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Preparing your Soil, Grading, and Edging

by Dawn West, All About Lawns Columnist

After you have planned out how you want your lawn to look, the next step is to put your plans into action. If you are replacing your existing lawn, you will first need to get rid of your old lawn. Most people will choose to kill-off the old lawn with a broad-spectrum herbicide such as RoundUp or glyphosate before they begin to plant. Once the grass and weeds are dead, they are tilled into the soil.

For those of you planting a new lawn from scratch, you will first need to determine is what kind of soil you have, what kind of soil you need, and how you want to grade your lawn.
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What kind of soil you have:



One of the most overlooked, yet important factors in growing a healthy lawn is your soil composition. Your soil is the foundation for a healthy lawn, and once established, cannot be changed unless replanted or renovated. So it's important to establish the proper soil base before you begin planting.

There are three different types of soil - Clay, Loam , and Sand. Most people don't have a purely clay or purely sandy soil, but have a combination (i.e. sandy-loam, Clayish-Loam, etc.). We have put together 3 general descriptions to help determine what type of soil you have and its relative properties:
  1. Clay: Clay soils are made up of tiny particles that cling together and subsequently cling well to water. To help determine how much of your soil is clay you can simply take a handful of your soil and try to squeeze it together. Once squeezed, release your fingers and see if the soil is still in a ball. The more clay it has, the more solid and less-brittle it will appear. Although it is not unique to any one place, you can usually find an abundance of clay soil in the southeast portions of the U.S.
  2. Sand: Sandy soils are made-up of less-dense soil and sand particles that have much poorer moisture and water holding properties than clay. To help determine how much sand is in your soil, you can simply take a handful of your soil and squeeze it together (the same as we did with the clay). Once squeezed, release your fingers and see if the clump of soil falls apart. Unlike clay, sandy soil will not cling together well and should break apart in your hand after squeezing. Although it is generally not unique to one place, you can usually find an abundance of sandy soils in the southwest regions of the U.S.
  3. Loam: As you've probably already guessed, loam is a combination of sandy and clay soils. In fact, most people tend to have some sort of this combination in their lawns. But for purposes of comparison, it is good to think of the extremes so you know where in between your soil may be. When applying the same squeeze test we used with the previous soil types, loam will be somewhere between the solid ball of clay and the brittle mass of sand. In short, only you can determine what kind of lawn you want and can manage. Once determined, you should have a good idea of what kind of soil combination will best fit your needs!

To understand to watering properties of these soils, see the section on: How does the soil affect my watering.

What kind of soil do I need?



Once you have determined the type of soil you have, the next step is to determine the composition of the soil. This can be accomplished by sending samples to a professional soil testing laboratory near you, or simply purchasing a home-testing kit and doing the test yourself. By testing your soil, you are determining the pH balance, and how much nitrogen, phosphorus, inorganic amendments, and Humus (organic amendments) you need to add to your soil. By amendments, we are talking about those things you add to your soil to improve its composition and texture. There are two common types of amendments used in soil:
  1. Humus (Organic Amendments): Humus is the decomposing remains of animals and plants that were once alive. They are commonly used in sand and clay soils to improve both aeration and water drainage and penetration. They also provide your soil with added nitrogen. The most commonly used forms of humus are: peat moss, shaved tree bark, manure, sawdust, leaf mold, wood shavings, and sawdust. Just remember that humus from wood tends to be low in nitrogen so make sure to add any additional nitrogen accordingly. Click here to find a Humus dealer near you!
  2. Inorganic Amendments:- Inorganic amendments are commonly used with Humus to provide nutrients and elements that the particular humus used may not provide. These amendments often come in a powder or granular form and should be mixed in with the humus when tilled. The most common types of inorganic amendments are lime, gypsum, sulfur, and iron. Lime adds calcium to soils, creates clumps in clay soils (increasing aeration), and raises the pH of acidic soils. Gypsum is commonly used on soils low in minerals and provides both calcium and sulfate to the soil. If you have areas of your lawn with highly compacted clay soil, you may want to try applying EnviroMax to help prepare the soil and break through the clay spots. Click here to find a inorganic amendments dealer near you!

The following are common soil deficiencies found in the U.S.:
  1. Alkaline Soil: Alkaline soils are common in areas of light rainfall and soils high in sodium and lime. The common amendments added to improve these soils are: peat moss, ground-up bark and wood, and sulfur.
  2. Acidic Soil: Acidic soils are common in areas high in sandy and/or humus soils and rainfall. Lime is the common amendment added to improve these soils.
  3. Chlorosis: Chlorosis is commonly found in soils that are iron deficient and have poor drainage. Many times, new lawns will look yellowish when they have chlorosis. The common amendments added to improve these soils are: iron sulfate and iron chelate. Improved drainage will also help.
  4. Salty Soils: Salty soils are those heavy in salt thereby inhibiting proper grass germination and growth. Gypsum is the common amendment added to improve these soils. Improved drainage and a good saturation of water (by leaching) will also help with salty soils.
  5. Hard Pan: Hard pan is a shallow layer of soil near the surface that is so tightly compacted that grass roots have a hard time penetrating into the soil and water cannot drain through it. As we know from the section on "How much should I water?", most grasses need a deep root system to help survive conditions of drought and water shortages. Commonly found in lawns where construction or other heavy vehicles drove over prior to planting, hard pan requires that the soil be re-tilled and re-worked to soften it up. If re-tilling your soil is not an option, you may want to try applying EnviroMax™ to help break through these layers and improve the soil structure.


