Overseeding a KBG lawn - Ask Extension
Hello, we have a 2 year old lawn of Kentucky Bluegrass that was installed as sod. The lawn is in it's 3rd summer and it is showing signs of wear fro...
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Overseeding a KBG lawn #877015
Asked July 12, 2024, 3:41 PM EDT
Hello, we have a 2 year old lawn of Kentucky Bluegrass that was installed as sod. The lawn is in it's 3rd summer and it is showing signs of wear from children and the dog playing on it. We have some areas that are thin/bare, and we are thinking of overseeding this coming fall. Some vendors out there have recommend turf type tall fescue as an excellent overseeding option as it stands up to heat, foot traffic, and can handle shade. However, I have read in the CSU Extension publications that it is not recommended to oversee KBG with TTTF. What is the best seed type recommended for overseeding a KBG lawn? Thank you!
Larimer County Colorado
Expert Response
Hi Taylor,
Thanks for your question - it's a good one. You can overseed turf-type tall fescue into bluegrass, but read on for more info.
First, if your lawn is getting that much traffic, you'll need to increase fertility and irrigation to help the lawn recover. In a way, you're going to treat it more like sports turf than a home lawn. For fertilizer, if you're applying a pound of nitrogen each time you fertilize (this is generally the amount if you're using the correct setting on the bag), you might need 3-4 pounds of N per year. (For reference, sports turf, like football fields, might get 8-12 pounds).
Tell me more about how often you're fertilizing and the type you're using. Are you collecting your lawn clippings?
You may not need to overseed, but simply adjust your cultural care of the lawn - I suspect there's still a lot of grass, but it just needs a fertility boost.
If you do want to overseed, using tall fescue can work, but it does have a slightly wider blade than bluegrass and may not "blend" well. Another species to consider is perennial ryegrass. This is commonly used with bluegrass. It germinates quickly, has excellent traffic tolerance, and is a nice lawn grass.
You can also reseed with bluegrass. Your rates for reseeding are:
TTTF: 4-6 pounds/1000 square feet
KBG: 3-5 pounds/1000 square feet
Perennial rye: 6-8 pounds/1000 square feet
If you do reseed, the easiest way to do it would be to aerate the lawn heavily - use a machine that pulls plugs - and make lots and lots and LOTS AND LOTS of holes. The more holes the better. The lawn should look "bad" when you're done aerating. Then apply your seed. Put half of the needed seed in the hopper of a push-type fertilizer spreader and open the mouth just wide enough to let some seed fall out. Apply in one direction, then add the rest of the seed, and go in the opposite direction. Then rake the entire area to work the seed into the aeration holes. The seed that falls into the holes will germinate best.
Water to keep the seed coat moist - this might be once a day or a couple times per day depending on temperature. Soils are warm in the fall, but seed before September 15 so the seed has time to germinate and harden off before winter.
You can fertilize the lawn the same day you aerate. Keep mowing and watering the rest of the lawn as you normally would.
Thanks for your question - it's a good one. You can overseed turf-type tall fescue into bluegrass, but read on for more info.
First, if your lawn is getting that much traffic, you'll need to increase fertility and irrigation to help the lawn recover. In a way, you're going to treat it more like sports turf than a home lawn. For fertilizer, if you're applying a pound of nitrogen each time you fertilize (this is generally the amount if you're using the correct setting on the bag), you might need 3-4 pounds of N per year. (For reference, sports turf, like football fields, might get 8-12 pounds).
Tell me more about how often you're fertilizing and the type you're using. Are you collecting your lawn clippings?
You may not need to overseed, but simply adjust your cultural care of the lawn - I suspect there's still a lot of grass, but it just needs a fertility boost.
If you do want to overseed, using tall fescue can work, but it does have a slightly wider blade than bluegrass and may not "blend" well. Another species to consider is perennial ryegrass. This is commonly used with bluegrass. It germinates quickly, has excellent traffic tolerance, and is a nice lawn grass.
