Welcome to LIME's Organic Living blog, where organic lifestyle expert Eliza Sarasohn — author of The Complete Idiot's Guide to Organic Living — tackles your questions on the ins and outs of living la vida organica. This week, Sarasohn shares the final three steps to giving your lawn an organic facelift.

Last week, I outlined overseeding and weed-whacking, the first two steps to making an organic lawn look good. As promised, this week, I'm taking a closer look at watering, mowing and organic fertilizing. (And if all this lawncare instruction is turning you green, tune-in for next week's blog where I suggest low-maintence alternatives to traditional lawns).  

Step Three: Feed the Grass

Plants produce their own food; this is what photosynthesis is all about. When you fertilize them, you’re giving them more of what they need to make their food (in other words, you’re giving them the ingredients for their meals, so they can do the cooking).

Like people and animals, plants need a variety of nutrients for optimal health—17 of them, in fact. They get most of what they need from healthy soil, which is why organic gardening so emphasizes soil health. But they need larger doses of three main nutrients—nitrogen, phosphorous, and potassium—than what they can typically draw from the soil.

The best way to gauge your lawn’s nutritional needs is by doing a soil test. This is different from gauging texture and structure, as it yields a scientific assessment of the soil’s chemical composition, not its physical composition. There are two basic types of soil chemistry tests—ones you can do yourself and ones you can’t. Do-it-yourself tests are available at most lawn and garden stores. They’ll tell you the pH level in your soil but they typically don’t go much beyond this. pH levels are good to know, but unless they’re really out of whack, they typically aren’t much of a concern, so it’s best to skip these kinds of tests unless they’re all that’s available.

More complex tests measure pH levels and the levels of the most important plant nutrients—nitrogen, phosphorous, and potassium—plus two others—calcium and magnesium. Check with your county extension agency to see if they offer tests like these. Many do. If not, you can always hire a local company to do the job.When you receive your test kit, simply follow the instructions, send off the soil samples, and wait for the results. When you get them back, follow them. They’ll tell you what your lawn needs.

Nitrogen is typically the nutrient that’s applied in the largest amount because it’s what grass requires the most of. Simply leaving grass clippings on your lawn after mowing can provide up to 2 pounds of nitrogen per 1,000 square feet, which is close to if not all the nitrogen your grass should need. Nitrogen needs can vary quite a bit, but as a rule lawns require between 3 and 4 pounds of nitrogen per 1,000 square feet every year.

Regular applications of compost and compost tea should satisfy most of the rest of what your grass needs, but depending on your soil test results you might need to supplement these nitrogen doses with fertilizer.

If you need to buy fertilizer, look for products labeled “natural organic.” Products labeled “organic based” can contain synthetic ingredients. Organic fertilizers can be plant based, animal based, or mineral based. They differ from synthetic fertilizers as they need soil microorganisms to break them down. As a result, they also work more slowly.

Step Four: Water it Right

Two words—infrequently and deeply—are what you want to remember when it comes to watering. Infrequently because most plants do better when the soil dries out to a certain extent between waterings, and because wet soil can cause pest problems and plant diseases. Deeply because doing so builds deeper, healthier root systems, since the roots have to dig down for the moisture rather than taking it up at the soil surface. (This is another reason why maintaining an appropriate thatch level is so important; if there’s too much thatch at the soil surface, it will collect both water and grass roots.)

The exact amount of water your lawn needs depends on the kind of grass you’re growing, the type of soil under the grass, atmospheric conditions, the time of year, and so on. As a general rule, about an inch every week—applied by you or by Mother Nature—is enough to keep an established lawn looking green and healthy.

You can see if you’re getting enough water down deep by checking the root zone—the area in which the roots are growing. Simply sink a shovel or spade into the soil after you’ve watered and pull back a spot of turf, enough so that you can examine what’s going on underneath the grass. Ideally, you’ll see about 3 to 6 inches of roots extending into the ground, and, hopefully, you’ll observe evidence of water going down that deep as well.

You can check water penetration during the growing season by sticking a long screwdriver or something similar into the turf after watering; much like testing a cake when baking, if the screwdriver comes back moist and a little crummy when you pull it out, moisture levels are probably good. If it comes back dry and relatively clean, you’ll want to take a closer look at your watering practices.

If possible, water early in the morning. Doing so reduces moisture loss from evaporation and will help prevent fungal diseases.

Step Five: The More You Know, The Better You Mow

Mowing heights also vary depending on the type of grass, but in general, longer is better. For cool-season grasses (bluegrass, ryegrass, fescues, etc.), plan on keeping them at about 3 inches in length. Don’t let your grass get too long; you never want to cut off more than one third of the blade at any time.

Other good mowing practices:

•    Keep mower blades sharp, as dull blades will tear rather than cut grass, making it more susceptible to diseases. Dull blades also dry out the grass.

•    Change your mowing patterns from time to time. Mowing in the same direction every time can lead to soil compaction.

•    Leave the clippings on your lawn. As they decompose, they’ll add organic matter and nitrogen to your lawn.

Taking your lawn organic doesn’t necessarily mean ditching fossil-fuel driven lawn implements, but continuing their use will be somewhat at cross purposes with what you’re working toward.

Lawnmowers and other gas-powered lawn tools emit several types of pollutants, including ozone precursors, carbon dioxide, and polycyclic aromatic hydrocarbons—the last is classified as a probable carcinogen by the CDC. Consider exchanging gas-powered devices for ones powered with electricity or powered by you.

According to a Swedish study conducted in 2001, the air pollution generated by cutting grass for one hour with a gasoline-powered lawnmower is nearly equal to what you’d create if you drove your car for 100 miles. Multiply this by the estimated 54 million Americans who mow their lawns every week with gas-powered mowers, and you’ll see how gas-powered mowers make a significant—and negative—impact on the world around us.

If you want to or have to keep your gas-powered equipment, reduce emissions by maintaining it properly. Change the oil and clean or replace air filters regularly. If you’re using two-stroke equipment, use the correct fuel/oil mix.

Ready to get rid of your old gas-powered lawnmower for good? Don’t just junk it—see if your city or county offers central collection of old lawnmowers for recycling.

Excerpted from The Complete Idiot's Guide to Organic Living by Eliza Sarasohn with Sonia Weiss.