In the “Protecting and restoring our natural heritage - a practical guide”
Before you can start planting, some important tasks should be tackled. Good site preparation will make planting easier and increase the success of your project. If your site is well prepared, weed competition for light, soil moisture and nutrients should be minimal, and digging the planting holes should be easier.
Fencing is usually essential to prevent grazing damage to plantings, but gates can allow unwanted access and rabbits can sometimes get underneath. You can seek fencing advice from DOC, local authorities, groups involved in other restoration projects and fencing contractors.
For managed grazing, you will need fencing to control the level and frequency of grazing. If rabbits are a problem, rabbit netting can provide effective long-term control, but it is expensive and needs regular checking. The base must be well buried and secured with rocks or logs, or extended out as a 30-cm apron, secured by wire pins.
- Fence the site to exclude grazing animals.
- Install rabbit netting where rabbits are a major problem.
- Locate fences to provide buffering around the restoration area where possible.
- Keep fences as straight and short as possible – cheaper and more effective.
- Use stiles for access across fences, not gates.
Weed and pest control
Friable soil makes planting easier and encourages root development. Normally, all you need to do is cultivate each planting patch with a trenching spade or crowbar. Mechanical ripping may be needed in mined areas, dry stony areas, artificially compacted sites, and sometimes clay soils. Do the work with a bulldozer or tractor with a winged ripper, when the soil is neither too wet nor dry. Clay soils are normally best ripped in late spring/early summer, while stony soils can normally be ripped at any time (R Simcock, pers.comm). If you are unsure about ripping, seek specialist advice.
For artificial or degraded soils, lime and fertiliser may be required. Only import topsoil or organic material if the existing substrate is very stony or rocky, or is composed of unconsolidated waste. With the latter, you may need to add up to 1.5 m of topsoil (Ross, Simcock and Gregg 1998). Be cautious when importing topsoil because you risk introducing foreign seeds and microbes.
- Loosen soil to a depth of around 0.5 m if possible (Meurk, Lucas Associates and Christchurch City Council (undated)).
- Add topsoil, organic material or fertiliser only if the original topsoil has been lost or degraded.
You should remove all existing vegetation from the planting patches by spot-spraying or screefing (skimming off surface vegetation with a spade or grubber), to reduce competition for water and light. Grasses especially can overwhelm plantings. Avoid over-clearance as weeds will re-invade any disturbed ground (Porteous 1993). If you cannot plant the cleared patches promptly, they can be mulched and spot sprayed at planting. Alternatively, they can be left to allow other weed seeds to germinate before final spraying and planting (Porteous 1993). Mulching the cleared ground will reduce weed invasion and conserve soil moisture.
- Clear a 1-m patch for each plant (Meurk, Lucas Associates and Christchurch City Council (undated)).
- Do not over-clear surrounding vegetation.
- Do not damage other plant roots, or remove too much topsoil.
- Mulch exposed ground with the removed vegetation.
- Plant promptly (within a week, preferably sooner).
Always minimise the use of herbicides – some people have valid concerns about the use of toxic substances. Careless spraying can easily kill native plants (Fig. 2 shows the correct spray pattern to use).
Figure 2 - spray patterns
Using other methods as much as possible can reduce or confine herbicide use. For example, cutting and stump poisoning allows precise weed removal with minimal damage to other plants. Once vegetation has been cleared for planting, you should use mulching as your main method of weed control (see section 9, Mulching for details).
If you must use herbicides:
- Follow manufacturer’s recommendations carefully.
- Follow recommended safety precautions to avoid harming people or contaminating waterways.
- Spray only in calm conditions.
- Use a wetting agent to improve adherence and results.
- Protect non-target plants by shielding them with cardboard, plastic board or plastic bags with the bottom cut out (Porteous 1993).
Table 6 summarises the main herbicides available for use at pre-planting and release times. Table 7 lists major agricultural suppliers of herbicides, repellents, and fertiliser. For more information on the range of chemicals available, safety procedures and spray equipment, consult the NZ Agrichemical Manual, available from horticultural suppliers and some booksellers.
Table 6. Common herbicides used to control weeds
(View table 6)
Herbicides can be dangerous!
Before you purchase herbicide, carefully read the label or the Material safety data sheet - MSDS (available from suppliers) to answer the following questions:
- Is it the right product for the job?
- Are there restrictions on its use?
- Can the product be used safely under your conditions?
- What environmental precautions are needed?
- Do you have the right equipment to apply it?
Before you apply herbicide, read the label to answer the following questions:
- What protective clothing is needed?
- How much to use?
- How and when to apply it?
- What can or cannot it be mixed with?
- What is the withholding period?