You can also reseed with bluegrass. Your rates for reseeding are:
TTTF: 4-6 pounds/1000 square feet
KBG: 3-5 pounds/1000 square feet
Perennial rye: 6-8 pounds/1000 square feet
If you do reseed, the easiest way to do it would be to aerate the lawn heavily - use a machine that pulls plugs - and make lots and lots and LOTS AND LOTS of holes. The more holes the better. The lawn should look "bad" when you're done aerating. Then apply your seed. Put half of the needed seed in the hopper of a push-type fertilizer spreader and open the mouth just wide enough to let some seed fall out. Apply in one direction, then add the rest of the seed, and go in the opposite direction. Then rake the entire area to work the seed into the aeration holes. The seed that falls into the holes will germinate best.
Water to keep the seed coat moist - this might be once a day or a couple times per day depending on temperature. Soils are warm in the fall, but seed before September 15 so the seed has time to germinate and harden off before winter.
You can fertilize the lawn the same day you aerate. Keep mowing and watering the rest of the lawn as you normally would.
Thank you for your thorough reply! I was a little late to get the first fertilizer down this year, and so far I've only fertilized once in mid June using an organic fertilizer (7-0-7), putting down about 0.9 lbs of N per 1000 sf. I leave the clippings on the lawn when I mow. So it sounds like I could be using more fertilizer.
As far as irrigation goes, I haven't performed a catch cup test, but I am watering each zone with rotator type sprinklers in a cycle and soak routine for a total runtime of around 50 minutes per zone, 3 times per week. I estimate this comes out to 1 inch per week.
I took some photos, a few of the thinning area, and one of a healthy looking area. These were taken after a particularly hot day during the latest heat wave.
I will keep in mind your overseeding recommendations if that becomes the route we want to take. Thanks!
Hi Taylor,
Unfortunately, I can't open the HEIC photos, but yes, based on your response, fertilizer will absolutely help. You can continue to use organic, but increase the number of times you fertilize. You'll probably want to aim for 3-4 times - perhaps twice in the fall and once in spring? That will help boost the lawn's growth and recovery. Hold off on fertilizing now because it's so hot.
There are organics that have a higher percent of nitrogen in them (7% isn't very high) and also have some quick-release nitrogen. Richlawn is one, as is Scotts Organic. But use what you like best.
Steps to reseeding - wait until mid-to-late August:
1. Mark your sprinkler heads.
2. With an aerator (the machine that pulls plugs), make lots and lots and LOTS AND LOTS of holes over the entire area. If you hire this service out, request they go over the lawn several times. Your goal is 2 x 2 (2 inch deep plugs on 2 inch centers). The more holes the better. Make several passes. If you're able to rent the equipment yourself (or have family/friends do it for you), you can take the time to do good soil prep. [Note: When you aerate, even when not seeding, make lots and lots and LOTS AND LOTS of holes. One pass will do little to improve the overall lawn. It needs to be multiple passes.]
3. With a fertilizer spreader, put the seed in the hopper, with the mouth open just wide enough to let some seed fall out. Seeding rates are as follows: Kentucky bluegrass = 3-5 pounds seed/1000 square feet; tall fescue = 4-6 pounds/1000 square feet; Kentucky bluegrass/perennial ryegrass mix = 6-8 pounds/1000 square feet. It looks like your lawn is mostly bluegrass. Buy high-quality seed - avoid bagged seed from hardware or box stores.
There are two seed companies in Greeley - Pawnee Buttes and Buffalo Brand - or you can see where they sell their seed directly. The grass seed dealers generally sell in bulk and larger quantities.
Note: Because of your pup, you'll need to seed a grass that recovers well from traffic. The top two are Kentucky bluegrass (which is what you currently have/had) or perennial ryegrass or a mix of the two. These are both cool season species.
4. Put half of the seed you need in the hopper of the fertilizer spreader and walk in one direction; put the other half in and go perpendicular to your original path.
5. Rake the seed to work it into the aeration holes. You need to get the seed INTO the aeration holes - seed on the surface will not likely germinate. So drag a rake or work to push the seed into the holes. It's ok for your dog to be on the newly seeded area. We can consider them like a football player - their play will work the seed into the soil, which will result in better soil-seed contact.
6. Water to keep the seed coat moist. Depending on the temperature, you may need to water 2-4 times per day. The better the seed is in the holes, the less you'll need to water. If seed on the top of the soil, then you'll need to increase your watering. This is where your irrigation audit and adjustments come into play. The seed needs to be kept moist during germination. The better you can work the seed into the holes, the better. Soils are cold, so germination will be slow - bluegrass may take three weeks or more.
You can apply a starter fertilizer the same day you seed (example here). The starter fertilizer herbicides are safe for seeding.
