FERTILISERS

Why fertilise?
All plants,both native and exotic, need three essential elements in balanced proportions in order to grow. These are nitrogen, phosphorus and potassium. In the field theseare provided by the continuous decomposition of leaf litter and animal droppings.

The type of growth we typically see in the Australian bush is much less than optimal for the plants, hence the general consensus that Australian plants are 'straggly and unattractive'.Whilst it is true they need less care and less fertilising than imported plant species, in the garden we can ensure our native plants reach their maximum beauty by the sensible use of fertilisers.

When should we fertilise?
Spring is a good time to fertilise your plants, on the East Coast, August - September. A second application can be made in February

How do we apply fertiliser?
Water the garden well first. Most native plants tend to send roots out horizontally in a similar manner to their above ground spread. This is an adaptation which ensures that the plant makes the most of any rainfall. Spread the fertiliser around the root zone taking care not to apply more than that recommended on the label. Rake the fertiliser into the soil and then water the area again.

What fertilisers can we use?
Some native plants, particularly those in the family Proteacea (Banksia, Grevillea) do not tolerate high levels of phosphorus so you need to be careful what fertiliser you apply. There are a number of off-shelf products specially formulated for use with native plants. The best general mix of elements in such fertilisers is Nitrogen 10%, Phosphorus 4% and Potassium 6-7%.

Fertilisers can be divided into inorganic and organic fertilisers. The former are composed of mineral salts, carefully formulated and with the appropriate labelling. Some of these (slow release fertilisers) are made into pellets the covering of which breaks down over time. Organic fertilisers, on the other hand, are made up from manures, mulches and other forms of compost. These are less specific in composition are more economical and can be used in less precise quantities.

Power Pellets: An excellent and inexpensive product, these come in bags of up to 20kg in weight. The pellets are organic and have a pleasant aroma. The effect lasts for between 8 and 10 weeks and provides lush growth as well as improving the soil.

Blood & Bone: This is a good organic fertiliser, generally available packaged and with instructions for use. Do not spread it too close to the stems of your plants and use sparingly because some brands are enhanced with inorganic compounds which may be a little high in phosphorus.

Charlie CARP: This is a liquid organic fertiliser made from carp (fish). It is used to give plants a boost after pruning or to re-vitalise plants that need a lift. It is also useful in planting out your new plants. Care should be taken to ensure that you use the correct dilution with your natives. It can be used most beneficially with native orchids as they bud up.

Poultry, Cow and Horse manures: All these are good organic fertilisers but need to age before use with native plants. They do need to be used with caution around plants in the family Proteacea as they are quite strong and often high in phosphorus.

Osmocote: A slow-release fertiliser which is excellent for use when planting out or with potted plants. Be sure to purchase a product formulated for native plants. Odourless and clean, the chemicals are released over a period of about 6 months. It is best mixed with some soil at the bottom of the hole into which the plant is to be placed so it is available to the roots as they grow.

Nitrosol: A liquid fertiliser which has a formulation for natives. Easy to apply diluted using a watering can.

>> Visit Sydney Wildflower Nursery Heathcote for fertilisers and advice on the most suitable for your particular purchases <<

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