[j4c11]

So we've all read the Fall Nitrogen Blitz, but a lot of that info seems geared towards lawns north of the Mason-Dixon line. Now that there's a few of us growing KBG in VA, NC and TN, the question is what is the best late-fall fertilizer schedule for cool season grasses in this area? I will say that bluegrass continued to grow for me through winter, and I mowed every 2 weeks last winter.

The NC A&T SU Research Farm weather station near me reported the following weather conditions in the past 12 month:

It looks to me like soil temps are ideal for root growth between October and April. So how do we fertilize to best take advantage of these conditions?

 

[g-man]

I researched a bit about this in the past. Universities recommend between 0.25-0.5lb of N/M in the growing months, unless the ground is frozen.

https://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-523/430-523_pdf.pdf

Other skip Dec-January:
https://content.ces.ncsu.edu/tall-fescue-and-kentucky-bluegrass-home-lawn-calendar

I'm sure others will chime in.

 

[social port]

Very interesting post.
I'm not really sure about the best way to interpret that information, but looking at the numbers, it almost seems like we should be moving reno efforts back to October and November. Isn't 55 or so soil temp the sweet spot for germination? And soil temps of 45 degrees don't scare me. Won't cool season grasses still thrive at soil temps of 45? I know that this isn't directly related to fertilization, but it is germane to how we think about our 'cool season' in the transition zone.

 

[LawnNerd]

I think the biggest issue with later seed down dates in the transition zone is sunlight and air temps.

I threw down seed on Aug. 7th this year and the area in question was 100% sunlight. By mid october that area was 90% shade, and 100% shade now from the low angle of the sun behind a neighbors tree. I also started some additional pots in Sept. and those pots are in a very sunny location. They are slowly creeping out of pout. They have been fertilized like the rest of the yard, it's just slow going with the weaker sunlight from the lower angle of the sun. Now that the trees are almost bare, sunlight will increase in my yard, and i'll probably get another good surge of growth.

Another thing is, while soil temps may never freeze, the air certainly does. It's going to be 26 here on Friday and Saturday night. If one where to have seeded KBG on Oct. 1st that KBG would be at most 4 weeks old and most of the seed would be only 2-3 weeks old. I can't imagine these freezing temps would be good for these tender younglings. TTTF would definitly be more mature by then, but i'm uncertain to it's hardiness. Maybe someone else can chime in on this.

It aint easy goings for us in the T-zone seeing as we have to seed cool season grasses at a time when it could either be 80 or 100 degrees, and more likely than not it's both.

The question I wonder is about is Phosphorous. I see that NC State recommends a 4-1-2 balance in the fall as late as November. I know it's a big No No for any P and K for notherners due to frozen ground and increase in snow molds. Since we don't have to worry about extended snow cover, are P and K big No No's for us as well?

In regards to N, I'm going to shoot for a give-n-take method. I want to take advantage of our extended season, but i don't want to push tender new growth when a big cold snap is coming. (a cold snap for me is lows in the teens, and maybe once every 2-3 years we will get single digits :lol: ) But If it's not going to get below freezing for a week or more (this is normal for me) then i might throw out .25#N / M. This will be my first year doing this on KBG so it's really a learning process for me as well.

 

[j4c11]

Keep in mind, that is soil temperature measured at 4", so the surface temp where the seed sits is going to be different and much closer to air temperature.

 

[social port]

I didn't even consider sunlight and surface temp vs soil temp. OK, so it sounds like there is nothing in the chart that would suggest a reason for changing the typical seeding/reseeding timeframe (late August-late September).

LawnNerd's strategy for fertilizing reminds me of a point made in a recent video by Pete from GCI Turf: Don't judge by a calendar. Instead, rely on weather forecasting.

I, too, would like to push the season as much as possible, especially since I am trying to correct P and K soil deficiencies. I don't want to fertilize in the spring, so small doses over the course of winter (unless the ground is frozen) is a really appealing idea.

 

[vnephologist]

I'm still pushing -0.5 lb N/M a week and ~0.33 oz/M PGR bi-weekly. The way I figure it, the more root growth I can promote without heat and humidity, the better. Regarding soil temps, I just finally had some poa germinate this past week. We're definitely on a different schedule down here.

 

[social port]

What is the 'M' abbreviation that you guys are using? I thought that the standard terms were per thousand square feet or per Acre
Also, vnephologist, where is your root growth coming from? Does the combination of nitrogen and PGR promote root growth?

 

[ken-n-nancy]

What is the 'M' abbreviation that you guys are using? I thought that the standard terms were per thousand square feet or per Acre.

The use of "M" for 1000sqft is traditional usage in the turf industry, particularly in the USA. Using "M" as an abbreviation for 1000 goes way back -- M is the Roman numeral for 1000.

An advantage of using "M" for agricultural usage is that it avoids confusion that can arise from using "k" for 1000 and having "K" be the chemical symbol for Potassium. There is no chemical element "M" so there is no confusion about whether "M" is referring to 1000 or a nutrient in the traditional agricultural community.

