How to Balance pH for Leucospermum Plants

Balancing the pH for Leucospermum plants is crucial for their optimal growth and health. These plants thrive in acidic soils with a pH range of 4.5 to 6.0. By following the steps outlined in this comprehensive guide, you can ensure your Leucospermum plants receive the ideal soil conditions they require.

Soil Testing

The first step in balancing the pH for Leucospermum plants is to test the soil’s pH using a home test kit. This will help you determine if the soil is too acidic, neutral, or alkaline. If the soil is highly acidic, you can add Calcium Carbonate, commonly known as garden lime or agricultural lime, to raise the pH. Conversely, if the soil is neutral or alkaline, you can incorporate elemental sulfur to lower the pH. However, it’s important to note that adjusting the pH with sulfur is not a permanent solution, as the pH may drift back to neutral or alkaline over time.

Amending Soil

leucospermumImage source: Pixabay

Once you have determined the soil’s pH, you can take steps to amend the soil and improve its overall quality for Leucospermum plants. If your soil tends to get waterlogged, incorporate woodchip mulch to help improve the drainage. If the soil cracks when it dries out and takes a long time to rewet, add gypsum to help break up the clay.

Planting Location

When choosing a planting location for your Leucospermum plants, it’s essential to avoid areas where water can pool, such as near downpipes and drains. Additionally, it’s best to plant them away from well-established trees, as these will compete with your new plants for water.

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Planting Time

leucospermum 2Image source: Pixabay

The optimal time to plant Leucospermum is in the autumn, as this allows the plants to become established in the garden before the heat of summer. If you can’t plant your Leucospermum until later in the spring, they will require additional watering to help them get established.

Reusing Old Flower Beds

If you plan to plant your Leucospermum in an old flower bed, it’s crucial to ensure that no phosphorus fertilizer has been previously used. Proteas, including Leucospermum, are best grown away from plants that require regular feeding. Avoid using mushroom composts, as they contain salts that can be harmful to Proteas. It’s also best to avoid applying blood and bone, manures, and products made from them, such as dynamic lifter, as the nutrient balance is not suitable for Proteas.

Balancing pH with Amendments

To balance the pH for Leucospermum plants, you can use the following amendments:

Lowering pH (Acidifying)

  • Elemental sulfur: Apply at a rate of 1-2 lbs per 100 square feet to lower the pH.
  • Aluminum sulfate: Apply at a rate of 1-2 lbs per 100 square feet to lower the pH.
  • Peat moss: Incorporate peat moss into the soil to increase acidity.

Raising pH (Alkalizing)

  • Calcium carbonate (lime): Apply at a rate of 2-4 lbs per 100 square feet to raise the pH.
  • Dolomitic lime: Apply at a rate of 2-4 lbs per 100 square feet to raise the pH and provide calcium and magnesium.

It’s important to follow the specific instructions on the product packaging and retest the soil after a few weeks to ensure the desired pH has been achieved. Adjusting the pH may require multiple applications over time.

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Ongoing Maintenance

To maintain the ideal pH for your Leucospermum plants, you may need to reapply amendments periodically, especially if the soil tends to drift back towards a neutral or alkaline state. Monitor the plants’ growth and perform regular soil tests to ensure the pH remains within the optimal range of 4.5 to 6.0.

By following these steps, you can successfully balance the pH for your Leucospermum plants, providing them with the ideal soil conditions they require for optimal growth and health.


  1. The Protea Grower’s Manual: Sustainable Nutrition and Irrigation, v.1.1,
  2. Protea Planting Guide – Proteaflora,
  3. Ornamentals – Acta Horticulturae,