Horticulture - Fertilising

Standard fertilisers have around 10% Nitrogen, 4% Phosphorous and 6 – 7% Potassium. Most native plants respond well to these levels of nutrients.

Some families of native plants (for example, Proteaceae, Fabaceae) cannot cope with Phosphorus, so native plant fertiliser with very low or no Phosphorus is used for these plants.

Each plant in a pot at the nursery receives a measured amount of controlled release fertiliser when they are potted up or re-potted. Each year the permanent pots are re-potted and the plants have controlled release fertiliser added to the potting mix.

New plants planted in the grounds of the Gardens have a slow release fertiliser applied to their root zone, followed by a thorough watering. Most plants do not receive any additional fertiliser, unless they are in poor condition or appear nutrient deficient.

Plants grown in altered sandy media can become nutrient deficient, so do require fertilising. For instance, the Rock Gardens are fertilised twice a year with slow release fertiliser and a supplement of liquid fertiliser is applied every four weeks during the growing season. This could be a seaweed solution, or a liquid fertiliser high in Potassium.

The rainforest plants are self-sustaining, drawing nutrients from the thick layer of organic material that lies on the floor of the forest or is trapped in epiphytes.

The plants grown in the Glasshouses – the orchids, ferns, palms and ant plants – have dilute liquid fertiliser applied fortnightly in summer. In winter, the application is monthly or less often.