Tall fescue is one of the most popular turf grasses in the transition zone due to its ability to form a great looking lawn, while exhibiting better heat and drought resistance than other cool season grasses. However, unlike other grasses like Kentucky Bluegrass, tall fescue does not spread on its own. Overseeding is a great way to make up for summer losses and increase lawn density in fescue lawns. It is also a great way to introduce new cultivars into your existing genetic base, which can help with disease resistance.
If your existing lawn has 50% or less coverage, you may want to consider a complete renovation instead.
What is overseeding?
Overseeding is the process of spreading seed “on top” of your existing lawn to increase density. As with all seeding projects, success depends upon 3 factors:
1. Seed to soil contact
In order for grass to successfully establish, the seed must be in direct contact with the soil so that the roots may grow into the soil and extract nutrients. Seed that sits on top of thatch or dead grass has a poor chance of establishment.
Fescue seed germinate best when temperatures outside hover between 78-85 degrees. Within this range, fescue germination will take place in 4-5 days. At temperatures in the low 70s/high 60s, fescue germination may take up to 2 weeks.
After seed has been applied and watered, it must be kept continuously moist until germination. Allowing the seed to dry can result in a complete loss. Fescue seed must be watered 3-4 times a day for 15 minutes at a time for the first 7 days. The goal is to keep the seed moist, not to soak the soil. After the first week, the frequency of watering should be gradually reduced and the quantity of water applied at each watering gradually increased.
When should lawns be overseeded?
Fescue lawns North of the Mason-Dixon line should be overseeded mid-August. Fescue lawns in the transition zone should be overseeded around Labor Day. This timing gives the new grass the time it needs to establish so it can survive the following summer.
Spring is a very bad time to overseed lawns due to weed pressure and the limited time available to the grass to establish before the summer heat. Seeding projects in the spring generally result in a weedy mess and wasted time and money.
Preparing for overseeding
Having everything ready when the time comes can make the difference between success and failure. You will need:
- The square footage of your lawn. Tools such as this can be of great help.
- Seed. Fescue should be overseeded with 4-5 lbs of seed per thousand square feet as determined above.
- If you do not have an irrigation system, you will need hoses, a multi-zone controller and impact sprinklers.
- A broadcast spreader.
- Starter fertilizer
- A push mower. If you have a riding mower, it may be too rough to use on the new seedlings.
Overseeding the lawn
In order to give the new seed the best chance to establish, the existing grass must be cut as low as possible. At the same time, since we don’t want to kill the existing grass, this process must take place gradually. Beginning two weeks before your target seeding date, start mowing your grass every 3-4 days lowering your cutting height each time. The final cut should take place on the day of seeding at your mower’s lowest cut setting.
- Remove all clipping from the lawn. Use a rake to remove as much of the thatch and dead grass as possible. Remember, we need good seed to soil contact.
- Using the broadcast spreader, spread the seed at a rate of 4-5 lbs per thousand square feet slightly overlapping each pass. Do not over-apply – grass that is planted too dense is unable to develop properly and looks like doll hair.
- Using the broadcast spreader, apply the starter fertilizer at the rate indicated on the bag.
- You are now ready to water. Program your controller to water each zone 3-4 times a day for 15 minutes.(No sprinkler system? A Orbit 4 zone watering system may come in handy)
Fescue germination should take place in 4-5 days and the seed should be kept moist throughout the process. Mow the grass 14 days after seeding date and maintain the lawn at 3.5″ throughout fall to encourage lateral growth.
With a refreshed, thick lawn, the grass will always be greener on your side.