In the below video, UNH Cooperative Extension field specialist, Margaret Hagen, describes the process of renovating a lawn.
Hello my name is Margaret Hagen and I'm a field specialist for UNH Cooperative Extension. Today we're going to talk about renovating your lawn. Renovating a lawn involves restoring a deteriorating turf grass area to healthy dense lawn. A healthy established lawn will generally be able to out-compete many weeds, withstand a certain amount of damage from insects disease, and also cope with drought. When your lawn is in poor condition because of poorly adapted grasses thinning turf, weed problems, insect or disease damage, or excessive thatch it's time to renovate. Most of the problems mentioned here can be corrected by simply selecting the right seed, renovating and then improving your maintenance practices.
Renovating a lawn is best done between mid-august and mid-september when there is no competition from annual weeds like crabgrass. The soil is still warm, daytime temperatures are cooler, and fall rains are generally very common. Doing your seeding between mid-august and mid-september will ensure that your seedlings have time to get fully established before cold weather arrives.
The first thing to do is get a soil test done. For a reasonable fee UNH Cooperative Extension will analyze your soil. The results will contain your soil pH and certain nutrient levels from which lime and fertilizer recommendations can be made for your lawn. The next step is to control weeds. If there are a small number you can probably just pull them. If there are too many to pull you may need to apply a weed killer or herbicide. If your weeds are primarily broad leaves, like dandelions, violets, or plantain, you will need to apply a broadleaf herbicide. If more than fifty percent of the lawn is weeds you may want to kill all the vegetation with a non-selective herbicide like glyphosate. In the situation here the lawn is about forty percent crabgrass so the only weed control necessary was to mow the grass to a three-quarter inch height and then bag and dispose of the crab grass seed heads.
If the soil is dry, as is often the case at this time of the year, soak the soil to a depth of four to six inches and then allow the surface to dry for one or two days before proceeding. If the thatch layer of decomposing organic matter is more than one inch thick remove it at this time with a dethatcher. Dethatchers are also often called power rakes or vertical mowers.
They have a series of vertical blades or tines which rotate at a horizontal shaft to remove surface debris and thatch. You may need to make several passes to expose a little bit of soil for seeding if the fast layer is less than an inch thick. A core cultivator or aerator can be used to create a seed germination environment that will ensure good contact between the seed and soil. Aerators remove plugs of soil from the lawn area to alleviate soil compaction and prepare a partial seedbed. Your aeration should consist of five to eight passes over the area to be seeded. At this point you can apply lime and fertilizer according to your soil test recommendations.
The next thing to do is to drag the area with a large doormat or a section of chain-link fence this will mechanically break up the aerated plugs and work the lime and fertilizer into the seedbed. A turf type disk seeder, or a slice seeder as it is also known, is the best tool for seeding. This machine cuts the seed directly into the soil ensuring firm contact between seeds and soil for good germination. Achieve uniformity by seeding in opposite directions after setting the spreader to deliver at one-half a desired rate. When no disc type seeder is available uniformly broadcast the seed using a hand or push spreader.
Following seeding, rake or drag the area again, where needed, into the seed bed and cover the seed with a light layer of soil. Next firm the seed into the soil by lightly rolling the area and apply a light straw application if there is little existing grass. Follow this up by watering. You will need to water lightly infrequently two to three times each day to keep the seedbed damp during germination and establishment. Germination can take three weeks or more depending on your seed mix. When about sixty percent of your new grass has reached a height of two to three inches it is time to start mowing. Keep in mind that good management is necessary to both get and keep a healthy lawn. Proper liming and fertilization, mowing, irrigation, and aeration practices must be followed continuously to ensure the improvement of your lawn. After all, it's a lot of work to renovate so you'll definitely want to do all you can to keep that beautifully renovated lawn healthy.