The diversity of New Zealand’s flora is, in large part, due to the kaleidoscope of landscapes that we possess. Ranging from sub-tropical forests in the north to the alpine herbfields of the South Island, our country provides us with a myriad of ecologies to study and use as inspiration for making gardens. Amongst the most interesting of these are the subalpine scrub and dry grasslands that characterise the Mackenzie Basin and nearby natural areas (such as Aoraki/Mt Cook National Park).
These two habitats serve as the basis for the planting at this Tekapo garden, whilst a degree of seasonal variation and colour is interwoven into the native framework, by the addition of flowering exotics which include paeonies, ornamental onions (Allium spp.) and the spectacular foxtail lily, Eremurus. The naturalistic planting design enabled us to incorporate a significant range of rare and unusual native species. Plants of particular local significance include the threatened shrub Leonohebe cupressoides, the climbing broom, Carmichaelia kirkii, and the coral broom, Carmichaelia crassicaulis, a highly unusual shrub which is becoming increasingly rare within the dry South Island habitats to which it is native.
The landscape of the Mackenzie Basin is a difficult place for plant growth. Those species that endure within the moraines and dry grassland that characterise this part of the country display a resilience which is a great advantage in garden plants for the South Island’s dry eastern regions. Several of these form the backbone of the more exposed situations within the garden. One of the most interesting and useful local species is the so-called porcupine bush, Melicytus alpinus, a sprawling shrub which forms hummocks throughout both native and farmed parts of the Mackenzie Basin landscape.
In addition to buying nursery-grown plants of this species, we collected and propagated local material, from cuttings off wild plants that occur on private land within 100m of the house site. We also sourced cuttings of a closely related, upright Melicytus with particularly dark leaves (which grows in excess of 1.5m). This form, which corresponds most closely to a form described in Eagle’s Trees and Shrubs as Melicytus aff. alpinus (vii), shows potential of being an exciting garden plant that, as far as we know, is currently unknown within cultivation.
The remarkable coral broom (Carmichaelia crassicaulis) is a member of degraded habitats within the local area; although it is less frequently seen in the wild than M. alpinus, due mostly to the attentions of browsing mammals. Both sub-species of the coral broom are planted within the garden, where they lend a sculptural character to the upper slope of the garden. The scented tree daisy, Olearia odorata, is another locally-occurring native shrub that survives difficult conditions within nature. Several specimens of O. odorata and its close relative, the critically endangered Olearia adenocarpa, contribute towards forming the structure of the garden.
Mingling with the base of these is one of the most overlooked plants for cold, dry areas of New Zealand, Pimelea traversii. This wonderful, compact shrub bears attractive heads of white flowers at the end of its bluish-leaved stems over the course of summer.
The garden contains a significant range of species from Carmichaelia and Olearia, with both genera very well adapted to dry conditions. Of the brooms, Carmichaelia petriei commands attention for its bright green branches and stiff upright growth. Although not local to the area, we have also planted several specimens of two Marlborough tree brooms, Carmichaelia muritai and C. stevensonii, both of which rank among the most spectacular members of our native flora when in flower (as shown above). Of the tree daisies, Olearia coriacea and O. nummularifolia var. cymbifolia stand out in particular; on account of their bright, somewhat conventional foliage, drought tolerance and tidy habits. Other plants of dryland habitats that feature strongly in the structure of the garden include the divaricate species, Corokia cotoneaster and Sophora prostrata.
Gravity heavily dictates the flow of water. For this reason, the lower parts of the garden are occupied by species that prefer a certain degree of moisture to perform well; especially plants that occur in the slightly wetter climate at the foot of the Alps. In addition to the effect of gravity, this part of the garden retains more moisture due to the greater concentration of stones that we placed at the foot of the slope. Plant roots find both moisture and shade on the underground surface of rocks, especially in a summer climate as harsh as that of the Mackenzie Basin.
Prominent within this zone is the bright green foliage of Hebe subalpina, in association with the dark-stemmed mountain wineberry (Aristotelia fruticosa) and the blue-grey mountain toatoa (Phyllocladus alpinus); shrubs that feature heavily within subalpine scrub communities in Aoraki/Mt Cook National Park. On the fringes of this planting is the nationally threatened climbing broom, Carmichaelia kirkii; a species that we were keen to plant in good numbers, as a local population of it had been destroyed (within relatively recent history) by the raising of Lake Pukaki.
It is interesting to note that this and other species of brooms are, reportedly, particular susceptible to browsing by rabbits; yet within the garden at Tekapo, none of the brooms have shown any discernible signs of this sort of damage. It is possible that this is largely due to the semi-regular application of an animal repellent spray to the planting during its establishment period.
As mentioned at the beginning of this profile, the garden contains various exotic flowering species that are integrated into the native framework. Several of these are as exciting as the southern natives that we were able to utilise within the garden, as they are plants that one cannot cultivate in the warmer climes of the north of New Zealand. Many northern gardeners can only dream of being able to grow foxtail lilies, paeonies or ornamental onions, and so the chance to be able to include such horticultural wonders within the design was an opportunity too good to miss.