Dethatch? Aerate and overseed?

[zurfsturfcare]

My yard has almost 3/4 inch of thatch in many spots but also needs overseeded. I would like to aerate it also as it has never been done and is approx 9 years old. Should I dethatch, aerate and overseed. Or do you think aeration in two directions will do enough and follow with overseed?

[Marcos]

My yard has almost 3/4 inch of thatch in many spots but also needs overseeded. I would like to aerate it also as it has never been done and is approx 9 years old. Should I dethatch, aerate and overseed. Or do you think aeration in two directions will do enough and follow with overseed?

Can you upload a digital pic or two of your specific situation?
That may help a great deal in helping to diagnose what to do.

[sdk1959]

Wait till then to overseed but you can dethatch and aerate now.

[Alluring Lawns]

I would'nt recomend aerating and dethatching back to back, that puts a heck of a lot of stress on the lawn, I would do one or the other this spring then maybe the other in the fall. But with your thatch layer I would suggest the dethatching.

[Whitey4]

I would probably suggest a pretty deep dethatching this spring. What kind of turf is it? KBG will spread out again in runners, while tall fescue and Rye won't, as they are clumping grasses.

Will you use a crabgrass pre-emergent? Is there a history of CB? If there is, dethatch, use a CB preventer, then aerate and slit seed in the fall insead... then top dress.

Dethatching will disturb whatever dormant weed seeds are in the turf, just what the doctor ordered for CB germination. I would dethatch pretty deeply soon, use a pre-M CB preventer this spring, treat for any other weeds that may pop up and wait until early fall to aerate and slit seed.

CB germinates at 55 degrees, grass seed at 60. The CB will get a head start on spring over seedings. I refuse... I said refuse to do spring seedings. The results almost always suck. Way too much weed infestation for my standards.... taking for granted you know you can't seed and use a Pre-M in the spring.

[zurfsturfcare]

I would probably suggest a pretty deep dethatching this spring. What kind of turf is it? KBG will spread out again in runners, while tall fescue and Rye won't, as they are clumping grasses.

Will you use a crabgrass pre-emergent? Is there a history of CB? If there is, dethatch, use a CB preventer, then aerate and slit seed in the fall insead... then top dress.

Dethatching will disturb whatever dormant weed seeds are in the turf, just what the doctor ordered for CB germination. I would dethatch pretty deeply soon, use a pre-M CB preventer this spring, treat for any other weeds that may pop up and wait until early fall to aerate and slit seed.

CB germinates at 55 degrees, grass seed at 60. The CB will get a head start on spring over seedings. I refuse... I said refuse to do spring seedings. The results almost always suck. Way too much weed infestation for my standards.... taking for granted you know you can't seed and use a Pre-M in the spring.

thanks for your reply, I think that is what I am going to do, dethatch this weekend, and make a good application of pre-m and aerate and seed in the fall.

[cod8825]

Zurf as others have stated it deepends on what the condition of the lawn. I would only do dethatching if it is non irrigated. If it is an irrigated yard I would feel more comfortable doing both. If you do both put some fertilizer down as well I have found it to help as well

[zurfsturfcare]

thanks for your reply. the lawn does have an irrigation system, it usually isnt used but do you think i could dethatch, aerate, and reseed, with using the irrigation system??

[Smallaxe]

Whitey makes a lot of sense in what he is saying. Good strategy.

I will have to differ with him on germination temperatures of various grasses, however.

CG is a hot weather grass. It germinates , then grows quickly in hot weather.

Cool season grasses will germinate and grow in cooler temperatures. It typically goes dormant when CG takes over.

Nature's way of protecting the soil, whether hot and dry or cool and wet.

Happy St. Patty's Day!!!

[Whitey4]

Whitey makes a lot of sense in what he is saying. Good strategy.

I will have to differ with him on germination temperatures of various grasses, however.

CG is a hot weather grass. It germinates , then grows quickly in hot weather.