- What warnings, precautions and first aid measures need noting?
|Agri chemicals/fencing/pest control baits and bait station suppliers/tools/sprayers:
Pyne Gould Guinness (03) 343 3999 Greenfield (03) 365 0677
|Wholesalers of pest control: traps, baits and bait stations:
Trappers Cyanide (03) 359 4150 Pest Management Services (0800) 111 446 Feral Control (09) 433 3273
Nufield Marketing (Plantskydd) (03) 348 0799 IWT Ltd, Chch (Plant Plus) 0274 329 110 Kiwi Care (Thiro-protect) (03) 398 0778 Aorangi Forestry Services (Treepel) (03) 689 7993 Southern Woods Nursery (Liquid shotgun) (03) 347 9221 Elliot Chemicals (X-Pel) (09) 521 1562
|Windbreak/weedmat (bulk suppliers):
Donaghys Industries Ltd. (0800) 942 006 Cosio Plastics (025) 335 704 (weed stop/wire, pins/plastic pins). Permethane (09) 828 5179
|Bulk suppliers of windbreak cloth/weedmat/fertilisers
/weed killers/irrigation materials:
Carann (wholesale) (03) 359 7914 Egmont Seed Company (wholesale) (03) 349 5546 Fuitfed (03) 349 9948 Hortlink (03) 348 8220 Yates N.Z. (wholesale) (03) 349 9223
|Woolmulch Biomac (erosion and weed control matting):
Maccafferi NZ Ltd (distributors) (03) 349 5600
|Fencing and fencing contractors - Refer to Yellow Pages.||Home garden suppliers of windbreak cloth/weedmat/fertilisers|
/weed killers/irrigation tools:
Mitre 10 Smiths City Placemakers Other hardware stores
See 'Irrigation Equipment and Services' in the Yellow Pages.
See 'Garden Supplies' in the Yellow Pages.
Disclaimer - this table lists suppliers, which at the time of publishing this guidebook were known sources of these products or services. They are not necessarily endorsed or recommended by the Department of Conservation. If you wish to update this list please contact the Department of Conservation Nursery at Motukarara +64 3 329 7846.
Providing temporary shelter
Providing shelter for planted natives is particularly important in difficult or exposed sites. Your options range from retaining shrub weeds as nurse plants, to planting shelter, to using shade or wind cloth for small areas.
Retaining shrub weeds
Consider retaining woody weeds as nurse plants to provide shelter for planted natives, e.g., crack willow along riparian areas, gorse, broom, elderberry, tree lupin and tree lucerne. Unnecessary removal of trees and shrubs is expensive, it may create new weed problems and eliminate valuable shelter, and tree removal may upset local people. For detailed information on using existing gorse and broom as nurse plants, see section 4, Managing succession through shrub weeds.
Thinning, line-cutting and planting
A hybrid approach that accelerates natural succession could be helpful (use Table 3. Factors affecting succession through gorse and broom as a guide to when this is appropriate). This requires thinning or line cutting, depending on the age and openness of the shrub weeds. Native plants established in the cleared spaces will eventually form a canopy over the shrub weeds and suppress them.
Planting the boundaries densely, with only scattered planting (5-10 m spacings) in the interior, is an option. The boundaries will need intensive management until native trees are established (say 2-3 m tall), after which native dominance will be achieved with minimal maintenance. Similarly, planting into patchy gorse and leaving it for 3-5 years will result in some gap-filling by shrub weeds, but they will eventually be suppressed.
Broadleaved trees planted along cleared edges of gorse reduce gorse regeneration and provide a seed source that will accelerate the succession of native species under the maturing gorse.
Do not over-thin or clear. This may create more problems than it solves by letting in light and allowing suppressed weed seedbanks to spring into life. The Christchurch City Council has trialled the shredding of several hill blocks of shrub weeds with a mechanical chipper, in preparation for planting through the slash to hasten natural succession. Their approach was in response to pressure from residents over the weeds and fire risk, and finance was available at the time. Invading grasses were sprayed and the planted natives were mulched with paper discs. After two years, the slash had largely disappeared and shrub weeds had re-established from the seedbank. While this approach has allowed easy access for planting and maintenance, increased weed control will be needed until a native canopy establishes.
Where you have broom or gorse at or near the treeline, an untested option would be to inter-plant local native species, e.g., mānuka, dracophyllums, olearias, hebes and cassinia/tauhinu (see section 4, Managing succession through shrub weeds). Their growth will be slow, like that of the shrub weeds at this altitude.
Planted and artificial shelter
On some sites you may need to plant nurse species to provide shelter. Always attempt to establish a native canopy for sheltering other native plants. Sometimes you could consider planting temporary fast-growing exotic species (e.g., tree lucerne in dry sites), but this should be a last option. Tree lucerne can spread beyond the site if adjacent land is not grazed.
If the site is exposed, windbreak or shade cloth can provide shelter and quick results, but this is practical only for small areas. Planting borders of dense, shrubby species adapted to the conditions should limit the need for this approach.