LAWN MAINTENANCE To go for the green, use care when working with fertilizer

Don't just spread the stuff around. Know what you are doing.
KNIGHT RIDDER NEWSPAPERS
Spring brings out the best in pent-up energy.
Cooped up for months, you're eager to get outdoors to spruce up your property and enjoy some fresh air and sunshine.
Then the worst in you emerges.
Suddenly, you have a hard time resisting the urge to green up everything around you overnight.
You buy bags and bags of fertilizer, haphazardly spreading and tossing granules around everything that remotely resembles a plant.
The lawn really snags your attention. The grass is ragged looking from ice and snow, so you haul out the lawn spreader and let it roll.
Come on, grow and get green, you mutter as you put down fertilizer.
Take a breather
Whoa, stop the spreader and let's talk a little about what fertilizers really do. The proper use of fertilizers helps plants thrive; misuse harms plants and the environment.
The Virginia Department of Conservation and Recreation and Virginia Cooperative Extension offers these helpful hints on using fertilizers:
UFertilizers are not plant food. Plants produce their own food, using water, carbon dioxide and energy from the sun. It's the scientific process called photosynthesis.
When you apply fertilizer, you are really putting down a salt. If tender plant roots are close to the fertilizer roots, water is drawn from the roots. Plant cells in these roots begin to dehydrate and collapse, then roots "burn," or dry out to a point where they can't recover.
UUse fertilizer at the right time. Spring is the wrong time to heavily fertilize a cool-season fescue lawn; the proper time is three fall feedings between September and November.
Even if the fall feeding was missed, any spring feeding should be light -- about 1/2 pound actual nitrogen, or 5 pounds of 10-10-10 per 1,000 square feet after the first flush of growth has subsided, probably sometime in May or early June.
"The growth cycle [physiology] of the plant is to produce a lot of top growth," says extension agent Jim Orband of Yorktown, Va.
"It derives that top growth from food reserves collected in roots that it accumulated during the fall. When you add fertilizer, you further stimulate the top growth, which means you deplete root reserves and have to cut the grass every third day.
"You will not make your grass greener. That is a relationship of the availability of micro-nutrients in the soil, which is why you have to have the proper soil pH [soil acidity] of 6.2 to 6.5."
To get dark-green grass
There are some responsible ways to get dark-green grass, if that's your deep desire in life. You can plant darker-green grass varieties, which require less nitrogen and water. Or, you can periodically put down an iron-based product such as granular ones called Perk Up or Ironite.
Why do so many people feel the need to fertilize their lawn in spring?
Probably because they want to have the greenest lawn in the neighborhood, says Orband. It's a type of competition among neighbors.
"That never happens because your neighbor may have a different soil pH," he says.
He knows many of these societal gardening practices because he did extensive research on the origins of gardening habits for his master's degree.
"Or they may have more organic matter in the soil. And sun/shade relationships influence the growth."
If you have a warm-season Bermuda or zoysia lawn, you do just the opposite. Those grasses, which go dormant during cool weather, crave fertilizer in late spring and summer.
UApply the right amount of fertilizer. On your lawn, never apply more than 1 pound of soluble nitrogen per 1,000 square feet at any one time, and never fertilize when the grass is brown or dormant.
Trees, too, take some thought when it comes to giving them fertilizer.
Gardening experts say you should apply fertilizer over a plant's entire root zone, says Orband.
Consequently, the amount of fertilizer you apply depends on how many square feet of soil are covered by the plant's roots.
Here's how you do the math:
To determine a plant's root zone, you must first know the radius of the plant's roots. Root radius is at least twice the radius of the plant's crown. For example, if the branches of a tree appear to spread about 15 feet from the trunk, then the roots spread at least 30 feet.
To find the total square feet covered by the roots, use the formula 3.14 x (root radius) x (root radius).
For the example given above, the formula would be: 3.14 x 30 feet x 30 feet equals 2,826 square feet.
Once you know the total area in square feet covered by the roots, you can estimate the amount of fertilizer you need.
Different types of trees
When you fertilize evergreens, use 1 to 3 pounds per 1,000 square feet.
For deciduous plants that lose their leaves, use no more than 2 pounds of fertilizer per 1,000 square feet in one application, or you risk burning the plants.
Herbaceous perennials typically get a light feeding in early spring; annuals need regular feedings, especially to keep their bloom cycles going. Just place a small ring of fertilizer around each plant and use a small trowel to gently work in into the soil.
UAlways water a plant thoroughly after you fertilize it.
UGet to know fertilizers. Fertilizers are labeled with three numbers, which represent the percentage of weight of nitrogen (N), phosphate (P) and potassium (K).
Nitrogen stimulates leaf and stem growth; phosphorus promotes root and flower development; and potassium supports plant tissue and chlorphyll production.
Slow-release advantage
Slow-release fertilizers are the best way to go because they do what they say -- release nutrients in a slow but sure-fire way. The activators can be water or temperature, depending on the product.
Traditional fertilizers such as 10-10-10 or 8-8-8 contain nutrients that release all at one time when they come in contact with soil or rain.
Slow-release fertilizers are excellent for annuals and perennials that need constant feeding throughout their growing cycle.
Avoid using slow-release fertilizers too late in the growing season because they can cause new growth that fails to harden off before fall's first killing frost arrives.