If there are parts of the lawn where you can't aerate, use a pitchfork or other device to make holes. A garden weasel tool also does a great job. Rough up the soil, add some seed, and then rough it up again. Work the seed into the soil. Seed will germinate in 7-14 days.
Start mowing as soon as you seed germination - mowing helps the grass "tiller" (creep/spread) and form new roots. Seedlings are pretty tough, but you may want to limit play until the lawn is more established.
Unfortunately, I can't open the HEIC photos, but yes, based on your response, fertilizer will absolutely help. You can continue to use organic, but increase the number of times you fertilize. You'll probably want to aim for 3-4 times - perhaps twice in the fall and once in spring? That will help boost the lawn's growth and recovery. Hold off on fertilizing now because it's so hot.
There are organics that have a higher percent of nitrogen in them (7% isn't very high) and also have some quick-release nitrogen. Richlawn is one, as is Scotts Organic. But use what you like best.
Steps to reseeding - wait until mid-to-late August:
1. Mark your sprinkler heads.
2. With an aerator (the machine that pulls plugs), make lots and lots and LOTS AND LOTS of holes over the entire area. If you hire this service out, request they go over the lawn several times. Your goal is 2 x 2 (2 inch deep plugs on 2 inch centers). The more holes the better. Make several passes. If you're able to rent the equipment yourself (or have family/friends do it for you), you can take the time to do good soil prep. [Note: When you aerate, even when not seeding, make lots and lots and LOTS AND LOTS of holes. One pass will do little to improve the overall lawn. It needs to be multiple passes.]
3. With a fertilizer spreader, put the seed in the hopper, with the mouth open just wide enough to let some seed fall out. Seeding rates are as follows: Kentucky bluegrass = 3-5 pounds seed/1000 square feet; tall fescue = 4-6 pounds/1000 square feet; Kentucky bluegrass/perennial ryegrass mix = 6-8 pounds/1000 square feet. It looks like your lawn is mostly bluegrass. Buy high-quality seed - avoid bagged seed from hardware or box stores.
There are two seed companies in Greeley - Pawnee Buttes and Buffalo Brand - or you can see where they sell their seed directly. The grass seed dealers generally sell in bulk and larger quantities.
Note: Because of your pup, you'll need to seed a grass that recovers well from traffic. The top two are Kentucky bluegrass (which is what you currently have/had) or perennial ryegrass or a mix of the two. These are both cool season species.
4. Put half of the seed you need in the hopper of the fertilizer spreader and walk in one direction; put the other half in and go perpendicular to your original path.
5. Rake the seed to work it into the aeration holes. You need to get the seed INTO the aeration holes - seed on the surface will not likely germinate. So drag a rake or work to push the seed into the holes. It's ok for your dog to be on the newly seeded area. We can consider them like a football player - their play will work the seed into the soil, which will result in better soil-seed contact.
6. Water to keep the seed coat moist. Depending on the temperature, you may need to water 2-4 times per day. The better the seed is in the holes, the less you'll need to water. If seed on the top of the soil, then you'll need to increase your watering. This is where your irrigation audit and adjustments come into play. The seed needs to be kept moist during germination. The better you can work the seed into the holes, the better. Soils are cold, so germination will be slow - bluegrass may take three weeks or more.
You can apply a starter fertilizer the same day you seed (example here). The starter fertilizer herbicides are safe for seeding.
If there are parts of the lawn where you can't aerate, use a pitchfork or other device to make holes. A garden weasel tool also does a great job. Rough up the soil, add some seed, and then rough it up again. Work the seed into the soil. Seed will germinate in 7-14 days.
Start mowing as soon as you seed germination - mowing helps the grass "tiller" (creep/spread) and form new roots. Seedlings are pretty tough, but you may want to limit play until the lawn is more established.
Sorry those HEIC images didn't go through. I've posted them now as JPEGs. Thanks again!
Hi Taylor,
Yes, this is general irrigation coverage and some "hungry" turf. I think focusing on an audit and boosting fertility will help make the lawn more filled in and healthy. Thanks for sending the photos - they were really helpful.
Yes, this is general irrigation coverage and some "hungry" turf. I think focusing on an audit and boosting fertility will help make the lawn more filled in and healthy. Thanks for sending the photos - they were really helpful.
