by Roch Gaussion, UNL Turfgrass Specialist and Sarah Browning, Extension Educator
Fall is still the most important time to fertilize cool-season turfgrass. Fall fertilization helps promote recovery, builds roots, and increases sugar reserves going into winter. Key decisions to make in this process include choosing a quality fertilizer and applying the correct amount to your lawn.
Nitrogen, which helps provide nice green color, is the key element when fertilizing lawns. When looking at the fertilizer bag, the three numbers represent nitrogen, phosphorus, and potassium, in that order. Phosphorus is generally not suggested in significant amounts unless a soil test has shown a deficiency or when seeding a new lawn. Potassium is used for hardiness of the plant, however, and is commonly found in winterizer fertilizers sold in fall.
Understanding the Fertilizer Label
Look on the fertilizer package, usually on the back, for the guaranteed analysis. This section tells more about the nitrogen and other nutrients in the package. Look for controlled-release nitrogen in the product. Controlled-release nitrogen, often referred to as slow-release or perhaps extended feeding on the package, will release smaller amounts to the grass over a longer period of time. This leads to more uniform growth.
Examples of controlled-release nitrogen to look for on the label include sulfur-coated urea, ureaform, coated urea, IBDU, and activated sewage sludge. Also look for water insoluble nitrogen, or WIN. These are all examples of good fertilizer sources for use on lawns. Although more costly, controlled or slow release nitrogen fertilizers are highly suggested for lawn use.
If a fertilizer is 20 percent nitrogen, it takes five pounds of fertilizer to supply this one pound. Fertilizer labels often have suggested setting guides and also indications on the lawn coverage the bag will provide.
Whether fertilizing once, twice, three times or more a season, early September is a key time. If the lawn is dry, fertilize right after a rain or irrigate ahead of time for the best results.
Current Recommendations for Fertilizer Applications
Newly seeded areas: Starter fertilizer with higher levels of P2O5 should be applied at or slightly after seeding. A second application of starter fertilizer should then be applied 4 weeks after emergence or mid-October (whichever occurs first).
Newer turf areas (<10 years old) or thin turf: New stands of turf require more fertilizer than older turf areas. Additionally, turf areas that are thin or were damaged by a pest will also benefit from additional fall N to accelerate recovery prior to winter. For these sites apply a balanced (50% soluble and 50% slow-release) nitrogen fertilizer in late-August to early-September. Then make a follow-up application of a quick release fertilizer in mid-October. Again, aim to apply 0.5 to 1.0 lbs N per 1000 ft2 or buy a fertilizer with your spreader setting on the bag.•
Established turf (10+ years old): One application of a balanced released nitrogen source in mid-September. Look for a fertilizer product with 30 to 50% of the total nitrogen as quick-release/soluble nitrogen. This will provide even release during the fall. Aim to apply 0.5 to 1.0 lbs N per 1000 ft2. If unable to calibrate your spreader, then buy a fertilizer with spreader settings for your fertilizer spreader on the bag
This resource was updated September 14, 2021. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)
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