Yesterday I walked around the garden, noting what was in flower. In short, not much: stalwarts like Erysimum ‘Bowles’ Mauve’, Erigeron karvinskianus, Winter Heliotrope, Fuchsia microphylla, Coronilla, daisies in the lawn and some trailing Lobelia plants in a sheltered place that have escaped the frost. But, by our south-facing living room wall, our Leptospermum scoparium (Manuka or New Zealand Tea Tree) has started to flower. It will continue to flower into spring, reaching its peak in late May and June.
Leptospermum scoparium is native to Australia and New Zealand, and is a member of the family Myrtaceae, along with the Mediterranean shrub Common Myrtle, Myrtus communis, and well-known Australian plants such as the gum trees, Eucalyptus, and bottlebrushes, Callistemon. The family also contains several spices: the Clove, Syzygium aromaticum, a native of Indonesia, and the Guava, Psidium guajava, and Allspice, Pimenta dioica, both from Southern and Central America. Bog Myrtle, Myrica gale, a British native, is not a relative – it is in the family Myricaceae.
Leptospermum scoparium is thought to have originated in Australia and then spread to New Zealand, where it is now much commoner. It is a shrub or small tree, typically forming scrub 2 – 5 metres (7 – 16 feet) tall, but capable of growing up to 15 metres (nearly fifty feet). It has small, prickly leaves and pink or white flowers with five petals. It can form dense scrub and is often one of the first species to regenerate on land that has been cleared. It was first grown in the British Isles in 1772 and escaped into the wild on Tresco (Isles of Scilly) in 1935.
I bought my Leptospermum scoparium from Dover Farm Nurseries in Briston in North Norfolk in the spring of 2015. The plant was covered in a mass of flowers and it was an impulse buy. I soon found a space for it underneath the living room window, in a sheltered and sunny spot. I added homemade compost to the poor, sandy and rubbly soil before I planted it and it turns out I had chosen the ideal conditions for it. Leptospermum is hardy to about -5 degrees Celsius (USDA Hardiness Zones 9 -10, equivalent to RHS Hardiness Rating H2 – H3). It seems very happy next to the house, but I remember seeing lots of dead Leptospermum and Callistemon plants after the cold winters of 2009 – 2010 and 2010 – 2011, so I am aware I may have to cover it in severe frosts. In a colder climate, Leptospermum can be grown in a pot, in ericaceous compost. Avoid peat because of the environmental damage its extraction causes – I use alternatives such as wool-based composts.
There are lots of cultivars of Leptospermum, and L. scoparium is not the only species grown. Flower colour ranges from white to deep red-pink and there are dwarf forms as well (L. scoparium nanum). Burncoose Nurseries has photographs and descriptions of many of these. The variety ‘Red Damask‘ is a bit hardier, and is given RHS hardiness rating H4 (hardy to -10 degrees Celsius), but its flowers are partly double and I don’t particularly like them. My own cultivar was labelled ‘Lambertii‘.
Leptospermum means “thin leaves”. Manuka is the Maori name for Leptospermum scoparium. Other names include New Zealand Tea-tree, but tea tree oil comes from a different species, the Australian plant Melaleuca alternifolia, also in the Myrtaceae.
Honeybees make Manuka honey from the nectar of Leptospermum scoparium. The honey is claimed to have antibacterial properties and is a fashionable health food. It has a very distinctive taste, described as “florid, rich and complex“. I like the flavour, though whether the honey is quite worth the high price is debatable. There have been cases of adulteration of Manuka honey and beehives in New Zealand have been damaged, presumably by competitors. News of honey wars have been reported in British newspapers in recent years and there is an ongoing dispute between New Zealand and Australia over the trade marking of the name “Manuka”.
Meanwhile, in the UK, the Tregothnan Estate in Cornwall is growing Manuka and uses the leaves to make a type of tea. (Manuka tea is described as “refreshing” by the Plants For A Future website, though the leaves need to infuse longer than ordinary tea. On the Camper Mate website Adam Hutchinson recorded his experience of making some from fresh leaves, but “sadly, it tasted terrible”.)
Tregothan also produces Manuka honey on a very small scale, but with just twenty 420g jars from the 2016 season, selling at £225 each I don’t think this is any threat to Australian and New Zealand honey producers.
In our own garden, honeybees and bumblebees are attracted to the flowers, along with solitary bees such as the Short-horned Yellow-face Bee, Hylaeus brevicornis and the solitary wasp Sapyga quinquepunctata. The latter more normally visits thyme flowers, and is on the lookout for its prey, Mason Bees (genus Osmia).