WHEN TO FERTILIZE
In most of the midwestern and northeastern United States you should fertilize your lawn 2 to 3 times per year:
EASY WAY TO REMEMBER
Memorial Day, Labor Day and Thanksgiving
(skip Thanksgiving for 2x year schedule)
This timing of applications is conducive to the natural growth cycle of grasses and using this "holiday schedule" makes it easy to remember!
The real difficulty with designing your own lawn fertilization program is being able to address the potential need for weed and insect controls. That's why homeowners often find it easiest to use something like a "1-2-3-4" program which is often called a "weed & feed" program.
Combination products with the 1-2-3-4 schedule are quite popular since they usually have "everything" included for those applications during particular seasons of the year:
Always read and follow label instructions.
HELP PRESERVE WATERWAYS
Sweep fertilizer off walks and driveways onto the lawn to help minimize the likelihood of it reaching waterways and having detrimental effects.
If you don't wish to use herbicides, insecticides and chemical fertilizer, consider using an organic fertilizer such as the old golf course favorite, Milorganite. This processed Milwaukee sewage sludge has a 6-2-0 analysis fertilizer with a hardy 4 percent Iron. Other organic fertilizers have become more available on the market. Generally speaking, expect to pay more for organic fertilizers than chemical fertilizers.
A successful lawn fertilization program promotes vigorous growth that chokes out invasive weeds. However, over-fertilization should be avoided since it will produce excess lawn thatch and contribute to the severity of most turfgrass diseases.
Therefore, it's always best to have a well-designed and well-timed fertilization program, without overdoing it. Bob strongly recommends beginning with a soil test when seeking the best possible results for your lawn and re-testing soil every 3 to 5 years. Also, work with the natural growth cycle of your lawn and don't fertilize your lawn during hot, dry weather during summer when grass is dormant.
Want to avoid lawn striping? Then split your total fertilizer application in half and apply it in two passes instead of one. Make the two applications in a criss-cross direction.
Example: Apply half of the fertilizer going north & south, then apply the second half going east & west. This reduces the chances of "skunk stripes" as well as burned-out or missed spots.
Research has shown that turfgrass prefers a fertilizer analysis (or ratio) of 4-1-2 or 3-1-2. This would translate into a fertilizer product that might have 24-6-12 or 18-6-12 on the label, with nitrogen making up the highest percentage by weight.
Less expensive fertilizers contain all 'quick release' nitrogen which becomes soluble as soon as it is watered into the lawn. Quick release nitrogen has a short duration and applications aren't usually effective for more than 4 weeks.
Slow-release nitrogen is generally more expensive and comes in many forms. The slow release part of the nitrogen is listed on the label as "WIN" or "Water Insoluble Nitrogen."
Organic fertilizers such as Milorganite have very slow release nitrogen since it requires microbial activity in the soil to make the nitrogen available to plants. Always read and follow label directions on all fertilizer products.