Notes (by Nelson Itterly) on a talk by Albert Hirson
St. Louis Master Gardener, University of Missouri Extension
314-439-1711        ahirson@msn.com

General
Cold weather grass grows between 45 - 75 degrees F.
That is between mid March and mid June and between September to mid November
If you fertilize only once, do it in fall at beginning of growing season.
Kentucky fescue 31 is a good cold weather grass.

Mowing
For cold weather grass, set mower for 2.5" - 3.5" blade height and keep blades sharpened.
Never scalp cold weather grass.
Never mow when grass is wet.
For healthy lawn, clippings should be less than 1 inch; don't remove more than 1/3 of the leaf.
Contrary to belief, most thatch is not made up of clippings.
Heavy clippings should be raked.
Bagging is usually not required.

Watering
To determine sprinkler output use shallow cans placed around the yard, then water for 20 minutes.
Measure water and use average.
Lawn should receive 1 1/4 - 1/1/2 " water per week.
Water deep, water infrequently - no more than twice a week early in the morning.

Fertilize
Fertilizers numbers represent "pounds per 100 pounds;" 12-12-12 has 12# of nitrogen per 100# of fertilizer.  A balanced formula is good.  Don't use more than 1# of nitrogen for 1000 square feet of grass.  Grass likes a 3-1-2 ratio.  Fertilize when grass is growing.
If you fertilize once a year, do it in mid-September.
If you fertilize twice a year, do it in mid-May to mid-October.
If you fertilize more often, do it in May, September and October.

(following from U. of Illinois) Burned grass is a drawback of fast release nitrogen fertilizers.
Fertilizing influences grass color, ability to recover from stress, and helps prevent weed invasions and disease. There are important features to consider when choosing lawn fertilizers at the local garden center.
        Nitrogen (N), phosphorus (P), and potassium (K) are the three major nutrients needed by lawns. Nitrogen is the nutrient required most, although too much nitrogen can cause excessive top growth, leading to assorted problems. Percent nitrogen (by weight) is always the first of three numbers on the fertilizer bag, followed by phosphorus and potassium. For example, a 18-6-12 fertilizer contains 18 percent nitrogen. This number is important because it determines how much fertilizer is needed. In most cases, a rate of 1 pound of nitrogen per 1,000 square feet is suggested for each fertilizer application to the lawn. If high percentage nitrogen fertilizers are used, then less actual fertilizer product is needed to supply that one pound compared to fertilizers with low percent nitrogen. Recommended ratios of N-P-K for lawn fertilizers include 3:1:2 or 4:1:2.
        Another important factor in choosing nitrogen fertilizers is what kind of nitrogen is actually in the product. Nitrogen fertilizer may consist of fast-release or controlled-release nitrogen. For lawns, fertilizers containing controlled-release nitrogen sources are suggested for most applications. Check the guaranteed analysis information on the fertilizer label for information on what forms of nitrogen are in the product. Water insoluble nitrogren is slow-release.