Article for Indigena Magazine
My wife, Jenny, and I established Pukerau Nursery in February 1979 with the intention of growing and supplying the rural market with shelter and amenity trees. Natives were not exactly popular for shelter in Southland then. In fact, it would be fair to say, natives were rarely thought about in the context of shelter on farms. I distinctly remember a local farmer coming to me for Red Tussock to plant out in his hilly paddocks in broad sweeps so as to provide shelter for his flighty Perendale ewes and lambs so that he could leave them to it. Such enlightenment was unusual and encouraging.
It wasn’t long before my National Park upbringing, or was it a case of, “you can’t fight your genes”, meant we were also growing natives and encouraging their use for low shelter where appropriate. To ensure a year round income I also developed my interest in landscape design and started designing and planting gardens and shelter. For many years Jenny’s teaching kept food on the table. Over the years both the landscaping and nursery have developed to the point where now we employ a Landscape Architect, a contracting team and 5 fulltime and 5 seasonal persons in the nursery. Plants are supplied to the landscape market, councils, garden centres, rural and urban public for farm shelter, revegetation projects and for the landscaping of residential and commercial properties.
“Natives wont handle the frosts and exposure”, was the common cry of the time. “Bollocks” was my reply, “ it is a case of choosing the right plants for the right place and imitating natures patterns”. Easy- yeah well. Certainly there was experimenting to find out what worked better where but then that had already happened with the exotics that were predominantly used. Encouragement was given by regional council advisors and a few farmers who were already planting natives as part of their shelter system.
From the beginning I believed frost hardiness was paramount so we collected seed from the coldest places we could find. It also meant we did not buy in plants from ‘wussy’ climates. A lot of the new cultivars used in landscaping were just not tough enough. The winter of 1996 set a benchmark. The anticyclone, stalled over Southland after a decent snowfall, created a fairytale winter wonderland. The dry powder snow stayed on the fine Silver Birch branches for a week. Our minimum temperature was -15C and maximum -8C for a two week period. The cross-country skiing was fantastic and fences were declared hazards for kids on tobogans. Damage to trees was severe. Natives, Eucalypts and late trimmed hedges, in particular, were severely damaged. Any plants still with sap flowing became seed sources. Their genetics would ensure that a greater number would survive another similar event. Euc. nitens was killed in many shelterbelts. This was a blessing in disguise as E.nitens was swamping the Western Red Cedars they were planted with. These Cedars are now excellent shelter. Eucalyptus rodwayii (Swamp Peppermint Gum) withstood the freeze well in most places and is now used extensively since it handles wet and dry sites. Natives were hard to sell for a couple of years but once people realized that seed was coming from plants that survived sales picked up.
As a result I believe we have built up a reputation for cold hardy plants. We still continue to collect seed from the coldest areas but this in relation to the three main climatic zones of Southland – coastal, intermediate and inland. Also, where critical, seed is collected from as close to the planting site as possible. This is mostly for contract growing situations. In Southland the three climatic zones are not too dissimilar to the ecological zones so I feel that our system is fine for general shelter planting. Record keeping ensures that plants are matched with the zone they are going to be planted in. I guess we need to take into account way the seed is naturally distributed when deciding from where to collect. Some seed is distributed very close to its source but that which the Kereru eats, for example, can be very widely distributed. A study by DOC has shown that Kereru travel from Invercargill to Stewart Island and back, up to the Hokonuis and roundabout. I will never forget the sight and sound of 50-70 Kereru lifting off from Broadleaf in the Hokonuis. Their bush telegraph had obviously said, “The Broadleaf seed is on at Middle Ridge”. Heavens knows where that seedlot was spread. Seed collected is recorded, cleaned and appropriately treated before sowing.
Initially, shelter grades were grown in rootrainers and PB bags but when BCC Hiko trays arrived in the country we switched to the V150 side-slit and V310 trays which hold 24 and 15 plants respectively. The side-slit V150 has proven to be excellent for shelter and revegetation grades. The side-slits allow for air pruning along the side of the root plug. A comparison between the root structures of rootrainer and V150 grown plants showed that the resulting structure was better from plants grown in the V150side-slit. Another advantage is that the trays are reusable for years and easier to handle than rootrainers. Shrubby plants are topped to produce a good stem diameter and root: shoot ratio. Plants are 30-50cm high depending on the species. The potting mix is an even mix of peat and coal fines with dolomite, gypsum and control release fertilizer. The coal is used instead of coarse sand because it costs less but is also lighter making trays easier to handle for staff. An experiment showed a better growth rate with the coal. We are pleased with the plant we produce but are always looking for improvement. As in all nurseries consistency of product is difficult. PB grades of plants are grown for the landscape market mostly.
In an effort to conserve water and ensure that each plant received what water it required we developed a capillary mat watering system. Root pruning is achieved by painting the weedmat on which the trays are placed, with copper hydroxide carried in acrylic paint.
The V150 grade plant answers our customers wishes for a cost effective plant that is easy to handle on site, quick to plant and establishes well. With this grade of plant it is essential to have good weed control.
Planting techniques used in the south are probably not much different to elsewhere. Planting times are generally spring and autumn. In the spring we prefer to wait until mid September – October when the worst of the frosts are over, however, farming timetables often dictate otherwise. Many farmers have to have their trees planted by lambing – August/September, and with calving even earlier it means planting in June-July. Winter has only just got underway and newly planted seedlings can take a beating before spring growth starts. It is fine for deciduous Poplars and Willows but survival rates of natives and Eucalypts can be compromised by a spell of severe frosts. More farmers now engage the likes of ourselves to plant their trees while they concentrate on their stock. We prefer to pre-plant spray but often post-plant spray because there is so little calm weather in the spring. Early spraying means that the clover isn’t yet above ground and is dealt with in follow-up spraying. Gallant (selective to grasses only), Versatill (selective to Compositae and Legume families), Glysophate and Buster are the main chemicals we use depending on the weeds present and plants we are spraying around. Versatill will kill Kowhai and Olearia for example so care is needed. We do not usually use pre-emergent chemicals around natives. Plants will require at least one release spray later in the year.
