Your guide to using lime in the garden

If your garden's soil is too acidic, adding lime can bring it up to the right pH so your plants can take up the nutrients they need. Here's what you need to know about using lime in your garden.

Some gardeners lime their lawns and garden beds annually, which isn't always necessary.

• Test your soil's pH before deciding that you need to add lime.
• If the pH reading is below 6.0, liming is necessary to help plants take up all the nutrients they need.

Lime is basically ground rock, so it doesn't dissolve in soil quickly.

• For this reason, fall is the best season in which to lime since that allows time for the lime to work before spring planting season.
• You can add lime in winter, spring, or summer as well, but keep in mind that it takes two or three months to work.

• If you are cultivating soil, dust or broadcast the lime over the surface, then mix it in.
• When liming your lawn, apply the lime to the surface and water it in thoroughly.
• If your soil is extremely acidic, and you need to raise the pH drastically, make several applications of lime over time, using no more than 2.3 kilograms per nine square metres at once. Too much lime applied at once will burn plant roots and poison beneficial soil microorganisms.

Lime is available in several forms, with each having a different application in the garden. It's used to provide calcium, decrease soil acidity, and condition heavy clay soil.

• Calcitic lime (calcium carbonate) is the most common and least expensive. Typically sold in 23 kilogram bags, ordinary lime is made from finely ground limestone rock.
• Dolomitic lime is a mixture of calcium carbonate and magnesium carbonate. Its advantage over ordinary lime is that it adds both calcium and magnesium — two essential plant nutrients — to the soil. Dolomitic lime is available as a powder, or you can buy it in granular or pellet form.
• Burnt limeor quicklime is calcium oxide; it's lime that has been heated to release carbon dioxide. It was once used as a wash for tree trunks but is rarely used by modern gardeners.
• Hydrated or slaked lime (calcium hydroxide) is burnt lime that has been treated with water. It's a caustic pesticide and fungicide and can be dangerous to handle.

• All forms of lime are caustic, so wear gloves to protect your hands and wash it off your skin immediately.
• Wear a dust mask when handling powdered lime, and work on a still day.

Pelleted or granulated lime is easier and safer to handle because it releases fewer airborne particles.