Renovate Your Lawn by Overseeding Grass in the Fall
Having a five star lawn in Nashville requires dedication. Our soils are not always in the greatest condition and are frequently not much more than heavy clay and rock. Our climate can be finicky too. We’re in a “transition zone” where we don’t have perfect conditions for one type of turfgrass all year. Our summers are too hot and dry for cool season grasses like Fescue to thrive unless you have an irrigation system and our winters cause warm season grasses to go dormant.
I personally love the winter look of a dormant Zoysia or Bermuda lawn as long as it’s weed free, but most folks want a green lawn all year long. Because of our challenging conditions, the best strategy for growing cool season grass in Middle Tennessee is to renovate the lawn through core aeration and overseeding in the fall each year. The overseeding process will ensure a high quality Fescue lawn.
Overseeding grass is when you apply grass seed to an already established lawn. Before beginning overseeding have your lawn core aerated. Core aeration is one of the best things you can do for your lawn and is ideal for preparing the lawn for overseeding. It mechanically removes small plugs of thatch and soil from the lawn to improve natural soil aeration and increases the penetration of air, water, and nutrients into the root zone of your lawn Core aeration also relieves soil compaction and stimulates new growth. You can rent an aerator and do it yourself, but they are heavy machines that can be tough to handle.
If you have an invisible fence for the family dog, it should be located and marked to avoid damaging it with the aerator. The aerator will find and break the invisible fence wire which is usually buried in the top inch of soil or sometimes just lying on the soil surface hiding in the grass. You may want to call a professional service like Perfect World Landscapes, LLC to handle your lawn renovation. We take special precautions and flag all invisible fencing, irrigation heads, and valve boxes to help avoid damaging them with the aerator.
Fall is the best time of year for core aeration and overseeding. You can get good results in spring but the grass will have a better root system established to help handle the stresses that summer brings if overseeding if done in the fall, .
Always Start With the Soil!
Before beginning the lawn renovation you is is a good idea to have a soil analysis done to determine the soil pH and nutrient levels. The UT Extension Soil, Plant and Pest Center is a great resource for this service as well as many other services for lawn, landscape and garden. (Soil Testing at UT Soil, Plant and Pest Center) If the pH and nutrient levels are not ideal for turfgrass the results will show it. Soil pH is a measure of the acidity or alkalinity of the soil with a scale of 0 to 14.
The neutral point or balance for soil pH would be 7. Soil pH is important because it affects the availability of nutrients to plants and the activity of soil microorganisms. The ideal pH for most grass types is 6.5 to 7.0. If the soil tests indicate too much acidity, then you would need to add lime to increase the alkalinity to reach your target pH. If your soil test indicates too much alkalinity, then you would add sulfur to increase soil acidity to reach your target pH.
Your soil test results will provide you with details on adjusting your soil pH to the level needed for anything you are trying to grow in that location.
Diversify Your Grass When Overseeding
Use a blend of seed with several different varieties for a strong stand of grass when overseeding. The greater the variety of grass seed the lawn has growing the better. Diversity creates a stronger, more disease resistant lawn. Most Fescue seed available is a type of Tall Fescue. You will see popular brands such as Rebels or Southern Gold. Each of those usually has several different varieties of Fescue seed blended together.
Tall Fescue is a bunching grass with broader leaves with a variety of name brands available. There are also Fine Fescues which have smaller, more narrow leaves and include varieties like ‘Chewings’ or ‘Creeping Red’. ‘Creeping Red’ Fescue is a pretty good selection for shady lawn areas, but in my opinion there’s no magic turfgrass that will thrive in shade, at least I’ve not found one yet. Sometimes it is better to create garden beds in shady areas rather than to try to grow a lawn where the conditions are not ideal.
Annual Rye grass is a great choice for a temporary lawn. Annual Rye will grow through the cool season and into the spring then eventually die out when temperatures warm up. Perennial Rye is sometimes used to overseed a dormant warm season lawn to provide green color in the winter. Perennial Rye goes dormant during the warmer months and returns when temperatures cool off. Rye grass grows quickly so you may end up needing to mow your lawn in the winter.
Before purchasing grass seed check the back of the bag for its content. Look for the inert material and weed seed percentages and compare it to other bags of grass seed to find the one with the least amount of inert matter and weed seeds. The label also contains the varieties of seeds the bag so you can adjust your purchase according to what your lawn needs. Measure are of your lawn so you will know how many pounds of seed you need for your situation.
Other Overseeding Considerations
Before you begin your lawn renovation, be sure to mow the lawn a little shorter than usual. Fescue lawns should normally be maintained at 3-4” in height. I like to take a hard rake to my lawn before aerating and seeding to maximize soil contact. Poor soil contact results in lower germination rates.
Your existing grass will also benefit from the starter fertilizer so it will grow quickly while the new seed is waiting to grow. You should try not to mow your lawn after it’s been overseeded until the new grass has germinated and reached 3-4″ in height.
If you are using a grass spreader the most common types to consider are drop spreaders and broadcast spreaders. A drop spreader drops the grass seed directly underneath the bin which allows you to easily control the spread of the seeds on the lawn. Drop spreaders are good for seeding areas around garden beds without accidentally spraying seed into the garden.
Broadcast spreaders cast the grass seed out in a radius around the spreader. These spreaders should have an adjustable guard to prevent casting seed into garden beds. It is very easy to miss areas of your lawn with either spreader so split the grass seed into two batches before you start. When you apply the seed – apply it in two directions to ensure complete coverage of your lawn. Do the same if you’re using a slit-seeder to avoid having tiny rows of grass.
The newly overseeded lawn will need to be kept moist! This may mean lightly misting or watering 2 or three times a day to keep the soil moisture levels ideal for germination and new growth. For an established lawn, an inch of water per week is a good guideline to follow.
Buy a rain gauge or place a cylindrical vessel in various locations around the lawn. Keep the rain gauge away from trees and other obstructions so that it may catch rain or water from the sprinklers to see how long you need to water to attain your goal. A drinking glass or empty can will work just fine. While the accuracy of this method isn’t perfect, it is much better than a guess.
Overseeding your lawn in the fall will provide you with a beautiful lawn that is lush, thick, and very green!