Should You Use Epsom Salts for Gardenias?

You can easily remedy a Magnesium deficiency problem by giving your gardenias a dose of Epsom salts.

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Epsom salts are otherwise known as magnesium sulphate.

This product is useful for use on plants that are showing symptoms of a magnesium deficiency such as yellowing leaves.

Magnesium deficiency can be a problem if the soil pH is too low or acidic. Soil pH lower than 5.5 can often cause a magnesium deficiency in plants.

So, if your gardenias are displaying yellowing leaves and are not as healthy as you would like, they could definitely be suffering from a magnesium deficiency.

This is especially the case if you’ve been feeding them regularly but the older leaves are still turning yellow.

It’s important to keep in mind that gardenias grown in southern parts of the country may display some yellowing of the leaves in winter as this is their response to the cold weather.

You can easily remedy a Magnesium deficiency problem by giving your gardenias a dose of Epsom salts.

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How much Epsom salts for gardenias?

It’s generally recommended to mix up 20 grams of Epsom salts with 1 litre of water.

This amount should cover around 1.5 square metres of soil.

Here’s how to use Epsom salts on your gardenias.

How to use Epsom salts on gardenias

  • Use a watering can and add 1 litre of water.
  • Stir 20 grams of Epsom salts into the water and mix well.
  • Water this solution onto the soil around the drip line of your gardenias. Be careful to not splash any of the solution onto the foliage as it may burn.
  • Repeat with another dose one month later.
  • Continue with monthly applications until the gardenia is green and healthy again.
  • Remember to feed your gardenias with an organic fertiliser in spring and autumn to maintain healthy plants.

Remember to test your soil

Before starting on a dose of Epsom salts for your gardenias, it’s a good idea to test your soil to see whether it is acidic or not.

You can do this quite easily by purchasing a pH testing kit from your local garden centre or from a store like Bunnings.

If you find that your soil is highly acidic (a pH level below 5.5), then using Epsom salts on your gardenias to remedy yellowing leaves is a good idea.

Remember that gardenias like a soil pH of around 5.0 to 6.5. Therefore, you don’t want to change the pH level too much.

Frequently asked questions

What is the best fertiliser for gardenias?

Gardenias are quite heavy feeders, so a slow-release fertiliser is often recommended. It should be fairly well-balanced in that it contains a good amount of nitrogen but also ample amounts of phosphorus and potassium. Something like Dynamic Lifter would be ideal.

What else can cause leaves to go yellow on gardenias?

Apart from a magnesium deficiency, waterlogged soil can also cause your gardenia leaves to turn yellow. If this is the case, amend the soil with lots of organic matter and improve the drainage. 

Can you use coffee grounds on gardenias?

Like all acid-loving plants, gardenias do like the addition of coffee grounds to the soil around the base of the plant. Coffee grounds have high levels of nitrogen, magnesium, and potassium. This makes them ideal for gardenias.

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Annette Hird

Annette Hird has an Associate Diploma of Applied Science in Horticulture. She has worked in a variety of production nurseries, primarily as a propagator. She also had the responsibility of a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.