Renovating the Home Lawn
By Tony Koski, Turfgrass Specialist, Colorado State University Department
of Horticulture and Landscape Architecture
WHAT is lawn "renovation"?
Lawn renovation involves the killing of existing turf and replacement with new grass
without the tilling or changing of grade normally used for the establishment of a new
lawn. "Partial" lawn renovation may also involve the following:
- Introduction of new/improved varieties of the same turfgrass species into an existing,
living lawn. Example: new bluegrass varieties into an existing bluegrass lawn
- Introduction of similar-looking species into an existing, living lawn. Example:
the introduction of perennial ryegrass into a bluegrass lawn
WHY renovate your lawn?
- Your lawn consists of a species or variety that is frequently attacked by disease or
insects, causing it to thin out.
- The landscape has become increasingly shady over time, causing the original lawn to
become thin and unhealthy.
- The lawn was severely injured or totally killed by a disease, insects, or drought, or
- You want to completely convert from one turf species to another.
WHEN can you renovate a lawn?
- Cool-season grasses (bluegrass, ryegrass, fescues) can be seeded anytime from March
through September, with the optimal time being mid-August to mid-September along the Front
Range and on the Western Slope.
- Warm-season grasses (buffalograss, blue grama) can be seeded from April through July;
seeding after July is not recommended.
- At high elevations (greater than 7000 feet) warm-season grasses should not be used and
cool-season grasses can be seeded in the spring as soon as temperatures begin to warm.
- Late fall seedings are not recommended, as any young seedling will probably be
winterkilled; it is better to wait until the following spring to practice lawn renovation.
HOW do you renovate a lawn?
- Kill any existing grass and weeds using a non-selective herbicide, the most effective
products being those that contain glyphosate.
- Glyphosate is only effective on actively growing grass and weeds, so the area should be
irrigated occasionally to encourage plant growth before applying glyphosate.
- Wait 10 days following glyphosate application, watering occasionally, to ensure that all
vegetation has been killed.
- When the existing vegetation has been killed, mow the site down to about ½ inch and
remove the debris by raking or using the bagging unit on your mower.
- If there is an existing thatch layer (a matted layer of organic matter on the soil
surface) deeper than 1 inch, it should be removed from the lawn (a sod cutter works best).
- A thatch layer less than 1 inch in depth need not be removed, but the soil must be made
visible for seeding purposes:
- Core cultivation will provide an excellent seed germination environment; holes should be
1 to 3 inches deep and 2 inches apart in all directions.
- A power rake, set deep enough to expose the soil, can be run over the lawn in two
different directions; remove loose debris by raking or with mower and bagging unit.
- Seeding can be done once the soil has been made visible to allow for good seed soil
- Seed at the recommended rate with a drop spreader in two directions and follow by light
raking to work seed into the soil.
CARE of the new seeding
- A starter fertilizer can be applied at the rate recommended on the label.
- The area should be irrigated to maintain a constantly moist (but not saturated) soil.
- The presence of dead turf and a thatch layer will reduce the need for frequent
irrigation: check moisture levels in the underlying soil to prevent excessive irrigation.
- Grass will germinate and grow most obviously in aerifcation holes or slits made by the
- Begin mowing the lawn when it has grown to about 2½ inches in height.
- Keep traffic (children and pets) off of the lawn as much as possible if all old turf had
been removed prior to seeding; more traffic can be tolerated if the old lawn vegetation
has been left in place prior to seeding.
DON'T do this!
- Don;t simply scatter seed on an unprepared lawn surface.
- Don't buy "cheap" (low quality, weedy) seed.
- Don't use preemergent herbicides before, during or after the renovation process.
- After the initial use of glyphosate to kill the existing lawn and weeds, don't spray
herbicides for the control of visible weeds until the lawn has been mowed 4 to 5 times.
- Don't overfertilize to make the new lawn grow faster.
- Don't let the new grass get too tall before mowing.
WHAT should be seeded into the lawn?
- If the old lawn grass is still alive, the overseeded grass should be somewhat similar in
appearance to the existing species.
|* seeding ryegrass into bluegrass is OK
|* seeding fine fescue into bluegrass is OK
|* DON'T seed tall fescue into bluegrass
|* DON'T seed a warm-season grass into a cool-season grass
|* DON'T seed a cool-season grass into a warm-season grass
- When the old lawn has been killed, use the best adapted grass for the situation; contact
your County Extension Office for advice on species and variety selection
- Purchase seed that shows, on the seed label, that it contains 0% weed seed.
HOW MUCH seed should be used?
Grass species should be seeded at the following rates:
- Kentucky bluegrass 3 to 4 pounds/1000 square
- Perennial ryegrass 7
pounds/1000 square feet
- Turf-type tall fescue 7 pounds/1000 square
- Fine fescues
5 pounds/1000 square feet
3 to 5 pounds/1000 square feet
What about using SOD instead of seed?
- Sod is best used for establishing new lawns, but can be used for renovation if existing
vegetation is removed and the undery8ing soil is core cultivated (aerated) prior to laying
- Sod should not be laid on an existing lawn or where there is a thatch layer.
- Sod should not be laid on heavily compacted soil.
- Successful sodding requires good soil-to-sod contact, which results in better sod
- Decide if the lawn requires total renovation (killing with glyphosate) or only
- Determine what species and /or varieties will be used for seeding
- Apply glyphosate to actively growing grass and weeds 2 weeks prior to the target seeding
- If a thick thatch layer is present, remove with a sod cutter
- If thatchl ayer is not a problem, now dead lawn vegetation down to about ½ to ¾ inch
and remove all loose vegetation
- Core cultivate (aerate) the lawn heavily, so that holes are approximately 2 inches apart
and 1 to 3 inches deep; OR run a power rake over the lawn in at least 2 different
directions to make soil visible for seeding
- Use a drop seeder to apply seed at the recommended rate, going in two different
- Rake the seeded surface, or run over thel awn with a power rake
- Apply a starter fertilizer at the recommended rate
- Irrigate to keep the surface uniformly moist, but not saturated
- Keep traffic to a minimum on the newly seeded lawn
- Avoid the use of herbicides once the lawn has been seeded, and until it has been mowed 4
to 5 times
- Begin mowing the new lawn once the grass has grown to about 2½ inches in height
Photograph courtesy of Judy Sedbrook
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