Lowe's Home Improvement

Soil and Soil Amendments Guide

Soil Amendments

Use compost and other organic additives to improve your soil's quality and give your plants the nutrition they crave.

Improve Your Garden Soil

The plants in your garden need a variety of nutrients to grow healthy and provide optimal blooms, fruits and vegetables. The source for these nutrients is the soil around your plants.

It's important, periodically, to check your soil to make sure it has the proper nutrients, to correct drainage problems or to help sandy soils retain moisture better.

Soil texture is determined by the amount of clay, silt or sand particles present. Clay holds water and nutrients very well but is tough for roots to penetrate. The other extreme is sand, which drains very well, but also quickly leaches away nutrients and dries quickly.

The best type of soil for gardening is loam. Loam has proportional amounts of silt, clay and sand that cause it to hold its shape when lightly squeezed. If you don't already have the perfect soil, add organic matter or soil amendments to help.

Before you plant in the spring, add soil conditioners to make sure your new plants get the best start.

Shop Bagged Mulch, Rock and Soil

Test Your Soil pH

Determine what your soil needs before you improve it. You can diagnose poor drainage simply by looking at the soil, but determining nutrient content requires a test.

The perfect soil for optimal plant growth will have the proper pH level. pH is measured on a scale of 1 to 14. A measurement of 7.0 is neutral, below 7 is acidic (sour) and above 7 is alkaline (sweet). Soil pH signifies a plant's ability to draw nutrients from the soil. A soil test will enable you to adjust your soil's pH level. Buy a home soil testing kit, or contact your local cooperative extension agent for a test package. The soil test will determine whether it's neutral, alkaline or acidic. Most plants prefer nearly neutral soil with a pH between 6.2 and 7.2. To achieve this goal, you might have to apply lime to acidic soil or some sulfur to alkaline soil.

Improve Soil in Existing Beds

Step 1

Break the soil up 2 to 3 inches deep around existing plants using a garden fork or a steel rake. Chop up larger chunks and turn the soil.

Step 2

After you've determined what conditioners or amendments your soil needs, sprinkle them on the soil. Use a garden fork or rake to blend the conditioners evenly.

Step 3

Rake in a single direction to level the area, and then rake again in the opposite direction.

Step 4

Water the area thoroughly.

Improve Soil in New Beds

Step 1

A few days before you plant, water the area thoroughly. Wet soil is hard to work with and might not blend well with soil conditioners. Wait until it dries before attempting to add your amendments.

Step 2

Use a rotary hoe, running in parallel lines. Make two passes over particularly stubborn areas.

Step 3

Spread the conditioners you're using evenly over the top of the soil.

Step 4

Run the rotary hoe again over the soil to blend the conditioners to a depth of 6 to 8 inches.

Step 5

Rake the surface and water to prepare the bed for your plants.

Learn About Common Soil Amendments

Most soils need help in order to improve drainage, increase moisture retention, provide aeration and supply organic matter. Many gardeners choose to make their own compost using fruit, vegetable and other household scraps, while others purchase soil amendments.

If you aren't composting, consider choosing quality prepackaged soil amendments:

Builder's sand is natural sand with grains larger than beach sand that can help with drainage problems by loosening soil.

Compost manure is an odorless, organic farm by-product used as a plant food to enrich potting mix and seedbeds. Dehydrated manure is basically the same with less moisture.

Humus consists of decayed organic matter used as a soil amendment to add fertility, hold moisture and provide aeration. You can produce your own humus by growing ryegrass or soybeans during the winter and then plowing them under as a kind of green manure. You can also dump lawn clippings and raked leaves into a pile to create your own humus through natural decomposition.

Limestone is a natural white powder left over from mining procedures that can help lower soil acidity.

Sphagnum peat moss is completely organic, odorless and natural. Peat moss absorbs water up to 20 times its dry weight; the absorbed water is then slowly released to plant roots. Sphagnum peat moss aerates and lightens heavier soils such as clay. It adds mass to sandy soils to reduce the leaching of nutrients.

Peat moss is a regular ingredient in planting mix recipes for container plants. But don't confuse it with plain sphagnum moss, which is mostly used by floral designers.

Topsoil is commercially produced compost that's usually partially decomposed. Because of its rough texture, use topsoil in the yard or mixed with other products, and not as a potting soil.

Mushroom compost is a mixture of straw, peat moss and other organic components. Its sole purpose is for commercial mushroom production. The mixture is only used once for mushrooms and is a great by-product for the garden.

Learn About Packaged Soils

Container gardening or planting beds are formulated primarily for starting seeds. Quality potting soils and mixes are essential to get the best results from your plants. These products provide good water-holding capacity while also providing appropriate drainage.

The types of packaged soils you'll find in the Garden Center include:

All-inclusive soil mixes, which contain various blends of premium potting mix, fertilizer, pest control and water retention elements. These mixes are excellent for containers and planting beds.

Potting mix is the best choice for potting or repotting. Potting mix should contain organic matter, as well as elements for aeration and moisture retention (perlite and vermiculite). Charcoal may also be an ingredient.

Professional grower's mix is also known as greenhouse mix. Because of its fine texture, it's very good for starting seeds. But for the same reason, it will also dry out very quickly.

Planting mix contains compost and sand, and is recommended for outdoor use, not houseplants.

Forget the Guesswork