum ‘Barbara Tingey’
  • Origanum ‘Solferino’ (syn Origanum Bellissimo)
  • Origanum ‘Buckland’
  • Origanum ‘Soledad’
  • Origanum ‘Bristol Cross’
  • Origanum ‘Phillant’
  • Origanum ‘Emma Stanley’
  • Origanum ‘Dingle Fairy'
  • Origanum rotundifolium ‘Jan’s Pink’
  • Origanum ‘Kent Beauty’
  • Origanum ‘Kirigami’
  • Origanum ‘Hot and Spicy’
  • Origanum ‘Rosenkuppel’
  • Origanum syriacum 
  • Origanum laevigatum
  • Origanum laevigatum ‘Herrenhausen’
  • Origanum laevigatum ‘Hopleys’
  • Origanum calcaratum
  • Origanum dictamnus
  • Origanum majorana
  • Origanum ‘French’
  • Origanum onites
  • Origanum vulgare
  • Origanum vulgare ‘Compactum’
  • Origanum vulgare subsp. hirtum ‘Greek’
  • Origanum vulgare ‘White Charm’
  • Origanum vulgare ‘Country Cream’ (v)
  • Origanum ‘Gold Splash’
  • Origanum vulgare ‘Gold Tip’ (v) 
  • Origanum vulgare ‘Aureum’
  • Origanum vulgare ‘Aureum Crispum’
  • Origanum vulgare ‘Gold Nugget’
  • Origanum vulgare ‘Pink Mist’
  • Origanum vulgare ‘Pink Thumbles’
  • Origanum vulgare ‘Thumble’s Variety’
  • Origanum vulgare ‘Acorn Bank’
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