Reseeding Fescue Lawns in Fall

Use these tips to keep fescue healthy in summer heat

Brian Jervis: Ask a Master Gardener   

Monday, August 15, 2016 12:00 am

Q: Every summer some of my fescue dies and I have to reseed. Any way to prevent this? How do I reseed and what seed is the best? G.H., Tulsa

A: Each year at this time issues with repairing the summer’s heat damage to tall fescue lawns

commonly arises. This is because we live in a transition zone of turf grasses, we grow both warm season and cool season grasses and each would prefer to be grown either farther south or farther north.

Fescue grows best at moderate temperatures and prefers spring and fall where it performs ideally. When summer comes, even well-irrigated tall fescue often is beset with both heat damage and a fungus called “brown spot,” causing death of some fescue, which then needs reseeding.

Reseeding of tall fescue may be done in either spring or fall, but fall is by far the best. Spring-seeded fescue usually does not have enough time to establish a mature supporting root system to tolerate the stress of summer, whereas if sown in fall it does. It is recommended that tall fescue ideally be reseeded from mid-September to mid-October.

As far as how to reseed, there are several steps involved. Detailed information is available in the Master Gardener’s office in Tulsa or online.

An important part of this process is selecting the seed. OSU feels that there is no one best fescue seed. They strongly recommend that a blend of three or more fescues be planted, with or without a mix of Kentucky bluegrass. These combinations use the strength of one variety to offset the weaknesses of another.

Steps for reseeding fescue lawns

1. For existing lawns, identify and correct factors causing poor performance. Start with a soil test to see what nutrients and soil acidity corrections may be needed.

2. Make a decision as to what type of seed you wish to plant, purchase beforehand.

3. Buy a “starter” fertilizer, best based on soil test. Use only nutrients needed. Do not use a fertilizer containing phosphorus unless a soil test indicates a need.

4. Remove undesirable grasses and weeds.

5. Loosen the soil by hand or machine and add fertilizer and organic compost as needed. This step is important.

6. Sow the proper amount of seed to get good coverage, avoid excess seeding. More is not better.

7. Irrigate as needed to keep top of soil constantly moist until seedlings are 2 inches tall.

8. After 2 inches in height has been reached, irrigate less often and more deeply.

9. Mow with a sharp-bladed mower when 3 inches tall.

10. If needed, control broadleaved weeds with a 2,4-D type herbicide after third mowing.

To minimize loss of fescue next summer, obtain the Master Gardeners information sheets on lawn care and follow recommendations about watering, fertilization and mowing. Another useful document is OSU fact sheet HLA-6419, “Establishing a Lawn in Oklahoma.”

For readers interested in exploring the performance of fescue varieties determined by OSU, go online and search for “Oklahoma State, Current Report 6602.”

Garden tips

§  Fertilization of warm-season grasses can continue if water is present for growth. Do not fertilize Bermuda or zoysia lawns after the end of August. Do not fertilize fescue lawns until it cools off in September.

§  Establishment of warm-season grasses such as Bermuda and zoysia by sodding or sprigging should be completed by this time to ensure the least risk of winter kill.

§  Mowing heights for cool-season turf grasses should be at 3 inches during hot, dry summer months. Gradually raise mowing height of Bermuda lawns from 1½ to 2 inches.

§  Cucumbers may be bitter this time of year and vines quit producing. This is due to the heat. If you are able to get the vines through the summer, after it cools, they will be fertile again and the taste of the cucumbers will improve.