Grading your lawn:

Once you have determined what amendments you need to add to your soil (if any), your next step is to properly grade your lawn. There will be two grades you need to give your lawn before planting your grass: Rough Grading and Final Grading, both discussed below. Before we begin, it must be emphasized that each city, county, and state have different rules when it comes to planting a lawn. Some locations (usually areas with high regulations) may even require permits and inspections. So make sure you check with your local building departments before you begin. If you are planning a major planting and/or renovation, most landscape architects and contracts will do this for you. Click here to find an architect or contractor near you!
  1. Rough Grade: This is your first grading where the slope, soil composition, and drainage will be determined. There are also other factors to consider such as existing trees, pools, walkways, driveways, etc. that may effect how you want to grade your lawn. If you plan on moving more than a few inches of soil, you will need to identify and mark with flags all the buried lines in your yard for your phone, gas, cable, water, electricity, etc. before you begin.
    • Slope: You should always try to grade the slope of your lawn away from your house and towards a drain sewer or other drainage area. Your neighbors yard is not considered a drainage area so make sure the excess water runoff goes to the desired location. If you ever noticed an old house with water damage in the basement, you can appreciate the need for water drainage away from the house. As a general rule, the slope of your lawn should at least descend at a rate of 1 foot per every 50 feet from your house. This should allow excess water to drain from your yard, but not at rate that will prevent moderate amounts of water to penetrate your lawn. For people who live on steep slopes, creating a terrace can help retain water while still creating a slope away from their house.
Ideal Finished Grade
Ideal Finished Grade from Home

Poor Grading
Poor Grading Away from Home
Terracing
Terracing Grade Away from Home
The two most common ways to determine the slope of a lawn are through the use of strings with a string level (shown) and by placing a leveling bar on a 8 foot long 2X4. The method of using a string is accomplished by placing one end of the string at the base of the house and extending it out 50 feet to a vertical stake or pole. Place a string leveler in the middle of the string and raise the end attached to the stake until the string leveler shows that the string is level. Then measure the string's distance from the ground (at the stake) to determine the slope. If it's 1 foot off the ground, then you have 1 foot of slope for every 50 feet. The other method of placing a leveling bar on a 8 foot long 2X4 can work in the same fashion as the string but can actually work better in smaller areas. Simply lay the 2X4 down on the slope away for the house with the leveling bar on top. Raise the end of the 2X4 that is the farthest away from the house up until the leveling bar is level. If the distance raised by the end of the 2X4 from the ground is 2 inches, then the slope would be roughly 1 foot for every 50 feet away from the house.
Slope of Lawn
Slope of Lawn
  • Soil Composition: Once you have determined what amendments need to be added to your soil (if any), your next step is to finish the slope of the lawn and add the amendments.
  1. Any low spots will need to be filled, and any high spots may need to be leveled at this time. Since most lawns have 6-8 inches of topsoil, it is best to remove any topsoil from those areas that need filling and then placing the topsoil back when finished. The same applies to removing high spots. When leveling, it is best to create two separate piles (one for the topsoil, and the other for the subsoil) so the two are not mixed in the process.
  2. Once you have achieved the desired slope,your next step is to rent a tiller and add the soil amendments (click here to find a tiller rental location near you). Once added, you will need to till the soil so that all the amendments are mixed-in the soil. You should till your lawn much like you mow it only make sure that you take a few passes in crossing directions for best results.
  3. If you are considering a sprinkler system or adding a drainage system, this is the best time to do it. Since the ground is still loose and unfinished, installation usually takes less time and effort. If you need additional water drainage, now is a good time to install a drainage trench or well. A drainage trench will typically have a buried flexible pipe that will carry water from one part of your yard to another. Just remember that when installing the pipe, it too should slope away from the source location at about 2-3 inches per every 10 feet of pipe. If you need to trap water in certain areas and have no other drainage options, a drain well may work. Simply dig a 2-4 foot wide hole 3-4 feet deep and fill with small rocks. Place an water-soluble material on top and cover with topsoil and grass. The well should hold water and slowly release it into the soil over time.
  • Final Grade: Once you have created a slope, provided additional drainage (if needed), amended the soil, and installed a sprinkler system (if desired) -- then it's time to smooth-out the surface for planting. You may still have debris, rocks, large chunks or soil, and uneven places you will now need to remove and level out. Take your leveling bar and a rake and smooth-out the soil until it is free of large debris and level. Then use the back of your rake to make a final smooth surface.

Edging:



To help minimize lawn maintenance, now is a good time to create edging boundaries for your lawn. If you are planting a "creeping grass", have a garden, have a neighbor with a different type of grass, or just hate trimming your lawn after every mowing, then edging may be a good investment. As you can see from the illustrations, edging can be done with wood, stone, plastic, bricks, and even cement.

Surface level edging will allow you to run your mower wheels along the edging to help achieve a even, trim-free cut. If you're planting a garden, tree island, or plants along the house, edging will help prevent your grasses from invading the space you created. Edging can also help retain water in these areas if they are on a slight slope or depth to the lawn. Edging may take a little time to install now, but it should be weighed against the time you plan on spending in the future to trim and maintain your lawn without them. To most people, the answer is pretty clear.
Edging with Plastic
Edging with Plastic
Edging with Brick
Edging with Brick
Edging with Wood
Edging with Pressure Treated Wood
Edging with Timber
Edging with Timber


About the Author
Dawn West B.A. holds a B.A. in English from Harvard University and teaches writing at Oregon State University.

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