Growing native plants in your home garden? |
Native plants
New Zealand’s geographical isolation from other land masses for the last 80 million years has meant that our native plants have evolved in isolation from other vegetation, producing unique forms. Most of our native fauna (80%) is endemic, i.e. only found in New Zealand. However, the arrival of people about 1000 years ago had a dramatic effect on native forests, birds and freshwater wetlands, reducing their biodiversity considerably. This decline in biodiversity is of great concern to those who place a high value on our native flora. Further decline can be prevented by promoting the growth of native plants in the natural environment as well as garden settings.
Growing native plants in your home garden?
- Buy native plants from the nursery because they have been selected for their good form and have been well established for the garden setting.
- Purchase plants that suit the environmental conditions in your area.
- Consider the size of your garden and how much time you are willing to spend on taking care of your plants because the time required varies with different types of plants.
- Give your plants good soil, nutrients, water and shade, as required.
| Natives in soil | Water or soak the root ball thoroughly before planting. Dig a hole twice as big as the root ball to give the root system enough space to grow in and establish quickly. Add compost, organic matter, slow release fertiliser, or blood and bone and then mix. Remove the cover or container surrounding the root ball and loosen the root ball gently with your fingers to release the roots. Stretch out the old roots so that they are able to reach the soil mixture. This will encourage new root growth. Then place the root ball inside the hole and cover it with firm soil up to or slightly above the surface of the ground. If planted too deep, the plant will eventually die from pests and/or disease. Water well and cover the root zone with about 5 cm of mulch (e.g. compost or organic matter) to help keep the roots cool and the soil moist. |
| Plant care | Water the plants, i.e. water as required to promote root elongation. Regular fertiliser and pruning are generally not necessary, but a slow release fertiliser or blood and bone can be applied and plants pruned in early spring and summer |
| Natives in pots | Select a pot that is twice as big as the root ball of the plant and has drainage holes in its base. Soak or water the root ball thoroughly. Cover the drainage holes at the base of your pot with stones or a piece of broken pot to allow drainage and prevent your plant from drowning when you water it. Cover the base of the pot with commercial soil mix that contains slow release fertilisers. Loosen the root ball with your hands and place the root ball inside the pot. Cover it with firm soil to avoid the build-up of air pockets that will interfere with the movement of water and air inside the pot. Water well. If possible, raise pots above the ground, exposing the drainage holes to ensure good drainage and avoid leaving your potted plants in water-filled saucers otherwise plant roots may suffocate |
| Plant care | Water frequently and feed using a slow release fertiliser or with blood and bone, twice a year, preferably in late winter and again in mid summer. Prune if required in early spring and summer |
As environmentally aware gardeners, never collect native plants from the wild and grow them in the garden. Firstly, plants taken from the wild often make the worst possible garden material because the conditions in which they have been growing are often difficult to duplicate in the home garden. Plants from the wild also tend to suffer from transplanting shock, and are often not the best specimens. Seed collected from plants in the wild is also highly variable, again often producing poor specimens. Finally, such collecting is potentially detrimental to the location they were obtained from, if not illegal.
- Native spinach, northern (Tetragonia tetraganoides) and southern (Tetragonia trigyna) – the only native plant sold as a vegetable
- Cabbage tree – has edible crowns
- Snowberries and Coprosma – has edible fruit
- Climbing kiekie – has edible flowering bracts
- Manuka, kamahi and rata – are used for honey production.
Pests and diseases of native plants
Not many native plants are prone to pests and diseases, unlike many cultivated plants. However, they are prone to certain diseases, but most of these are general such as damping-off fungi and the occasional rust. Few diseases require special sprays, but a selection of those that do are described below.
| Manuka blight | Kowhai moth caterpiller |
| Health manuka plant (pic) | Kowhai moth caterpillar (pic) (www.landcareresearch.co.nz) |
| Kills off many of the young attractively flowered cultivars of manuka (Leptospermum scoparium), while kanuka (Leptospermum ericoides) is only mildly affected. Manuka blight is caused by a scale insect (Eriococcus orariensis) that feeds on the sap. The black smut lives on its excretions (i.e. excess sap named `honeydew’) and a soot fungus, Capnodium walteri, feeds on the smut, blackening the excretions and reducing the photosynthetic capacity of the plant. The plant dies from the excessive extraction of sap caused by adult female and nymph scale insects. | The caterpillar of the native moth, Uresiphita polygonalis maorialis, which is present throughout New Zealand, feeds on the leaves of kowhai (Sophora), yellow tree lupin (Uresiphita polygonalis) and occasionally gorse, clover and broom. |
| Control: This insect was accidentally introduced from Australia so no parasites or predators exist in New Zealand to control it. However, a parasitic fungi (Myriangium thwaitesii) of E. orarienses kills the insect by penetrating it with its hyphae (the vegetative structure of many fungi). Spraying with summer oil or maldison combined with a spreading agent can reduce the effect of the insect on your ornamental manukas (www.forestresearch.co.nz). |
Control: Kowhai tends to recover from even the most severe attacks. Nevertheless, any insecticide designed for chewing insect will help control the problem. |
