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 |  | Header image: NZ crab spider (look carefully) well camouflaged on an Olearia cymbifolia. Species unknown, spider experts please get in touch! |
| News from the nursery and summer outlook |
| Following a wet and average temperature, though late-starting, spring season we’ve had a relatively rainy and cool start to summer. The forecast suggests with medium confidence that we’ll be seeing average or above average temperatures and normal rainfalls and river flows.
The NIWA drought forecasting tool suggests the next 35 days have no chance of a drought, with very dry conditions only occurring in Otago and Southland in a 90th percentile scenario.
The cool start to spring delayed foliar growth, but the summer conditions have made up for it so far, so we have a lot of things coming ready for summer and autumn that missed the mark this spring.
The late spring has led on to a delayed fruiting and flowering season, with fruit ripening at the nursery looking 3 or even 4 weeks later than usual. A hot summer can help to rebound flowers and fruits after a late spring, but this cooler, wetter summer so far has been good for foliar growth but hasn’t stimulated fruiting. |
|  | Above: Professional alpaca shearers making quick work of our woolly friends at the nursery |
| We’re continuing our potting program, this week doing a number of larger grades, and we’re introducing a number of new lines for the future. Our propagation program continues to increase in size and diversity. |
|  | | Optimise planting with Olearia |
| There’s no place quite like Central Otago - it is a climate of extremes. The temperature can swing twenty degrees in a day, a warm day followed by snow, spring rains followed months of drought. This extreme climate has been the norm for thousands of years, since the last ice age, with humans having only experienced this area for a short portion of time. However, plants and animals have been here in the forms we see today for thousands of years. These plants have adapted to the climate, the environment and each other to survive the test of time. When choosing species to plant into this environment it makes sense to use the plants with the most genetic adaptations to the area.
Most of the areas that are developed for housing are in the flat basins between the mountains. It is widely circulated that the main plant species/habitat in Central Otago before human settlement was mountain beech forest. Whilst it is true that forest would have covered most of the mountains up to the tree line, it can be argued that it would not have been dominant in the basins. Basin geography and climate is different to mountain sides and thus so is the ecology. Basins can see higher rates of disturbance via flooding as they usually have substantial rivers running though, they can also have harder frosts. Our basins tend to have higher accumulations of rock from glaciers, and while this makes for mineral rich substrate it can be very free draining. Due to the mostly flat topography of a basin they will get more sun than mountain sides and heat up rapidly, especially with no wind. When the wind comes the surrounding mountains can funnel it through desiccating anything in its path.
Over thousands of years plants and animals together changed and adapted to these conditions, resulting in a diverse basin ecology filled with different sizes of shrubs and smaller trees. It is imagined that these plants created a network of open shrubland. From the fossils found in these areas and from particular plant adaptations it is thought that the basins would have been a favoured habitat for several species of moa. It is unfortunate that this has to be imagined because as far as we know this ecology no longer exists due to past human actions. However the plants still remain in pockets testifying to their greater presence in the past.
It is a common belief that planting native plants will have less deaths and more success than planting non natives. Yet this is only true if the correct native plants are selected for the correct site and no special treatments (such as fertiliser and mulch) need to be given. Planting the correct natives in Central Otago/Lakes is more difficult than many other places in New Zealand as most of the natives grown in New Zealand are forest species unsuitable for basin environments. This makes sense as Central Otago/Lakes combined make up 1.5% of the population. Meaning the other 98.5% of the population influence planting trends and information for the gardeners here.
It is our mission to continue to piece together the puzzle of our pre-human intermontane basin ecology and make these plants accessible. It is our hope that one day the network of species we once had can once again become a tapestry woven through our human landscape. We are now beginning to have success in our propagation and production efforts to get top quality specimens of some of these plants in quantity. One species in particular that is woefully underappreciated and underrepresented in our gardens and amenity plantings are the tree daisies, Olearia. There are 35 species of native tree daisy in New Zealand distributed across the country. In Central Otago/Lakes we have 11 species - which occur naturally in the environment, but rarely in garden centres. We have all 11 species in production at the nursery. These tree daisies can either be very common or critically endangered. |
|  | Above: Olearia hectorii (left) and Olearia haastii PB6.5 growing well in the nursery |
| One of the most common that we see is the scented tree daisy, Olearia odorata. During summer Olearia odorata flavour the air with their soapy scented flowers. One whiff evokes a memory of tramping on hot summers days surrounded by dry hillsides and the buzzing of bees. The fragrance is designed to entice moths to visit and pollinate their flowers. Moths are important pollinators for many New Zealand species and Central Otago has more than its fair share of moth and butterfly species with over 1000 out of 1750 described species, 90% of which are only present in New Zealand. Most moth species studied are either threatened or at risk. Many of these species only live on Olearia and numbers have plummeted with the removal of Olearia trees. Moths make up a good portion of diet for bats, ruru, little owls, lizards and many birds making them a key link in the food chain. Without a good population of moths many of our more popular species will falter. Different species of Olearia will flower at different times in the year, so planting a selection of Olearia will provide nectar from late spring to mid autumn.
Olearia odorata is a medium bush growing to 4m high. Its small grey furry leaves are tailored to dry, windy and sunny situations, with it often found growing in a crevice on a steep hillside. It is very frost hard, growing in frosty flat valleys at high altitudes between beech forest. Olearia odorata would make a good small multi stemmed feature tree in a dry garden. It will effortlessly make up part of a mixed planting for screening or revegetation.
