Garden Lime: A Guide for Beginners
What is Garden Lime?
Garden lime, also known as ground limestone, is a natural material that is sometimes added to garden soils to improve their quality. It is made up of calcium carbonate, which is a mineral that helps to neutralize acidity in the soil.
Why Use Garden Lime?
Garden lime can be beneficial for soils that are acidic or low in calcium. It can help to:
- Improve the growth and productivity of lime-loving plants, such as vegetables from the Brassica family (cabbage, broccoli, kale, etc.)
- Improve the structure of clay and compacted soils, making them more crumbly and easier to work with
- Reduce the risk of clubroot disease in Brassica plants
How to Determine if Your Soil Needs Lime
Before you apply garden lime to your soil, it is important to test the soil pH to determine its acidity or alkalinity. A pH level of 7 or higher indicates alkaline soil, which does not need lime. A pH level below 7 indicates acidic soil, which may benefit from lime application.
Which Plants Need Limey Soil?
Some plants, such as those from the Brassica family, thrive in limy soil. Other vegetables that benefit from lime include beans, leafy greens, swedes, and tomatoes. For ornamental plants, it is generally better to choose plants that are well-suited to your natural soil conditions rather than trying to alter the soil pH.
When to Apply Garden Lime
Garden lime can be applied at any time of year, but it is best to apply it several months before planting so that it has time to become incorporated into the soil. For edible crops, apply lime in the autumn before spring planting.
How Much Garden Lime to Use
The amount of garden lime to apply depends on the natural pH of your soil and the type of soil you have. Clay soils require more lime than sandy soils, and loam soils fall somewhere in between. It is important to follow the instructions on the packaging or consult with a soil expert to determine the correct amount of lime to use.
How to Apply Garden Lime
Garden lime should be applied on a dry, windless day when the soil is damp or fairly dry, but not wet. Wear protective clothing, including gloves and a dust mask, to avoid inhaling dust. Ideally, incorporate lime thoroughly into the top 20cm of soil by digging it over after application.
Applying Lime and Manure
Do not apply lime and manure at the same time. Manure is rich in nitrogen, which can react with lime to release ammonia. This can damage plant roots and make nitrogen unavailable to plants. It is best to apply manure one year and lime the next.
Advice on Buying Garden Lime
- Make sure you buy garden lime and not quicklime, which is not suitable for applying to garden soils.
- Always test the pH and type of your soil before applying lime.
- Garden lime is widely available from garden centers, nurseries, and online suppliers in a range of sizes.
Additional Tips
- Avoid over-liming your soil, as this can raise the pH too high and make it difficult for plants to absorb nutrients.
- If you are unsure about how to apply garden lime, consult with a soil expert or your local extension office.
- Garden lime can be a valuable tool for improving the quality of your soil and helping your plants to thrive.
