August 1995 - Volume II, Issue 8

Fall Turf Fertilization for Cool Season Grasses

David M. Kopec, Extension Turfgrass Specialist

Fall is the best time to fertilize cool season turfgrasses at the higher elevations where they are grown year round. This is because the return of cooler day and night time temperatures and the shorter day lengths trigger optimum growth and new roots. Turfgrasses that make this response include Kentucky bluegrass (KBG), perennial ryegrass, tall fescue, and the fine leaf fescues. The rule of thumb is to apply about two thirds of the yearly nitrogen requirement (in two applications in the fall) and apply the last one third in the following spring. For the two fall applications, you want to apply about 65% of the total fall -N- in the first application, and the remaining 35% in the second fall application. The second application is sometimes referred to as the "late fall season application", which should be applied before the grass goes semi-dormant when the ground surface begins to freeze. The total fall application of nitrogen should be between 1.75-2.5 lbs. of -N- per 1000 ft2. Here are location guidelines for fall fertilization of year round cool season grasses for Arizona.

Location 1st Appl. Amount 2nd Appl. Amount

Flagstaff Sept 10 1.5 lb -N- Oct 10 0.75 lb -N-

Payson/Showlow Sept 20 1.5 lb -N- Oct 25 0.75-1.0 lb -N-

Kingman Sept 20 1.5 lb -N- Nov 5 0.75-1.0 lb -N-

Winslow Sept 30 1.5 lb -N- Nov 10 0.75-1.0 lb -N-

Window Rock Sept 30 1.5 lb -N- Oct 15 0.75 lb -N-

Cochise Cty Oct 5 1.5 lb -N- Nov 5 0.75 lb -N-

Tall Fescue Establishment in the Low Desert for Year Round Turf

Tall fescue can be used in small areas which are either in full sun or moderate shade. The BEST time to establish tall fescue is in the early fall in Tucson and Phoenix, late summer in Cochise county and the Kingman and Payson type areas. Fall seeded tall fescue does extremely well compared to spring planted fall fescue. The biggest mistakes made when establishing tall fescue are (1) seed bed preparation/vegetation removal and (2) following recommended seed rates. Here is the correct format to follow.

1. Get rid of any existing bermudagrass if it was growing previously. Spray the (well growing, irrigated and well fertilized) bermuda with Round-up as a 3-5% solution. Spray during the middle of the day and don't wash it off. Irrigate normally two days later. Repeat one week later on any areas that are still green.

2. Prepare a seed bed by verticutting to 1/2 inch in the soil. Verticut the soil/dead turf in 4 directions.

3. Seed tall fescue at 8.0 lbs. of seed in 1000 ft2. Seed at 4.0 lbs. in each of two directions and you will have good seed distribution. Rake the seed in the ground, and/or cover the previous dead turf with 1/4-3/8 inch of composted steer manure. Water three times daily with light amounts of water in order to keep the seed bed moist. The fescue will emerge in 10-14 days. It is a little slower than ryegrass to emerge. Don't panic, keep it moist, but not flooded.

4. Mow the fescue at a slow ground speed with a sharp rotary lawn mower to 2.5 inches when the grass is 3.0 inches high. At this point fertilize the lawn with 1.0 lb. of -N- per 1000 ft2 from a complete fertilizer (has N-P-K) in a ratio form of 3-2-1, 4-2-1, or 1-1-1. Irrigate once every other day with 3/8 inch of water after the fertilizer has been irrigated in well. Adjust the irrigation accordingly to weather and soil conditions. Mow to 2.5 inches every time the tall fescue reaches 3.0 inches in height. This is important and makes the grass produce more shoots on its own.

Do not plant more than 8 lbs. of turf-type tall fescue seed per 1000 ft. The grass will not mature enough and will go through periods of die back in both the winter, spring, and worst of all, the next summer.

Tall fescue varieties that have the beneficial endophyte fungus are labelled as "endophyte enhanced seed." This is good for a lawn, but not for forage. So don't use endophyte enhanced seed for grazing, hay or green-chop.

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