University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Choosing a Lawn Fertilizer

April 19, 2001

Fertilizing is an important lawn care practice, and choosing a good fertilizer is a large part of the process. There is no one best fertilizer, but there are some but there are important features to look for when choosing lawn fertilizers this season.

Nitrogen is the nutrient required most by lawns and the main ingredient to consider when choosing lawn fertilizers. Percent nitrogen is always the first of three numbers on the fertilizer bag. For example, a 34-6-6 fertilizer contains 34 percent nitrogen. But the number alone does not tell much on what kind of nitrogen is actually in the product. Controlled-release, or slow-release nitrogen sources are preferred for most applications to lawns. These types of fertilizers offer advantages of more uniform grass growth and low potential for burning. Most will be more expensive than fast-release nitrogen, however.

Look for the guaranteed analysis section on the fertilizer bag, usually found on the back, for a description of what kinds of nitrogen are actually in the product. Look for terms such as slow-release nitrogen, slowly available nitrogen, or water insoluble nitrogen on the label. Specific controlled release materials to look for include ureaform, sulfur-coated urea, or IBDU, among others.

The other type of nitrogen is called fast-release or quick-release. Examples include urea, ammonium nitrate, and ammonium sulfate. These fertilizers produce a quick response but may burn the grass. Try not to use these in large amounts. Quick-release nitrogen is often mixed with controlled-release in commercially available fertilizers to give a good combination of some quick greening but also some extended release.

When applying fertilizer to your lawn this spring, use a rate of one pound of nitrogen per every 1,000 square feet of lawn area. If high percentage nitrogen fertilizer is used, less actual fertilizer is needed to supply this one pound compared to fertilizers with lower percent nitrogen.


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