Overseeding Newly Seeded Lawn

ultravista

LawnSite Member
Atlanta Georgia - four weeks ago I seeded a large backyard area with Pennington Smart Seed Sun and Shade Fescue blend. The area was previously bare and was tilled before seeding. After seeding and applying starter fertilizer, I laid down wheat straw to help with moisture retention. Watering twice a day, the see germinated quickly.

The grass seed germinated in 7-10 days. I mowed for the first time today, four weeks later, when the grass height was greater than 5 inches. The deck was set to 3.5 inches.

There are plenty of bare spots, spots with little or no grass growing. Since I laid wheat straw down, there is a stark contrast between the green of the seedings and the yellow of the straw. Bare spots are highly visible.

I would like to overseed and need advice. When should I overseed, how much seed should I use, and what can I do about the larger (dinner plate sized) bare spots.

Some posts I've read recommend a double seeing for establishing new lawns waiting a few weeks before applying the second seed broadcast.

It is starting to warm-up here in Georgia. I would like to cover up the bare spots and have a lush green back yard. I have 20 pounds of the Pennington Smart Seed in an unopened bag.

Suggestions?
 

Delmarva Keith

LawnSite Senior Member
Best time to seed cool season grass like fescue is late Summer / early Fall. If what you planted is in full sun, when it gets hot in Atlanta the young roots usually still too close to the soil surface can denature, i.e., cook like an egg. The process isn’t reversible so when that happens the grass dies.

You can try overseeding and keeping it moist, but between the heat and fungus pressure on moist, new grass, it might not work out. If it gets afternoon shade it may do better.

Plan for a complete overseed in September after the heat breaks and odds are it will look great next Spring.
 

Valk

LawnSite Platinum Member
Location
KS
Spring seeding is BY FAR the 2nd best time to reseed compared to late-Aug/early-Sept like said above. I tell folks that yeah, it will come up...but the chances of Spring seeding still being there come late Aug after Summer's heat is pretty low. Now, if they are wanting to control erosion, then Spring seeding is semi-worthwhile, but only to a degree.
 
OP
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ultravista

LawnSite Member
We are getting warmer here, but not overly hot yet. I did see the backyard to help with erosion. If I understand, planting later, or reseeding later, will be the best bet for the fescue to establish for the following years hot summer months?
 

RigglePLC

LawnSite Fanatic
Location
Grand Rapids MI
I usually suggest seeding cool-season grass in fall about 8 weeks before normal frost dates.
This spring seeding requires you to carefully go over the whole lawn and throw extra seed on dinnerplate size bare spots. Work the seed in as best you can with a rotary hoe.
However, if you feel the need to seed broadcast in the spring (early summer)--fine--the germination is good since the soil temp is high. If you keep the soil moist, it should work. A seed with fungicide is a good idea (Pennington), particularly if your soil can get really warm and wet. Meta laxal or something similar.
Naturally, the hot weather coming soon and likely dry spells, will probably kill the new grass in sunny spots.
Be sure to use a top-quality disease-resistant tall fescue (brown patch)--with 5 percent hardy bluegrass. Rye is not good due to high temps and disease problems.
Probably it is best to follow Coach Bob with his normal plan--use 10 to 12 pounds of seed per thousand, and 25 percent extra seed if you plan to broadcast with minimal soil preparation. Then "mow-in" the seed.
Remember seed loses about 2 percent germination per month in storage--subtract that from the label percentage germination. 85 percent --after two months becomes 81 percent. 10 pounds per thousand then requires 12.3 pounds per thousand. This is 14 to 17 seeds per square inch.



Remember that it is normal for weeds to be a huge problem in spring seedings--particularly crabgrass. If you cannot use Tenacity or mesotrione--be ready with Drive for crabgrass control post-emergent. Be ready with broadleaf weed control after the second mowing.
 
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Valk

LawnSite Platinum Member
Location
KS
Spring seeding is BY FAR the 2nd best time to reseed compared to late-Aug/early-Sept like said above. I tell folks that yeah, it will come up...but the chances of Spring seeding still being there come late Aug after Summer's heat is pretty low. Now, if they are wanting to control erosion, then Spring seeding is semi-worthwhile, but only to a degree.
I poorly worded the bolded part above. I meant to have have inferred that Spring seeding is a distant 2nd best time to grow grass from seed...and that I'm speaking for my region - as Summer's heat can quickly build in as early as late April/early May. Those new & immature roots are not established enough to tolerate how quickly the soil will dry out from these types of higher temps.
Now and having said the above, THIS year's Spring has been quite cool and we've had 5"+ of surplus rain over & above avg. Spring seeding has worked out well so far...but we won't know how well until late August should we have our usual HOT & HUMID Midwest Summer here in the corn-belt.
 

Delmarva Keith

LawnSite Senior Member
We are getting warmer here, but not overly hot yet. I did see the backyard to help with erosion. If I understand, planting later, or reseeding later, will be the best bet for the fescue to establish for the following years hot summer months?

To answer the question directly (as best I know), yes — Spring planting of cool season grass gives you basically baby grass just as hot and fungus prone Summer weather arrives. It almost always mostly dies.

Planting in Fall gives you many growing days in cooler weather before it shuts down for Winter, and many growing days when it wakes up again the following Spring. Summer is the rough season for cool season grass so it has to be as hardy as you can get it going into Summer.
 

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