We use a mix of pioneering species for low shelter either on its own or in conjunction with taller faster growing trees. With the later it is important to select plants that will cope with the competition from the taller tree. Flax, Toetoe, Kohuhu (Pittosporum tenuifolium), Olearia sp, Coprosma sp, Broadleaf (Griselinia littoralis), and Cabbage Tree are the basic choices with Wineberry (Aristotelia serrata), Manuka, Kanuka, Koromiko (Hebe salicifolia) Mountain Fivefinger (Pseudopanax colensoi var ternatus) and others used for variation. Plagianthus regius and Hoheria angustifolia are ideal for adding a bit of extra height especially in riparian areas. Environment Southland is encouraging dairy farmers to fence off waterways so many are using the opportunity to create shelter as well as trapping runoff and enhancing water quality.
In exposed coastal areas it is a good idea to plant flax first then a couple of years later follow in their lee with other coastal species. This technique has worked well at Southland Forest and Bird’s Te Rere Yellow Eyed Penguin Reserve. Establishment of the shrubby species is so much faster. Planting is at 1–1.5m centres, the thick grass sward is screefed, and control release fertilizer added (10gm per V150 grade plant). The shrub is planted with our Combo Tree Protector - a plastic spray guard, a net sleeve rabbit/hare protector then a mulch mat is placed around the plant and spaded into the ground to hold it. The mulch mat controls grass when spraying is maybe once a year as is often the case on volunteer restoration sites.
At another restoration site we have been involved from the beginning is an old coalmine site near Kaitangata (Balclutha). This 50 ha site has two distinctive areas. Thirty hectares is hillside that was covered in gorse and 12ha is highly errodable quartz gravel mining overburden. Any sane person would’ve run a mile. Rather than wait for nature to take its course the client, Solid Energy, wished to see native vegetation established quickly. The gorse was root-raked and windrowed by a hi-mack digger. The resulting gorse seedling germination was sprayed by helicopter and planting started. All plants were V150 grade with 20gm of Agroblen control release fertilizer. Woolmulch mats were used to control the next germination of gorse and other weeds. The mats are only 50cm square so pre-emergent Turb 500 was sprayed outside the mats, around the plants. The use of the mat ensured that the plant roots were not threatened by the Terbuthylazine and follow up spraying with Glysophate was easier for the operator. How did it work? The planting went well with a 96% survival in the first growing season but losses appeared in the very dry second year requiring some blanking in places. Gorse regrowth has been controlled by spraying and scrub cutting. The woolmulch mats were effective and certainly made spraying easier. The woolmulch mats are produced from waste wool- a joy to the ear of the farmer. They have lasted 2-3 years. After three growing seasons plant heights range between 1m and 3m. On the overburden a soil/compost mix was worked into the top 200mm to provide some organic material. The same fertilizer treatment was applied but mulch mats were not needed for gorse seedling control. Growth has obviously been a lot slower. Plants are being refertilized each year and probably will need to be until a litter layer starts to form. The plant mix is Toetoe, Kohuhu, Lemonwood, Manuka, Broadleaf, Koromiko, Wineberry and Cabbage Tree. Toetoe have done very well, next best are Kohuhu,Broadleaf and Koromiko. Wineberry and Manuka have not established easily. It is interesting that self seeding Manuka is establishing well. I have trialled Coriaria sarmentosa where organic material was not spread and it is establishing well and more is to be planted. To date 100,000 plants have been used. Everyone concerned is pleased with the result so far. Solid Energy is to be commended for their ongoing commitment to this project.
Queenstown developers are flat out trying to get their projects through the consents process. One requirement for some of the larger projects is native revegetation. This has presented us with an opportunity to grow under contract. Some developers expect vast numbers of eco-sourced plants to be available instantly but fortunately others are advised of the need to plan ahead and we have time to grow their requirements. The plant mix is interesting as the sites vary from Beech forest to grey shrubland to wetland. My farming friends at Fire Brigade are gobsmacked that anyone would want to plant Matagouri but the final straw was being told that we had to grow Cutty grass for one project.
I have become interested in threatened plants and we are collecting seed of Olearia hectori, O. fragrantissima, O. lineata, Coprosma wallii, Pittosporum obcordatum, Melicytus flexuosus and others.
Plants are returned to bulk up around existing old trees and when we have sufficient numbers we use them in other suitable sites To increase their range. It is always a great thrill to see seed germinating but more so with these threatened plants. The next best thing is seeing young plants growing on farms in habitats that are being restored. A plug for one plant- Olearia fragrantissima. How could anyone resist a plant of this in flower. The fragrance of peaches, apricots, gooseberries is arresting. I have just returned from another ‘sniffing’ outing in the Hokonuis.
Where to from here? I see the demand for native plants increasing although if some so called landscapers with a one plant vocab (Poa cita) don’t learn to use plants properly the demand may not last. In the Queenstown Lakes District Silver Tussock has been planted ad nauseum (it is cheap and fast) and it is putting some people off the use of tussock. Maybe some minimalist designers are such because their plant knowledge is minimalist. I think natives will continue to be part of the plant palette used in gardens because of the interesting foliages and textures and they give us a sense of place, a sense of belonging. The revegetation/restoration demand is set to continue for sometime. No doubt there will be some failures but as long as the commitment and maintenance is there, there will be successes as well. Grow well little trees.
By Arne Cleland.