Alum in Gardens: A Guide to Using Alum for Soil pH, Plant Diseases, and Pests

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Alum: A Versatile Substance for Gardens

What is Alum?

Alum is a naturally occurring mineral that is commonly found in the spice department of supermarkets and garden centers. It is a white powder that is made up of potassium aluminum sulfate. Alum is safe for household use in small quantities, less than one ounce (28.5 g.).

Uses of Alum in Gardens

Alum has a variety of uses in gardens, including:

• Improving soil pH: Alum can be used to lower soil pH, making it more suitable for acid-loving plants such as hydrangeas, azaleas, grapes, strawberries, and blueberries.
• Treating plant diseases: Alum can be used to treat a variety of plant diseases, including powdery mildew, black spot, and rust.
• Preventing pests: Alum can be used to prevent pests such as aphids, spider mites, and whiteflies.
• Making homemade fertilizers: Alum can be used to make homemade fertilizers that are rich in potassium and aluminum.

How to Use Alum in Gardens

When working with alum in the garden, it is important to wear gardening gloves and a dust mask or respirator to protect your skin and lungs. Alum that comes in contact with the skin should be washed off immediately.

To improve soil pH:

1. Test your soil to determine its pH level.
2. If your soil is too alkaline (above 7.0), you can add aluminum sulfate to lower the pH.
3. Follow the directions on the package of aluminum sulfate for application rates.

To treat plant diseases:

1. Mix 1 tablespoon of alum per gallon of water.
2. Spray the affected plants with the solution.
3. Repeat the application every 7-10 days until the disease is under control.

To prevent pests:

1. Mix 1 tablespoon of alum per gallon of water.
2. Spray the plants with the solution.
3. Repeat the application every 7-10 days.

To make homemade fertilizers:

1. Mix 1 cup of alum per gallon of water.
2. Add 1 cup of Epsom salts per gallon of water.
3. Add 1 cup of bone meal per gallon of water.
4. Stir the mixture well.
5. Apply the fertilizer to your plants according to the directions on the package.

Additional Tips

• Alum is a powerful substance, so it is important to use it carefully.
• Do not apply alum to plants that are already stressed or damaged.
• If you are using alum to treat plant diseases, be sure to follow the directions on the package carefully.
• Alum can be purchased in powdered or liquid form.
• Powdered alum is less expensive than liquid alum, but it can be more difficult to apply.
• Liquid alum is easier to apply, but it is more expensive than powdered alum.

Conclusion

Alum is a versatile substance that can be used for a variety of purposes in gardens. By following the tips in this article, you can use alum to improve your soil pH, treat plant diseases, prevent pests, and make homemade fertilizers.