How to Add Lime to Garden Soil

Published September 10, 2019
Gardener puts lime or calcium hydroxide into the soil to neutralize the acidity of the soil

There are several reasons you may want to add lime to your garden soil, but you need to know when and how much to add. The main reason to add lime to your garden soil is to change the soil pH (potential hydrogen) to ensure healthy and abundant crops.

When to Apply Lime to Garden Soil

There are two times during the year you can choose to add lime to your garden soil. Depending on your circumstances, you may choose the timing best suited for your garden.

Apply Lime in Fall

Seasoned gardeners will tell you the best time to add lime to your garden soil is at the end of the fall growing period. This will give the soil time to absorb the lime and for the soil pH to adjust. It takes several weeks for the lime to work its way into the soil. It depends on the type of soil and the current soil pH level. You should add lime immediately after your last harvest.

Adding Lime in the Spring

You aren't limited to adding lime only in the fall. You can wait and add lime to your garden soil in the spring. However, this should be done several weeks before you plan to sow your garden. The more lead time you have, the better the lime nutrients will be worked into the soil.

How to Add Lime to Garden Soil to Change Soil pH

Lime is used to increase the soil pH and may be necessary if your garden soil is too acidic. Most vegetables prefer an alkaline soil versus an acidic one. The pH range is usually between 6 to 7, although some gardening textbooks state 5.5 to 7 pH levels can support most vegetables. It's universally agreed that pH 7 is the neutral pH level and generally believed to be suitable for the most vegetables and flowers.

Shovel garden soil

Step One: Test Soil pH

You can test your garden soil pH with a multi-use soil kit. You'll want to spot check the soil in several places where you intend to plant vegetables or flowers to ensure an accurate overall soil evaluation.

Step Two: Calculate Lime Needed

You need to determine how much lime is required for the size of your garden. Different soil types have different requirements for amendments like lime. You want to raise any pH level that is below 6.5. The following table is calculated for the amount of lime needed for every 100 square feet of garden soil.

Soil Type pH Reading Lime Needed
Clay Soil 5.0 28.5 lbs
5.5 11.5 lbs
6.0 4.5 lbs
Sandy Soil 5.0 10.5 lbs
5.5 4.3 lbs
6.0 1.5 lbs
Loam Soil 5.0 21 lbs
5.5 8.5 lbs
6.0 4.5 lbs

Step Three: Two Ways to Spread Lime in Garden

There are two ways you can broadcast the lime in your garden. Both ways have good results. The old-fashioned way is to spread it using a shovel. You want to spread the lime evenly over the top of your soil. The second way is to spread lime in your garden with a garden/agricultural spreader. You should wear a protective breathing mask and goggles.

Step Four: Till Lime Into Your Garden

Once you've broadcasted the lime over your garden soil, you need to till it into your garden to make sure it's well mixed. If you use a manual method, such as double digging, you want to turn the soil upside down when you place it in the previously dug row. Be sure you till or dig down to the depth your plant root systems will grow. This is usually around 12 inches. Simply spreading powdered lime over the top of the soil won't provide much, if any, benefit to your plants.

Man cultivates the land with the cultivator

Step Five: Soak Garden

You will need to activate the lime by adding water to your garden. Soaker hoses are best for this task, so they can slowly saturate the ground and filter through to the limestone.

Step Six: Avoid Sowing Garden Immediately

If you choose to apply lime to your garden soil in the spring, you want a minimum of three weeks between spreading/tilling lime and sowing your garden. The longer you can wait, the better the lime will be distributed in your garden soil.

Benefits of Applying Lime to Garden Soil

Besides raising the pH level of acidic soil and making it more alkaline and conducive to vegetable and flower production, lime supports other nutrients, such as nitrogen. Adding lime to your garden soil improves water penetration and with the raised pH, the plant nutrient uptake increases. Lime supports healthy soil bacteria and beneficial microbes.

Lime for Field and Raised Bed Gardens

A field garden can often demand the reapplication of lime, due to an unusual rainfall and/or a large field nutrient depletion. Raised beds don't need as much lime as an open field since most of the nutrients in the soil are contained and don't deplete with rain runoff.

Growing Vegetables in Acidic and Alkaline Soils

Some vegetables can grow in either alkaline or acidic soils while others like potatoes and parsley prefer acidic soil. You don't need to add lime to your garden soil to grow either of these.

Vegetables That Love Lime in Soil

Many vegetables prefer a pH between 6 and 6.5. If your soil pH is less than 6, you need to add lime to bring it up to a more favorable level.

  • The vegetables happiest when adding lime to your garden soil include, beans, cabbages, peas, spinach, lettuce and other leafy vegetables.
  • Tomatoes won't grow well in acidic soil. Lime provides needed calcium and magnesium in the soil.
  • You don't want to add lime to a pH neutral soil (7 pH) since it is already at an optimum pH level.

Knowing How to Add Lime to Garden Soil

Any vegetable or flower garden will benefit by adding lime to garden soil that is acidic. Knowing when and how to add lime can mean the difference between a high yield and a struggling garden fraught with disease and malformed vegetables.

How to Add Lime to Garden Soil