Overseeding, sometimes called reseeding, is the process of distributing grass seed over an existing lawn. According to information provided by Pennington Seed, there are two primary reasons for seeding existing turf in this manner. First, to either rejuvenate a patchy or thinning lawn or to prevent one. Many grass types will thin out as part of their natural maturing process. Your turf may also develop thinning or bare spots due to the stresses of heavy traffic as well as certain diseases or pests. Simply put, if your lawn is receding, consider reseeding.
Purpose of Overseeding a Lawn
Lawn care professionals will frequently use overseeding as a preventative measure. Instead of waiting for the thin areas or bare spots to appear, they will reseed the lawn so that the new grass plants appear before the weak areas are able to develop. Rather than fixing a poor-looking lawn, this proactive approach keeps the turf looking full, green, and healthy.
The second reason for overseeding is to bring up color when warm season grasses go dormant in winter. This is done by seeding the warm season lawn with a cool season grass seed mix that will produce color during those months when the warm season grasses are dormant. It may seem odd to plant cool season grass seed on a warm season lawn but the very conditions that cause the warm season grass to go dormant—milder daytime conditions and cooler nighttime temperatures—will allow the cool season grass to thrive, if only temporarily. The desired result is year-round green color.
How and When to Reseed
So far we’ve looked at what overseeding is and why to do it. Now let’s address when and how. Cool season grasses of the northern regions enter a period of vigorous growth during late summer and early fall. The soil is still warm enough for the seed to germinate and the cooler temperatures, along with moist conditions, stimulate growth. This is the best time to overseed a northern lawn, with spring being the second best.
By comparison, warm season grasses experience their active growth beginning in late spring, which makes that the better time to overseed a thinning lawn or to prevent one. If winter color in a southern lawn is the goal, fall is the time—just as the existing warm season grass is beginning to turn brown and go dormant.
Without proper preparation and execution, one can spend a great deal of money on overseeding and not see great results. In order for grass seed to become grass plants, it must have an opportunity to germinate and thrive. Simply distributing seed, even good seed, over a lawn may not be good enough, especially if the soil is compacted, there is an excessive thatch layer, or both.
Improve Your Lawn With Core Aeration
Grass seed that cannot get into the soil and receive the necessary moisture and nutrients has a good chance of becoming bird food. Spring-Green’s core aeration service disrupts the surface of the lawn and the soil beneath it by extracting plugs of soil and plant material and then depositing them on the lawn’s surface. This process helps loosen compacted soil and break down thatch, allowing water, nutrients and grass seed to penetrate the soil. For this reason, we recommend scheduling core aeration and overseeding in combination.
Proper seed selection is also important. Use a quality seed mix that is well-matched to your growth region as well as to your overseeding objective. One objective may be to thicken an existing lawn without substantially altering the grass type. Another is to augment the turf by introducing additional grass types to it, such as the introduction of cool season grass seed to a warm season lawn in order to enhance winter color.
Watering, feeding, and weed control practices during the weeks following core aeration and overseeding may also vary according to the specific needs of your lawn. Contact your neighborhood lawn care professional at Spring-Green to obtain more information, ask questions, or schedule this service.