Cool season grasses will germinate and grow in cooler temperatures. It typically goes dormant when CG takes over.

Nature's way of protecting the soil, whether hot and dry or cool and wet.

Happy St. Patty's Day!!!

I agree, CB is a hot weather grass, but it does germinate at lower soil temps (55)than cool season grasses(60). Cool season grasses will germinate and have more top growth in cooler spring temps, but CB seeds that have germinated will over power any young grass seedlings as soon as it gets good and warm. Spring seedings look good in the spring, but once it gets warm, CB is the superior competitor. CB is an annual. It has one year to grow, mature and seed. Then it dies. Cool season grasses are annuals. They grow more slowly. The root system is much slower to develop. Young grass seedlings will get over come by the much more aggressive growth habit of an annual weed like CB.

That is why I suggest dethatching in the spring, CB prevention to at least reduce the number of CB seeds that the lawn will produce for next year and other weed controls for this year.

By seeding in the fall, the cool season grasses have much more time to get a root system establishd and will be better able to compete with weeds the following year.

Let me add this, as well: srping seedlings are young, and the summer is the most stressful time of their annual life cycle... in the heat, just when CB wants to grow like crazy. Seeding in the fall gives the grass more time to develop a deeper root system, and are less suseptable to summer burn, and no coincidentally, weed invasion.

[cod8825]

Zurf:

First if you have the money and it is your yard then go for it. I will do some spring seeding myself this year as I am always competing against wild bermuda. Do not do it without irrigation as you will need constant moisture. Last their is a product that I use if I am going to do a spring seeding I will use it is called Tupersan it helps to compete against crabgrass as the seed germinates. Hope this helps

Matt

[Whitey4]

cod, I've done spring seedings, with TWO applications of Tupersan. The stuff is not very effective. But, we can disagree...

Good seed (and using chit seed is a BIG mistake) is expensive. Tupersan might , might have a 50% reduction of CB germination at best. It is alos very expensive. that is a lot of $ to waste on a bad strategy that will not have near the results of a close to perfect lawn that most of us want to achieve.

Do it once... do it right.

I REFUSE to do spring seedings at all, so I am pretty adamant about this as far as my opinion goes. I've tried in before, but to be honest, one time it worked. On my own small front lawn. Less than 2k of turf. EVERY day for three months I hand weeded that lawn for 15 minutes in the morning and 15 minutes in the evening. My lawn is a billboard. It has to be perfect. It is also small. I'll never do a spring seeding again.

[Smallaxe]

I agree, CB is a hot weather grass, but it does germinate at lower soil temps (55)than cool season grasses(60). Cool season grasses will germinate and have more top growth in cooler spring temps, but CB seeds that have germinated will over power any young grass seedlings as soon as it gets good and warm. Spring seedings look good in the spring, but once it gets warm, CB is the superior competitor. CB is an annual. It has one year to grow, mature and seed. Then it dies. Cool season grasses are annuals. They grow more slowly. The root system is much slower to develop. Young grass seedlings will get over come by the much more aggressive growth habit of an annual weed like CB.

That is why I suggest dethatching in the spring, CB prevention to at least reduce the number of CB seeds that the lawn will produce for next year and other weed controls for this year.

By seeding in the fall, the cool season grasses have much more time to get a root system establishd and will be better able to compete with weeds the following year.

Let me add this, as well: srping seedlings are young, and the summer is the most stressful time of their annual life cycle... in the heat, just when CB wants to grow like crazy. Seeding in the fall gives the grass more time to develop a deeper root system, and are less suseptable to summer burn, and no coincidentally, weed invasion.


