A major factor influencing the success of a native plant nursery is the way water is managed during the production of plants. Water is important in many ways, and the following brief guide may be of assistance.
- Water quality is critical. Growers in regional or rural Australia may rely on dams, bores, rivers etc for their supply. It is essential that the water be chlorinated or otherwise treated to ensure that no water borne pathogens are transferred to nursery stock. The water should also be checked for salinity if it comes from springs or bores. Recycled nursery water will also have a higher salt content than when it was first used in the nursery. As a rough guide an E.C. of 900 is usually acceptable for most plants. Some species or cultivars can withstand much higher levels without damage.
- If the supply water is highly coloured from a dam or waterway, it can be clarified by pumping it through Aluminium sulphate (Alum) to drop out the clay particles. An old 200 litre plastic drum with an access hatch cut into it for adding Alum, and an inlet fitting from your water source and an out let fitting to your supply dam works well. Alum will increase the acidity of your water, and if your pH falls below 6 you may have to add some lime, depending on the range of species you grow. If your water is alkaline, iron will become unavailable to plants when the pH exceeds 7.5. There are several excellent publications available on the management of nursery water pH.
- Effective drainage of irrigation water away from your pots is essential. Water that remains in areas where plants are standing is a major disease risk, and will quickly spread infection through the nursery. Most growers use 20 mm diameter aggregate at a depth of at least 50mm to ensure that the base of the pot does not sit in water. There are also mats which will keep the plants out of the used water. Some nurseries grow their plants on raised benches to eliminate contact with drainage water. This also saves labour in plant management by eliminating bending over.