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Grow a Great, Green Lawn

Now’s the time to get to work, says the Bay Gardener

Feeling less than pride and joy in your lawn?
    September is a great month for establishing and repairing lawns. Here’s how to get started now on growing rich, green, weed-free grass in 2014.

1. Test Your Soil
    How’s your lawn doing?
    There’s no way to know without soil testing. Fertilize without testing, and you’re not only throwing your money away but also polluting the Bay.
    Don’t bother with do-it-yourself-test kits. They don’t work.
    Professional testing is what you need. It’s quick, simple and affordable: about $10 a test for lawns.
    I recommend A&L Eastern Laboratories of Virginia: www.al-labs-eastern.com.
    In most cases the S1 test is adequate ($10). If your lawn is located near the Bay or ocean, choose the S2 test. If your soil is sandy, choose the S3 test. These options cost a few dollars more.
    If the appearance of your current lawn is uniform, a single sample should be adequate. If the front lawn is better than the side or back lawn, submit separate samples.
    Make each sample from a composite of five or six core samples taken at a depth of six inches. Mix the samples in a clean bucket and remove a cupful for testing.
    Air-dry and mail. Expect results by mail within five working days. Replies by e-mail take even less time. Add my e-mail address to the form — DR.FRGouin@gmail.com — and I will give you personal recommendations based on the results.

2. No Soil Test? No Fertilizer!
    Conventional lawn fertilizers supply a standard mix of elements that may be all wrong for your lawn.
    Most fertilizers are dominated by nitrogen (N), phosphorus (P) and potassium (K).
    A good basic lawn fertilizer is the 10-6-4 formula. The numbers represent proportions of N-P-K, with nitrogen always first, phosphorus second and potassium third. Many other formulas are marketed. How do you know which to use?
    Test your soil, because not all lawns need P or K — or even N.
    If your soil test results indicate that you have high levels of either phosphorus or potassium and you continue to add more through fertilizer, you are pouring these elements into the Bay by way of surface runoff or leaching through the groundwater.
    High levels of phosphorus in your soil could also be denying your plants’ roots iron, zinc, molybdenum, copper and other minerals. Too much phosphorus, however, stunts plant growth.
    Medium levels of phosphorus and potassium are all you need to keep your lawn growing green. A single application of potassium every two to three years is fine unless your soil is very loamy and sandy.
    Most likely all your lawn needs is nitrogen, which is available in numerous forms: urea (46 percent nitrogen); ureaform (38 percent in a slow-release form); ammonium nitrate (33.5 percent); ammonium sulfate (21 percent); calcium nitrate (15.5 percent); and dried blood (10 percent).
    The results of your soil test and my recommendations will tell you how to choose the right fertilizer for your lawn.
    September and October are the best time to fertilize cool-season grasses like fescue, bluegrass and ryegrass. But before you fertilize, see No. 4 below.

3. When in Doubt, Add Lime
    You get a bigger bang for your buck by applying lime instead of fertilizer.
    Lacking the knowledge soil testing gives you, it’s a safe bet your soil is overly acidic. Rain has a pH of 5 or below, so rain drops acid on your soil. Neutral is 7, which means our rain has a pH 200 times more acid that distilled water.
    Nearly all commercial lawn fertilizers also acidify soil.
    Lime will raise the pH of the soil to a more desirable level for plant growth and help roots better utilize other nutrients. Beyond neutralizing acid, lime supplies much-needed calcium and magnesium.
    It also helps break down the thatch that accumulates from frequent mowings. Even if your lawnmower catches your lawn clippings, 10 to 20 percent of the clippings settle between the blades of grass and accumulate on the surface of the soil. This is especially true if you mow your lawn short. If your soil is too acid, thick thatch accumulations will not rot.
    My recommendation for untested soil is to apply 60 to 80 pounds of garden lime or agricultural grade dolomitic limestone per 1,000 square feet of lawn. Do not use hydrated lime.
    If you apply before a rain, your lawn won’t look like a dusting of snow has fallen too early.

4. Top-Dress with Compost
    Evenly spread between one-half and one inch of compost over your existing lawn. Use the back of a steel rake. Plan for two to four cubic yards of compost per 1,000 square feet of lawn.
    Use our own compost or a commercial formula such as Maryland-made LeafGro. If you can purchase the compost by bulk, it will be much cheaper than by bag. One bag of compost contains approximately one cubic foot. One cubic yard contains 27 cubic feet.
    The compost will rot lawn thatch and release nutrients at the same time. If you use compost, you don’t need any chemical fertilizer.

5. Finally, Sow New Grass Seed
    Spread seed as uniformly as possible over the compost.
    If sowing fescue, use seven to 10 pounds of seed per 1,000 square feet. For a bluegrass lawn, use five to seven pounds per 1,000 square feet.
    Next, spread the compost with a lawn rake so the existing blades of grass poke up through it. This will help shade the seeds and emerging grass.
    Water the newly seeded lawn daily until the seeds germinate in about two weeks. Then water two to three times a week until your new grass is as tall as your existing grass.