Olearia lineata is a slender shrub growing to 4m tall. It has needle-like grey leaves with dense slender upright branches which give an airy effect especially when swaying in a breeze. An earlier flowering Olearia, daisy flowers can be seen from late spring to mid summer. It is often found along river and creek edges but it is frequently found in very dry areas. So far we have found it to be relatively less palatable to browsing animals such as deer when established. Olearia ‘Dartonii’ is a cultivar of Olearia lineata as cultivars generally need to be propagated via cuttings; they won’t be as healthy as seed grown eco sourced Olearia lineata when faced with challenging dry conditions.
Olearia hectorii is a nationally endangered tree daisy with 4500 individuals reported across the south island; a good proportion of these are located in the Matukituki valley. However this population is old and unable to reproduce due to pasture grass stopping seed from germinating. Once these old trees die we could see these trees disappear from the landscape entirely. This would be a sad outcome as these old trees are magnificent. Their trunks are fissured and tactile making great habitat for all manner of bugs. The trunk is topped by almost lime green light foliage which is dropped in winter making it one of New Zealand's rare deciduous trees. It is the first species of Olearia to flower in Central Otago, with October flowers making it a welcome food source after a cold winter. Naturally Olearia hectorii grow in alluvial slips, found at the sides or base of a gully where slips create perfect conditions for the seeds to germinate. They grow to a maximum of 9.5m high and can have a 5m wide canopy. They prefer a site in full sun to part shade with good moisture but will tolerate some drought. With the threats Olearia hectorii face, every tree planted in gardens, sections and revegetation will be helping to secure the future of these beautiful trees. |
|  | Above: A glorious old Olearia hectorii in the Matukituki valley |
| Interestingly, phylogenetically Olearia are found among the Asteraceae, or daisies, one of the most common and visible plant families. Daisies are descended from (and most still are) small annual herbs, so the Olearia have evolved woodiness, or to put it another way, independently discovered being a tree. This is a property shared with a number of NZ native plants, the reasons for which we may explore in a later article. |
|  | Above: Tree of Life showing location of Olearia genus (yellow mark). Source: Lifemap NCBI |
| | The hills and mountain tops of Central Otago are characterized by a sea of tussocks billowing in the wind. The same effect can be captured at a smaller scale in our gardens and on berms. Most often this effect is recreated by using Red tussock, Chionochloa rubra, and when planted in the correct place the brown foliage of this tussock can look great. Red tussock has become ubiquitous in Queenstown with many gardeners told it is a hardy plant, local to the area and good for berms, unfortunately these are half truths. Chionochloa rubra is hardy when established but it takes a long time to get there and in between these plants can readily succumb to being too dry, too wet or too wet/cold. Rabbits love Chionochloa and will reduce a whole planting in one evening, which for a slow growing tussock like Chionochloa could take years to recover, if they ever do.
Some Chionochloa rubra may be found locally but they will be in gullies, seeps or tarns up the side of a mountain and not in huge numbers. They are more commonly found in wetter climates in the South Island, with farms in Southland hosting good populations. As previously stated red tussocks do not like to be too dry when young so it is difficult to establish a berm of red tussock even with irrigation as water flows off the berm. Red tussocks are also not the best plants for weed suppression as they need to be close to stop sunlight reaching the ground and as they are slow growing this can take five years or more to happen.
With this being said, there is a tussock that can do everything a red tussock can’t, the silver tussock, Poa cita. Poa cita is a fast growing evergreen tussock that will reach 80cm high and wide. It is very hardy to cold and drought, once established it never needs to be watered again. This is because it rapidly grows roots that go deep into the earth making it great for erosion control on berms and steep banks. For good coverage on a berm plant 50-70cm apart. So far we have had good success in difficult locations in Cromwell and Bannockburn without continued irrigation. It will also grow foliage rapidly getting to its full size in a few years. If planted close enough it will shade the ground reducing weeds and evaporation from the soil. The shedded foliage will start to build organic matter, often depleted in poor dry soils, eventually changing the soil into soil that can sustain larger shrubs. |
|  | | Poa cita is very common in the landscapes of Queenstown Lakes/Central Otago due to its vigorous nature - it can compete against introduced pasture grass species. We have also had success leaving these plants unguarded to rabbits as they can outgrow how much the rabbits can eat. This will depend on rabbit populations but guarding for the first year to get a good size before removing the guards works well. Rabbits prefer fresh growth of Poa cita which is produced mainly at the centre of the plant, and once the plant is larger this growth is difficult for a rabbit to get to. For our own plantings in dry areas we use Poa cita as a ground cover and plant our shrubs and trees in between. The larger plants will eventually shade them out but until then the Poa cita will provide shade to the roots and some protection to stems. It is a low maintenance plant that you can plant, forget about and let it do its thing. |
| | We’ve recently had a large batch of Prunus lusitanica PB18 come available, these are great value so if you need a hedge, get in quick! |
|  | Prunus lusitanica PB18 $23.00 Common/Maori name(s): Portuguese laurel Highly popular evergreen hedging plant or large tree if left to grow. Dark glossy leaves create a stately looking hedge. Hardy and tolerant of a range of growing conditions but grows best in moist, well drained soil. Height of grade at sale: 60cm |
| | As always if you are planning any plantings or big jobs for this autumn or next spring let us know and we will prepare a quote. The more lead time you can give us, the better we can meet your needs.
Check out our Catalogue for more information or feel free to flick us an email or a call.
As always, if you want a quick overview of what we have immediately available in stock, you can check our order page. |
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