How to Amend Soil to Grow Giant Tomatoes

Test the soil for available nutrients, pH level and trace elements prior to amending. Your local extension office provides soil testing services for a nominal fee, which includes a detailed report of the makeup of your soil. Follow the recommendations to balance nutrients and adjust the pH to between 6.2 and 6.8.

Spread a 2-inch layer of compost, or a 2- to 4-inch layer of finely chopped leaves, over the gardening area in the fall. Till this into the existing soil with a garden tiller. Allow the organic matter to break down in the soil over the winter.

Dig a hole for each tomato plant to the recommended spacing in the spring. Typically 36 to 48 inches between tomato plants is required. Dig the hole to a depth of 12 inches and remove the existing soil until you have removed enough to fill a 5-gallon bucket.

Remove one-half of the soil from the bucket. Fill the remaining portion with compost. Mix the soil and compost until blended. This creates organic-rich soil preferred by tomatoes.

Pour the soil and compost mixture back into the planting hole. Compost improves aeration, promotes drainage and adds slow-release nutrients to the soil. It also improves the soil's ability to retain water and nutrients.

Plant your tomato seedlings following their recommended spacing. Many gardeners prefer to plant deeply, positioning the tomato plant so that only the top 4 to 6 leaves extend above the surface of the soil. Others prefer trench planting, which involves laying the seedling on its side and curving the top above the soil. Fill in around the stem with soil and firm it down to secure the plant. Roots form along the stem providing a strong root system.