I couldn't find anything about soil temp for cool season grasses just now, but meanwhile I found this quote:

The seedbed remains firm and moist to
the soil surface which is an excellent environment for germination and growth of new grass seedlings.
Applying this technique for planting into standing cereal stubble is an equally effective variation. The
standing stubble provides protection from the wind, an ideal microclimate for establishment of the grass
seedling. The anchored stubble also reduces the risk of erosion from heavy summer rains. Effective spreading
of chaff and straw prior to seeding are essential for successful use of this technique.

http://www.saskforage.ca/publications/Kentucky%20BG%20Seed%20Production.pdf

The microenvironment of overseeding, in relation to cereal crops. The same principles apply. :)

[cod8825]

cod, I've done spring seedings, with TWO applications of Tupersan. The stuff is not very effective. But, we can disagree...


Do it once... do it right.


Whitey tell me how you really feel about spring seeding. Let me clarify a couple points. I have only done a handful of spring seedings like you 99.9% is fall. Second I will try things out of season on my own yard cause of time restraints and the like. If people have bare spots or yards then for soil erosion and to get started absolutely will I seed in spring. I hope this clarify a few points.

Matt

[Smallaxe]

I can't find anything on actual minimum germination temperature requirements.

Around here we get our lawn grasses to go in April or May depending on the location and weather.
I don't see CG sprouting in lawns until well into June in most cases.

Also I have never witnessed CG sprouting in an oerseeded area prior to the turf seeds.

So where did you get the notion that KBG/Fescue needs 60 degree soil temp to germinate and CG needs only 55?

[Whitey4]

I can't find anything on actual minimum germination temperature requirements.

Around here we get our lawn grasses to go in April or May depending on the location and weather.
I don't see CG sprouting in lawns until well into June in most cases.

Also I have never witnessed CG sprouting in an oerseeded area prior to the turf seeds.

So where did you get the notion that KBG/Fescue needs 60 degree soil temp to germinate and CG needs only 55?

From a seed label. I won't go into the wholesale seed I buy, but it's right there on ant Scotts or Pennington label at the retail level. As for other info sources I might have, I have read reports on this from Cornell, etc and from turf PhD's at my cooperative exchange at seminars and personal conversations.

You missed a major point. Yes, turf will demonsrate earlier top growth than CB, but that does not mean it germinates before CB does. It germinates later... but I'm starting to get tired of repeating myself.

[Whitey4]

I can't find anything on actual minimum germination temperature requirements.

Around here we get our lawn grasses to go in April or May depending on the location and weather.
I don't see CG sprouting in lawns until well into June in most cases.

Also I have never witnessed CG sprouting in an oerseeded area prior to the turf seeds.

So where did you get the notion that KBG/Fescue needs 60 degree soil temp to germinate and CG needs only 55?

Ok, is there ANY ONE number that states what temps are needed for germination? Well, no, but if one wants to extrapolate data, GDD (growing degree days) is a better number to attempt to nail down what soild temps are best, but that differs for different cool season garsses as well.

Some seed will germinate under 60 degrees, but not much... especially if it's KGB. KGB will still germinate, but it will take much longer than rye or fescues, meaning if seeding is done st too low a soil temp, the KGB has no chance. The rye and fescue will outcompete it. The warmer it is, the sooner the KGB will germinate.

After studying reports like this one:

http://crop.scijournals.org/cgi/content/full/45/5/2030

I conclude that cool season grasses, especially mixes of rye, fescues and KGB need a minimum soil temp of 60 degrees F if the germination rates labeled on the seed packaging is to be approached. I suppose one might interpret the data and reach a contradictory conclusion, but if I were inclined and motivated, I would persue that debate.

If one were to sow rye only, acceptable germination rates might be acheived at 55 or perhaps as low as 50 degree soil temps at time of seeding. Still, both germination rates and and time to germination become significantly affected. That opens the window for weed seed germination and weed establishment.

So, there is no one rule, but there is an optimum time to seed, both in time to germination, rate of germination and potential weed invasion. Even using 60 degrees as my guideline may be too low.

In plain english, my contacts at my Cornell coop exchange use the 60 degree number as the minum soil temp for successful germination rates and time to germinate. Yes, one seed out of a hundred might even germinate at 45 degrees, but that is not an econimical use of seed. Good seed is very expensive. It should be used to achieve optimal results.

