Irrigation
Grafted verticordias should be planted into moist soil and watered regularly during establishment using drippers, particularly on sandy soils.
In summer, watering may need to be split into two to three applications per day depending on evaporation replacement required. This usually requires an automatic watering system. Once established, grafted verticordias are low water users (50% evaporation replacement or 4 litres per day per plant in summer in the Perth region).
Fertilisers
At planting, 10g of low phosphorus slow release fertiliser such as ‘for native plants' should be spread on the soil surface (not in the planting hole) adjacent to the plants.
Once established, plants (at two to three months) require a regular feed, preferably through the irrigation lines such that plants receive 150kg/ha of nitrogen, 115kg/ha potassium and 7kg/ha of phosphorus and calcium together with a balance of trace elements each year.
Injecting fertilisers during watering (fertigation) is an efficient way to meet the nutrition requirements of plants. This can be achieved by making up a stock solution of fertilisers in a 200 litre drum of water for pressure injection (see Table 1 for stock solution rates).
In summer fertigate plants daily. The concentration of fertilisers injected (particularly nitrogen) should be scaled back during autumn.
In winter fertigate every third day then increase frequency through spring. During each watering allow the irrigation system to run for 10 minutes without fertiliser. Then inject 10 litres of the stock solution per 800 plants being watered over the next 40 minutes, followed by 5 to 10 minutes of watering without fertiliser.
Acclimatise young plants to the fertiliser program by starting at the low rate (Table 1) and gradually increasing the frequency of injection over the first year and then increasing the rate in the second year until irrigated daily.
| Fertiliser product | Low rate (kg) | High rate (kg) |
|---|---|---|
| Urea | 2.9 | 8.7 |
| Potassium nitrate | 3.4 | 10.2 |
| MAP (mono-ammonium phosphate) | 0.4 | 1.1 |
| Calcium nitrate | 0.3 | 0.8 |
| Trace elements (Fetrilon Combi®) | 0.1 | 0.2 |
Pruning
Plants should be lightly pruned in the first year to encourage branching. Thereafter they should be pruned to about one-third of their height, as this will encourage long stem production. It may be necessary to allow plants to grow for two years to produce sufficient stem length.
Pests and diseases
Plants are susceptible to botrytis and mildew, particularly in moist weather during early autumn, which can cause leaf drop. They are also attacked by a range of insects including thrips, nitatulid beetles, weevils, caterpillars and scale.
Plants may need regular spraying with a registered fungicide to control diseases. Monitoring and field control of insects is essential coupled with an effective postharvest treatment, such as insecticide and fungicide dips, to provide sufficient level of kill to meet overseas quarantine inspections.
Postharvest management
Flowers can be a handled as for waxflower. Flowers should be cooled at 1°C to 5°C as soon as possible after harvest and will benefit from forced-air cooling after picking to remove field heat. Lengthy delays in removing field heat can seriously affect flower quality.
Flowers have a low ethylene flower drop response, although pulsing with silver thiosulphate may lengthen vase life. Alternatively, placing 1-MCP sachets (EthylBloc®) in flower boxes may be effective at controlling ethylene response.
Further reading
https://rirdc.infoservices.com.au/items/12-110
Acknowledgements
The support, cooperation and assistance of the Australian wildflower industry is gratefully appreciated.
Funding support from the Rural Industries Research and Development Corporation and the Department of Agriculture and Food is acknowledged.