monarda 'Cambridge Scarlet' in one of the borders at Old School Garden,sittign well alongside a young Gleditsia triacanthos

Monarda ‘Cambridge Scarlet’ in one of the borders at Old School Garden, sitting well alongside a young Gleditsia triacanthos and Lysimachia ciliata ‘Firecracker’

With around 20 species of annuals and rhizomatous,clump-forming, herbaceous perennials, Monarda – or ‘Bee Balm’ because of it’s value in treating bee stings- would be a relatively small genus, though it also has many garden-worthy, hardy hybrids.

Hailing from North America, and otherwise known as ‘Bergamot’, Monarda like sun, but will grow in dappled shade too, but plants established in partial shade or filtered sun have higher incidences of rapid horizontal spread and flower less. Their natural habitats are the dry prairie and also woodlands, so they vary in their soil requirements from those that like a dry soil to those liking moisture – all need moisture retentive soil though and if the soil is too dry they are prone to mildew, as they are here in Old School Garden. It can also tolerate clay soil. The incidence of powdery mildew can be reduced by allowing good air movement between plants, ensuring the soil does not dry out, removing diseased leaves and stems to destroy the overwintering stage of the fungus and choosing mildew-resistant cultivars. Fungicides or horticultural oils can also be used to control powdery mildew.

Generally, propagation occurs by hardwood and softwood cuttings, root cuttings, layering, and division. The latter, quite frequently, is the most popular method out of necessity:  on soil that stays moist, plants can spread fairly quickly so the plant should be divided every 3 to 5 years to reduce spread, keep the central core of the plant healthy, preclude root rot, and improve air circulation about the foliage.

The flowers are a delight, arranged in whorls, rather like sage. They are tubular, with 2 lips, an upper one that is hooded and a lower one that spreads and they often come with coloured bracts. The plant is long flowering, from mid to late summer, and blooms almost continuously if deadheaded periodically. The blooms make excellent cut flowers, both fresh and dried.

Wasp on a Monarda punctata

Wasp on a Monarda punctata

Being attractive to bees and butterflies it is a good plant for wildlife gardens, though only Bumble Bees can gain direct access, honey bees and other insects getting in only after something larger has made holes!  Because of oils present in its roots it is sometimes used as a companion plant around small vegetable crops susceptible to subterranean pests. Bee balm is considered a good plant to grow with tomatoes, ostensibly improving both plant health and tomato flavour.

Ranging in height from 20–90 cm (8–35 in), Monarda have an equal spread. The stems are distinctive, in that they are square in profile, and taller varieties often require staking. The slender and long-tapering (lanceolate) leaves are not particularly striking to look at but are aromatic and are a definite reminder of ‘Earl Grey’ Tea, which is flavoured with Bergamot and the leaves are sometimes picked for pot pourri. Slugs can attack new growth in the spring but the genus is low in allergens.

Most hybrids are derived from Monarda didyma or M. fistulosa.There are over 50 commercial cultivars and hybrids, ranging in colour from post – box red to pure white to deep blue, but these plants tend to be smaller than wild species, and have often been developed to combat climatic or pest conditions. Other hybrids have been developed to produce essential oils for food, flavouring, or medicine. The following cultivars have gained the Royal Horticultural Society’s Award of Garden Merit (AGM):

  • ‘Beauty of Cobham’(pink)
  • ‘Gardenview Scarlet’
  • ‘Marshall’s Delight’ (pink)
  • ‘Squaw’ (red)
  • ‘Talud’ (pink)
  • ‘Violet Queen’
Monarda citriodora ('Horse Mint')

Monarda citriodora (‘Horse Mint’)

Monarda are great perennials for meadows and wild gardens, along streams and ponds, in woodlands and also in the garden border. The boldness of bee balm makes it equally good for massing or as an accent, and it mixes well with other summer perennials such as phlox, iris, day lilies and yarrows. The long season of colour attracts bees, butterflies (and in North America, hummingbirds) and these will capture your attention as well.

Monarda also looks good with:

  • Veronica ‘Blue Charm’ which bears spikes of light blue flowers at the same time as bee balm. The habit and flower shape contrast well.
  • Aster – masses of small, pale blue flowers appear in summer on heart-leaf aster and provide an airy contrast to bee balm.
  • Coneflower (Echinacea) – the large daisy flowers of purple coneflower mix well with those of bee balm, especially in sunny wildflower gardens.
  • Evening Primrose (Oenothera) – blooming in summer, the clusters of yellow goblet flowers of common sundrops mix well with bee balm, especially the mahogany-colour varieties.
  • Astrantia major ‘Ruby Wedding’
  • Persicaria ”Red Dragon’

Sources and further information:

Wikipedia

‘The Monarda Speaks’- blog article

Monarda citriodora (Horse Mint)- video from Texas

Monarda and powdery mildew resistance- University of Chicago study

Old School Gardener

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