Rant over.

[Smallaxe]

Good reference, thanks. :)
http://crop.scijournals.org/cgi/content/full/45/5/2030
Two cultivars of each species were germinated at five constant temperatures (8, 12, 16, 20, and 24°C), and germination was recorded one to three times per day. Final germination percentage was little affected by temperature, indicating that the base temperature for germination (Tb) is relatively constant within seed populations. Consequently, germination response to temperature was analyzed by a nonlinear regression method, which combined the thermal time model and the four parameter Weibull function.

10 degrees C is right close to 50 degrees F. ... Fine...

24 Degrees C. is way past 70 degrees F... Even better for everything , including lettuce. :)

Those distinctions only matter when it comes down to whether the KGB is likely to germinate (not green up) b4 the CG.

Whether it agrees with reality I will be researching this spring. I have to clean up a lawn with 'bare spots' that I will dormant seed. When they 'pop' I will add more seed and cover with compost. ...However... My mind will be on the CG germination!!!

If I remember to follow through with this thread I will report back in June or July. ...
... Otherwise remind me.

[Whitey4]

Good reference, thanks. :)
http://crop.scijournals.org/cgi/content/full/45/5/2030
Two cultivars of each species were germinated at five constant temperatures (8, 12, 16, 20, and 24°C), and germination was recorded one to three times per day. Final germination percentage was little affected by temperature, indicating that the base temperature for germination (Tb) is relatively constant within seed populations. Consequently, germination response to temperature was analyzed by a nonlinear regression method, which combined the thermal time model and the four parameter Weibull function.

10 degrees C is right close to 50 degrees F. ... Fine...

24 Degrees C. is way past 70 degrees F... Even better for everything , including lettuce. :)

Those distinctions only matter when it comes down to whether the KGB is likely to germinate (not green up) b4 the CG.

Whether it agrees with reality I will be researching this spring. I have to clean up a lawn with 'bare spots' that I will dormant seed. When they 'pop' I will add more seed and cover with compost. ...However... My mind will be on the CG germination!!!

If I remember to follow through with this thread I will report back in June or July. ...
... Otherwise remind me.

To relate this back to the thread starter's post, it isn't so much about germination temps as it is spring seeding and how those seedlings will eventually have CB breakthrough. Top growth is almost irrelevant IMO as are the germination temps.

My point about spring seeding in an area with a history of CB says that whatever the new grass seedlings do, CB being a much more aggressive grower both in root and top growth development will simply overpower the new grass seedlings. It's an annual. It has to gorw fast, develop roots fast, and go to seed fast. Perenial grasses just can't compete... unless they were planted in the fall to develop further along by the next CB season. That gives them many months of active growth to harden, have denser root development and grab much more sunlight with top growth the following spring. Those things will all make it more difficult for any weed, including CB to develop the following spring.

One thing I would do in the spring is rake out last year's dead CB, and cover that dirt with plasctic when I put down my CB pre-emergent application. If there is a 3X3 patch of dead crabbgrass, that is worth attempting to reseed in the spring. I would not argue against spot seeding in the spring... it's better than bare dirt. That patch will still get run over by CB, but at least it isn't a large amount of seed to waste. For me, renovations are strictly a job for the early fall.

I watched a guy a block away from me last year attempt to DIY a spring lawn. He even tilled it. Stirred up every dormant weed seed that was in the soil. Grass looked pretty good 6 weeks later. (at least for a 30MPH lawn)

Two months after that, it looked like a weed farm. This spring it looks like a weed farm with lots of bare dirt spots. Very little turf survived. Sure, he had some top growth last year. looked good for a short while, but then the weeds had all this open soil to use... no established root system could be grown in time to compete with the weeds. The weeds lost the first battle, but won the war.

I had the same thing happen to me... and the result was a free fall lawn renovation. And that was with two Siduron (Tupersan) applications.