REJUVENATING TURF AREAS

Last updated 12/1/99

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Rejuvenating Turf Areas After

the Drought of 1999

Zac Reicher and Clark Throssell
Purdue University Turfgrass Specialists

AGRY-99-05
Dec.1, 1999

After the extended heat of July and the continued low moisture conditions from July through at least December 1, many turf areas across the state are thinned or weakened going into winter. Depending on the harshness of winter, it is conceivable that significant winter damage may occur in weakened turf. Following are some options for improving turf stands yet this fall as well as next spring.

Fertilize Now
If you did not apply fertilizer in November, apply now while the grass is still green. Apply 1.5 lbs N/1000 ft² using a fast release N source such as urea. This will encourage the grass to increase density, stay green later in the fall, and green-up earlier next spring. It is extremely important to apply this fertilizer now and/or while the grass plants are still green and temperatures are adequate for photosynthesis (40-50^oF). The nitrogen must be applied while the plants are still green and photosynthesizing in order for it to be taken up and stored in the plant before winter, ready to use as temperatures warm-up next spring when it will be used to encourage root growth. You cannot substitute an early spring fertilization for a late fall fertilization because N applied and taken up by the plant in the spring is used for shoot growth and it may actually limit root growth. Do not apply to dormant (brown) turf during the winter because the fertilizer will not be taken up until spring (if ever).

Seeding
On non-erodable areas, dormant seeding of Kentucky bluegrass, tall fescue or perennial ryegrass can occur at anytime during the winter when the soil is dry enough to prepare a seed bed. Turfgrass seeded at this time will not germinate until soil temperatures warm up next spring. This technique has been successful on relatively flat areas, but should be avoided on sloped areas prone to erosion. To help reduce erosion on moderately sloped sights, consider using hydromulch, straw with a tackifier, or other commercially available erosion control nets or blankets. There is some risk with the quick-germinating perennial ryegrass that it might germinate and start to grow with warm spells during the winter, only to perish with ensuing cold weather. However, this risk might be justified if the turf is very thin and in need of overseeding.

If you can’t dormant seed, seed as early in the spring as possible. As with dormant seeding, disturb the soil with tilling, raking or any process that will help improve seed-to-soil contact. Whether dormant- or spring-seeding, a starter fertilizer is important and it should be applied in the spring shortly after germination when the seedlings can use the fertilizer. Also begin watering lightly as soil temperatures warm to 50^oF and seed starts to germinate. Be careful with any herbicide applications because most will harm seedling growth (see below for more information). Since the dormant- or spring-seeded turf will not develop a good root system until next fall, keep the newly-seeded areas well-watered all summer.

Sodding
Sod can be used successfully during almost any time of the year and is the quickest way to improve a turf in poor condition, plus it is the best establishment method to use on sloped or erodable sites. A risk with sod is that it might desiccate during the winter with prolonged cold temperatures and dry winds. Be sure to water the sod thoroughly immediately after laying and occasionally during the winter if we have an open, windy winter. Proper soil preparation is critical for successful sod establishment, so prepare the soil as you would for seeding. Some root growth will occur during the winter depending on soil temperatures, so apply a starter fertilizer prior to sodding. However, sod laid during the winter will not root significantly until spring, so plan on irrigating the area in spring and throughout most of the summer.

Spring Weed Control
For areas that were seeded late this fall, or will be dormant- or spring-seeded, annual grass control next spring will probably be needed. Drive from BASF is labeled for application within 4 weeks after turf seedling emergence. Drive is effective as a postemergence product but has little preemergence activity. However, Drive also controls a variety of broadleaf weeds. Dimension is also labeled for application within 4 weeks after seedling emergence and will control crabgrass both pre and postemergence. Drive is more effective on larger crabgrass than Dimension, whereas Dimension is more effective on smaller crabgrass than Drive, and its preemergence activity is a plus. Be sure to follow the label restrictions for most effective and safest control.

Fertilize Next Spring and Summer
To help turf areas continue to fill-in during spring and summer, it is important to provide adequate nitrogen. Applications of about 0.75 lbsN/1000 ft² in May, June, and July using mostly slow release N sources should encourage increased density without stimulating too much shoot growth. This program can be used on newly-seeded areas as well as established areas that are thin and in need of recovery. Return to the standard fertilization program when the turf heals satisfactorily, fertilizing primarily in the fall.

Irrigate Next Spring and Summer
To maximize filling-in of the turf next spring and summer, provide adequate moisture to the turf. Generally, a turf may need up to an inch of water per week, preferably in one or two applications. If the weather turns dry, water thoroughly to wet the soil to the depth of the root zone and then don’t water again until areas of the turf turn a slight bluish-gray. This is the first sign of drought stress and the turf should be watered thoroughly the next morning.

More information
Much more information is available on our web page from the following publications:

AY-3: Establishing Lawn Areas From Seed

AY-7: Irrigation Practices for Homelawns

AY-13: Lawn Improvement Programs

AY-20: Seeding a Turf Area in the Spring

AY-22: Fertilizing Established Lawns

AY-25: Purchasing Quality Grass Seed for Your Lawn

AY-27: Maintenance Calendar for Indiana Lawns

AY-28: Establishing a Lawn from Sod

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