The following is a brief calendar for the maintenance of both cool- and warm-season grasses. For more in-depth information on these two subjects, I will direct you to the following online extension publications. Turfgrass management calendar: Kentucky bluegrass lawns ((https://store.extension.iastate.edu/product/4383) and Turfgrass calendar: warm-season lawns in Iowa (Turfgrass Calendar: Warm-Season Grasses for Lawns in Iowa).

As you will see, the timing will be very different for cool-season and warm-season turf. Understanding this is the key to managing these two major categories of grass. In turf management, timing is everything. By getting that right, you can properly manage your turf with little effort. Getting it wrong wastes both time and money and can result in disaster.

One of the biggest mistakes is to treat a cool-season grass like a warm-season grass or visa versa. This is often a problem when people move from one region to another and have to manage a completely different type of grass. If you are new to the area, carefully research your new species and its care.

In this publication, I will deal with Kentucky bluegrass lawns in the Midwest and bermudagrass lawns in the south-central region such as Oklahoma City, OK. In both cases, the exact timing of weed germination will vary by your exact location within the region. I would direct you to your local extension service or perhaps a garden store for more specific information on your exact location.

Let’s begin with Kentucky bluegrass in the Midwest. Cool-season grasses are fertilized in spring, late-summer and fall (see “Developing a fertilizer program for turf” in this series). Avoid summer unless it is really necessary. About two weeks before crabgrass germinates, around April 15, a preemergence herbicide should be applied. These can be purchased in combination with fertilizer and this is a very efficient way to apply the two in one application. The fertilizer will generally apply from 0.6 to 0.75 lbs. nitrogen/1000 sq. ft. which will be enough for the first fertilizer application of the season. In late May to early June, apply another application of fertilizer at a rate of approximately 0.75 lbs. N/1000 sq. ft. The goal is to apply around 1.5 lbs. N/1000 sq. ft. total in the spring. No more fertilizer will be needed until around August 15.

If grubs have been a problem in past years, an application of Merit (imidacloprid) in late June to early July as recommended on the label may be necessary. This will control grubs that begin their damage in August. If you miss this application, an organophosphate insecticide can be applied to the feeding grubs in August of September, but you will have to water it in well to get the material down to where the grubs are feeding. Generally, avoid the use of insecticides unless you are sure that they are needed.

The application of fungicides to lawns is generally not recommended. If they become necessary because of a disease outbreak, it will usually be in summer when they are required. For the most part, don’t worry about fungicides unless they are really needed. If diseases become a problem, you may want to get help from a professional lawn care company.

Around August 15, apply fertilizer at a rate of 1 lb. N/1000 sq. ft. to the lawn. Be sure to water it in if there is no rain following the application. Around the end of September, apply another 1 lb. N/1000 sq. ft. This will be a total of around 3.5 lbs. N/1000 sq. ft. for the season, which should be enough on most lawns.

Between August 15 and mid-September is also the right time for any seeding that needs to be done. See “How to prepare a good seed bed before planting grass seed” in this series.

The fall is the best time to treat broadleaf weeds (see “Postemergence weed control for turf” in this series). The application can take place anywhere from late September to late November. I generally try to have it on by October 15. The materials will generally be effective well after the first frost, however, and you can go later if needed. If this is done properly, only one postemergence weed application will be needed each year.

This sounds like a simple program, but if you stick to the right timing and use quality products, this program will yield very satisfactory results.

The maintenance schedule for bermudagrass is even easier. It is a warm-season grass and thrives during summer if it has enough water. It will go dormant from September to late May in the central US and very little is done to it in during the dormancy period. Apply from 0.75 to 1 lb. N/1000 sq. ft. per growing month. The exact amount will vary with soil type and moisture availability. You can adjust the exact monthly amount based on your observation of the condition of the turf during summer.

Crabgrass will likely be a problem. Preemergence herbicides should be applied in spring before soil temperatures reach 55 degrees F. In regions like Oklahoma City, this will be in mid to late March, at least a month earlier than for cool-season lawns in the north. The type of preemergence herbicide to use will vary somewhat by location. Read the label carefully. It would also be a good idea to check with your local extension service to get their recommendation for your particular location. The preemergence herbicide can again be applied in combination with fertilizer to save time. The further south, the longer the germination period for crabgrass and you might need a second application a month later in some locations, particularly in a wet year. If goosegrass is also prevalent in your region, this will complicate things. If this is the case, carefully research the materials available for both crabgrass and goosegrass in your location.

Broadleaf herbicides can be applied in summer, if necessary, but they should not be used when the temperature exceeds 85 degrees F. As was the case with cool-season grasses, it will be better to apply broadleaf controls in fall if possible. There may be some grass sensitivity issues with some broadleaf herbicides, so again, read the label carefully before using them.

Insecticides and fungicides should not be a regular part of the lawn care program unless they are truly needed. In most years, you will likely be able to go without these pesticides.

Unlike cool-season grasses which are seeded in late-summer and early fall, the seeding of warm-season grasses should be timed in the spring. Bermudagrass will do best if it is seeded in May or June so that it has the full summer period to mature and spread.

Nick Christians, University Professor of Horticulture, Emeritus, Iowa State University

books: Nick Christians, University Professor of Horticulture, Emeritus, Iowa State University

books: http://www.amazon.com/Nick-Edward-Christians/e/B001H6SB7A/ref=ntt_dp_epwbk_0

turf blog: http://www.iaturf.blogspot.com/

Fundamentals of Turfgrass Mgt. 5^th ed  http://www.wiley.com/WileyCDA/WileyTitle/productCd-1119204631.html

Web site:  https://www.hort.iastate.edu/directory/nick-christians/

turf blog: http://www.iaturf.blogspot.com/

Fundamentals of Turfgrass Mgt. 5^th ed  http://www.wiley.com/WileyCDA/WileyTitle/productCd-1119204631.html

Web site:  https://www.hort.iastate.edu/directory/nick-christians/

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