September is a key month for lawns. Many lawns went dormant in the heat, while others were maintained with constant watering. Fungi and grubs may have added to the concerns. No matter which concerns you have, now is a key time to give your lawns a boost for fall growth and next year’s health.

There are three key areas that demand attention: fertilization, seeding or overseeding, and weed control.

Kansas’ most common turf grasses are bluegrass, tall fescue and perennial ryegrass. For these cool-season grasses, September is the key month to fertilize, with a second application recommended in November. These grasses are entering a fall growth cycle as the days shorten and the cool temperature returns, especially at night.

If you have warm-season grasses, zoysia, Buffalo, or Bermuda; May and June are key application times. Fertilizing now only increases the growth of cool-season weeds.

The key to what to apply is a soil test. These are offered through the Douglas County Extension Office at little or no charge and should be done every 3-5 years. These tests will give you levels of phosphate (P), potassium (K) and a good indicator of your soils level of acidity (Ph). The test will not show you levels of nitrogen (N) as it leaches from the soil yearly, nor will it indicate the presence of insects, diseases, pesticide residue, thatch or other lawn problems.

A general recommendation is to apply 1 to 1 1/2 pounds of actual nitrogen per 1,000 square feet of lawn. The term “actual nitrogen” can be confusing. Fertilizer bags are labeled with the percentages of NPK. A bag labeled 10-10-10 is a balanced fertilizer containing equal parts of the NPK. A bag labeled 24-4-6 is a turfgrass formulation and has 26 percent N, 4 percent P, and 6 percent K. A 20-pound bag of this 26-4-6 mixture contains only 5 pound of actual nitrogen. This is just enough to put 1 pound per 1,000 square feet on a 5,000 square foot area.

Short of having your soil test results in hand, nitrogen is all you should worry about. Kansas generally has ample supplies of potassium and phosphates. New construction or recently turned soils may be the exception. If you don’t need it, why pay for it? The fall applications should also be a quick release (water-soluble) type fertilizer, as opposed to a slow release (water-insoluble) type.

Ideally the spreader you use should be accurately calibrated and the settings for your specific spreader prominently displayed on the bagged product. Neither of these is likely to be the case and you will either under or overfertilize. There are several ways to calibrate a spreader, but a simple method gets you more exercise.

Measure, by weight, the amount needed of the product you purchased for the area you are covering, using the actual nitrogen content, into your spreader. Set the spreader on a low setting and fertilize your area going only one direction. Fertilize that same area again going the other direction. If there is material remaining, and there should be, start again and continue until it is all gone. Avoid the temptation to just turn it up and get the job over with.

Drop spreaders work well for smaller areas and around ponds, concrete or flower beds where you may not want or need to spread fertilizer. Rotary spreaders cover more area quicker but may not be as accurate in distribution rates, especially with wind and uneven terrain. Granular fertilizers are the most common for the homeowner. Liquid fertilizers are best left to professionals.

After the application, clean up any material that landed on concrete or other impervious surface. These will wash directly to the storm sewer. A good watering will bring the chemical down to the roots, but be careful of runoff, especially with dry or clay soils.

Many fertilizer products also contain an herbicide. These are labeled as a “weed and feed.” Your concern now is fertilization, and that is what you want to pay for. However, it does not hurt to use the “weed and feed” product. If you use these, avoid flower beds.

By law, a container of fertilizer must contain an accurate analysis. The grass does not know the difference between a high-profile brand and a local brand.

Organic fertilizers also are available. These include milorganite (activated sewage sludge), processed poultry wastes, fish meal, soybean meal and blood meal. These are all slow-release types with the exception of blood meal, which is quick release. They are more expensive per unit of actual nitrogen.

Next week we will discuss seeding or overseeding and how to rejuvenate the bare spots.