There are not many native trees and shrubs that are grown primarily for their flowers – kowhai, manuka and hebes top the list – so it is nice to have some that provide blossom at this time of the year. Among the best for this are the various hybrids derived from the New Zealand manuka, with a range of colours in the white, through to red, range.
Most New Zealanders think of manuka as being the stereotypical New Zealand plant and are probably a little surprised to learn that it originated in Australia [where most of its close kin are found] and was probably blown across to New Zealand on a brisk northerly breeze as seed. Until human settlement, it was probably not to be found much, but the forest clearances by both Maori and Pakeha gave it the opportunity to expand its range here, and it is now more common in New Zealand than across the ditch.
It did not take long for gardeners to realise there was quite a range of genetic diversity in New Zealand plants and different coloured forms were quickly selected to bring from the wild to the garden. As early as the 1880s, a red-flowered form was found on Signal Hill in Dunedin, and seedlings were raised from that. Most of the red-coloured forms derive from a plant found growing on a farm near Kaiapoi around 1900. Cutting material was provided for a local nursery, but the wood was not at the right stage. Fortunately, the nurseryman sowed some seed. Even then, of 100 seedlings, just seven had either red or dark pink flowers, and it is from these that most in the range descend.
Oddly, much of the work undertaken to improve the flowering power of manuka has been undertaken overseas, with Australian and American breeders playing a large part in increasing the flower size and introducing double flowers.
One type of manuka largely derives from work undertaken at the once-famous New Plymouth nurseries of Duncan and Davies. They took the very low-growing form ’Nanus’ and raised many seedlings, some of which they introduced under the names of various birds – ‘Kiwi’, ‘Tui’ etc. These are generally low-growing plants with small flowers, ranging from white through to light red. However, I must confess that I have one of these “dwarf” cultivars, given to me by a now-deceased gardening friend to commemorate my daughter, and it has grown well over two meters tall, and needs frequent trimming back!
There are some prostrate [or at least nearly so] varieties on the market. ‘Pink Cascade’ has quite large flowers with prominent pink bars along each of the petals, giving a solid pink effect. It is nearly prostrate, and with a little judicious trimming, can be encouraged to become more so. ‘Red Falls’ is similar, but with deeper coloured flowers. Both are great on the edge of retaining walls, or in similar places. I have also seen them grafted to make weeping standards, but I am not convinced that the process works that well.
I think the double-flowered forms are among the prettiest of our natives. They almost all have very frilly flowers with many layers of petals and come in a full range of colours.
We used to grow ‘Snow Flurry’ which has beautiful white flowers, carried with exuberance. I liked to trim the plant to keep it tidy, but I quickly discovered that this cultivar flowered so abundantly that a strong rainfall would fill the flowers so much that the weight would make the young branches droop over and even break.
There are nice pink forms – ‘Rosy Morn’ is as pretty as any – and even one for those who cannot make up their minds whether they want a pink one or a white one – ‘Sunraysia’ has a mix of colours, ranging from white through light to dark pink, all at the same time. ‘Jubilee’ is another pretty pink form that flowers in spring.
Some years ago, Jack Hobbs in Auckland bred a range of more compact growing plants, better suited for growing in the north. They were released under the series name if ‘Wiri’ followed by a ladies’ name – Donna, Linda, Susan, Kerry, Joan etc. The last is a pretty form that flowers over winter with fully double bright red flowers.
Manuka is generally easy to grow in the garden and don’t take too much looking after. However, we now need to keep an eye out for myrtle rust, because it has been found in Wairarapa and is known to affect this plant. You will see little yellow pustules, at first on the underside of the leaves, then on both sides. There is no cure for this disease yet, so if you see it, destroy the infected plants.
