For cool-season turfgrass, fall is a time of renewal and recovery from the stresses of summer heat. As the temperatures start to moderate and rainfall increases, the turf plants will start growing new roots and new plants to replace those that were damaged or even killed during the summer. Spring may be the time when other landscape plants start to grow, but fall is the time of regrowth for cool-season turfgrasses with core aeration.
Cool season turfgrasses like Kentucky bluegrass, perennial ryegrass, fine fescue and tall fescue have varying degrees of tolerance to heat and drought:
|Heat Tolerance||Drought Tolerance|
|Fine Fescue||Good||Very Good|
|Kentucky Bluegrass||Good to Poor||Good|
|Tall Fescue||Very Good||Very Good|
These ratings are based on an average summer. If conditions are extreme, the turf will suffer. For example, roots of Kentucky bluegrass will start to die when soil temperature in the top inch of soil will start to die. All these grasses can survive about 28 days without water, but they all will thin out if a drought lasts much longer than 28 days.
Fall Core Aeration
One constant in lawn care is that all lawns will benefit from an annual core aeration. Core aeration is performed by a machine that travels across the lawn and has a series of tines built in that puncture the soil and remove 2 to 3-inch-long plugs or cores of soil and thatch and deposits the them back on the lawn’s surface. This process will open the lawn to provide more air, water and nutrients into the turf root zone. Strengthening the roots is key to having a healthy lawn.
The best time to do core aeration on a a cool-season lawn is in the fall, from mid-August through mid-December. A lawn can also go through aeration in the spring, but the optimum time is in the fall. The roots of cool season turf grow best when soil temperatures are in the range of 60 to 80 degrees. Even if the lawn is aerated before the soil temperatures drop to these favorable levels, the aerification process will be completed to help promote better root growth when the temperatures drop.
Fall Lawn Reseeding
A great time for lawn reseeding is shortly after it has been core has gone through aeration. Grass seed needs to come in contact with soil and receive adequate moisture to remain viable once the germination process begins. A good portion of the seed will end up in the core holes, which ends up being a great place for the seed to germinate. The soil in the core holes will be cooler and remain moist and the seed will have a much better chance of germinating. Soil temperatures for seed germination for the different cool season grasses are:
|Kentucky Bluegrass||59 to 86°|
|Fine Fescue||59 to 77°|
|Perennial Ryegrass||68 to 86°|
|Tall Fescue||68 to 86°|
Even if your area did not have to endure any extreme heat or drought this past summer, having the lawn aerated and reseeded will help ensure an even better lawn next year. One other important part of a fall lawn overseeding program, it needs to be completed early enough for the seed to germinate and sufficiently grow before inclement weather sets in for the winter. In the colder parts of the cool-season areas, try to have the seeding completed by the end of September. If you are in the more southern part of the cool season areas, you have more time, but you should try to have it completed by end of October.
If you are interested in having your lawn core aerated and overseeded this fall, contact your neighborhood lawn care professional at Spring-Green and make arrangements to rejuvenate your lawn this fall.