Late Summer is Time to Rejuvenate Your Lawn

By Marcus Jones
Department of Horticulture
Iowa State University

If your lawn failed to live up to expectations this summer, don’t wait until next spring to take action.  The late summer/early fall season is a great time to rejuvenate your lawn.  It’s important to keep in mind that even the most attractive lawns don’t look that way on their own.  Creating and caring for a beautiful lawn takes time and effort.  Performing a few key maintenance practices now will help get your lawn back in shape and prepare it for next spring and summer.  Controlling perennial weeds, fertilizing, establishing new turf with seed and aeration are basic maintenance practices commonly performed during the next couple of months. 

• Controlling perennial weeds – Annual weeds such as crabgrass and goosegrass die with the first hard frost in the fall.  Weeds with annual lifecycles should be controlled during the spring and early summer months. Perennial broadleaf weeds such as dandelion, ground ivy (creeping Charlie), white clover, and broadleaf plantain are best controlled during the fall months as temperatures cool (Picture 1).  While these weeds may be removed by hand, such control often is temporary as the weeds will regenerate from deep taproots or special creeping stems called stolons.  Broadleaf herbicides provide the best control and may be applied as a spray or be packaged with a granular fertilizer in a "weed-n-feed" type product.  Make sure the purchased product controls the weeds present in your lawn and always apply according to the directions.

• Thicken existing turf with fertilizer – One of the best strategies to control weeds is by having a healthy, thick lawn. However, most lawns struggle to grow during the hot, summer months especially if rainfall is scarce and the lawn is not irrigated.  Many times by the end of summer the turf declines to the point that bare soil is exposed (Picture 2).  Fertilizer can help stimulate the growth of the existing turf and help fill-in the thin spots. Two or three fertilizer applications may be applied during the next couple of months depending on the level of recovery that is required.  Often, the final fertilizer application is made after the grass has stopped growing.  This strategy is known as “late fall fertilization” and will help your lawn develop a stronger root system and green-up faster the following spring.    

• Establish new turf with seed – Sowing seed may be necessary if your lawn has been damaged to the extent that the growth of the turf (even with fertilizer) will not be sufficient to fill-in areas of exposed soil (Picture 3).  Seed germinates readily in late summer/early fall if the seedbed is kept moist.  The type of seed purchased depends on the landscape.  Use Kentucky bluegrass alone or mixed with perennial ryegrass if your lawn receives full sun.  If the lawn receives both sun and shade, use a mixture of Kentucky bluegrass, perennial ryegrass and fine fescue.  Fine fescue should be used alone in areas that receive heavy shade.  Difficult growing areas such as a boulevard or areas surrounded by concrete can be sown primarily with tall fescue mixed with a small amount of Kentucky bluegrass.     

• Aeration – Consider aerating the lawn if extensive seeding is necessary.  Aeration removes cores of soil without disrupting the turf canopy.  Pass over the area at least two times, each in a different direction.  Apply fertilizer and seed to the area and lightly water the area to moisten the soil surface.  Seed will filter into the holes and germinate.  Aerification is also routinely performed during the fall months to loosen soil which has been compacted from heavy traffic and to prevent thatch accumulation. Thatch is a layer of organic debris which forms between the soil surface and turf canopy (Picture 4).  Too much thatch causes many problems, including poor rooting and increased disease activity.

Contacts :
Marcus Jones, Horticulture, (515) 294- 2751,
Richard Jauron, Horticulture, (515) 294-1871,
Cynthia Haynes , Horticulture, (515) 294-4006,
Willy Klein, Extension Communications and External Relations, (515) 294-0662,

Four high resolution photos are available for use with this article:
0911perennialweeds.jpg Caption: Perennial weeds such as dandelion (A), ground ivy (B), white clover (C), and broadleaf plantain (D) are best controlled during the fall as temperatures cool.  Herbicides applied in the fall are readily absorbed and move throughout the weed and into the root system for complete control.
0911baresoil.JPG Caption: Fertilizers will help turf recover that has declined during the summer months.  Fertilizer applications will help stimulate the turf to grow and fill-in areas of exposed soil.
0911preparesoil.JPG Caption: The fall months are the ideal time to establish new turf from seed.  Small areas can be sown by scratching the soil surface with a garden trowel and evenly spreading seed over the area.  Firm the soil with your foot or tamp and lightly water to moisten the soil surface.
0911thatch.jpg Caption: Thatch is an organic layer which forms between the soil surface and turf canopy.  Aerification is routinely performed to remove excessive layers of thatch.