In other fields, such as finance, the use of "M" for 1000 has fallen out of favor, particularly with increased usage of the metric system. Instead in the field of finance, "k" is generally used for thousand ("k" is the standard metric system abbreviation for "kilo" = 1000) and "M" is generally used for million ("mega" = 1000000).

Personally, in my usage on this forum, I use "K" only for potassium and try to always use "ksqft" instead of just "k" if I'm talking about fertilizer application. For example, my most recent fertilizer application was of urea (46-0-0) at a rate of 1#product/ksqft, which was 0.46#N/ksqft. Back in August I made an application of sulfate of potash (SOP) at 2#product/ksqft, which was 1.0#K/ksqft. Traditional turf managers would have said those applications were at 0.46#N/M and 1.0#K/M.

Furthermore, I personally try to avoid the /M usage to avoid confusion between the traditional agricultural M=1000sqft and the newer metric usage of M=1000000.

For metric unit usage, capitalization conventions, etc., there's a helpful page with generally accepted conventions at the National Institute of Standards and Technology: Writing with Metric Units.

 

[vnephologist]

Also, vnephologist, where is your root growth coming from? Does the combination of nitrogen and PGR promote root growth?

Yes, the theory is that PGR limits top growth and pushes growth to the root zone.

 

[j4c11]

What is the 'M' abbreviation that you guys are using? I thought that the standard terms were per thousand square feet or per Acre.

The use of "M" for 1000sqft is traditional usage in the turf industry, particularly in the USA. Using "M" as an abbreviation for 1000 goes way back -- M is the Roman numeral for 1000.

How about square kilofeet :lol:
If anyone needs a good band name, feel free :lol:

 

[LawnNerd]

I'm still pushing -0.5 lb N/M a week and ~0.33 oz/M PGR bi-weekly. The way I figure it, the more root growth I can promote without heat and humidity, the better. Regarding soil temps, I just finally had some poa germinate this past week. We're definitely on a different schedule down here.

When will you stop N, or will you stop?

The NC A&T SU Research Farm weather station near me reported the following weather conditions in the past 12 month:

J4c11,

Can you post the link to that site? I'm wondering where they have their their station? Is it on their main campus, or off campus in a secondary site? I'm curious to check out the differences this year between Greensboro and Kernersville. It is definitely a little colder out here than in town. This morning is was 34 at my house, but 43 when i got into town.

 

[j4c11]

J4c11,

Can you post the link to that site? I'm wondering where they have their their station? Is it on their main campus, or off campus in a secondary site? I'm curious to check out the differences this year between Greensboro and Kernersville. It is definitely a little colder out here than in town. This morning is was 34 at my house, but 43 when i got into town.

Sure, I get weather info from CRONOS. The NCAT station is the nearest one to me.

https://climate.ncsu.edu/map/

 

[vnephologist]

I'm still pushing -0.5 lb N/M a week and ~0.33 oz/M PGR bi-weekly. The way I figure it, the more root growth I can promote without heat and humidity, the better. Regarding soil temps, I just finally had some poa germinate this past week. We're definitely on a different schedule down here.

When will you stop N, or will you stop?

I was thinking I'd let the weather and signs of growth/color help me determine when to stop. Always open to input from the fine folks here.

 

[social port]

What is the 'M' abbreviation that you guys are using? I thought that the standard terms were per thousand square feet or per Acre.

The use of "M" for 1000sqft is traditional usage in the turf industry, particularly in the USA. Using "M" as an abbreviation for 1000 goes way back -- M is the Roman numeral for 1000.

An advantage of using "M" for agricultural usage is that it avoids confusion that can arise from using "k" for 1000 and having "K" be the chemical symbol for Potassium. There is no chemical element "M" so there is no confusion about whether "M" is referring to 1000 or a nutrient in the traditional agricultural community.

In other fields, such as finance, the use of "M" for 1000 has fallen out of favor, particularly with increased usage of the metric system. Instead in the field of finance, "k" is generally used for thousand ("k" is the standard metric system abbreviation for "kilo" = 1000) and "M" is generally used for million ("mega" = 1000000).

Personally, in my usage on this forum, I use "K" only for potassium and try to always use "ksqft" instead of just "k" if I'm talking about fertilizer application. For example, my most recent fertilizer application was of urea (46-0-0) at a rate of 1#product/ksqft, which was 0.46#N/ksqft. Back in August I made an application of sulfate of potash (SOP) at 2#product/ksqft, which was 1.0#K/ksqft. Traditional turf managers would have said those applications were at 0.46#N/M and 1.0#K/M.

Furthermore, I personally try to avoid the /M usage to avoid confusion between the traditional agricultural M=1000sqft and the newer metric usage of M=1000000.

For metric unit usage, capitalization conventions, etc., there's a helpful page with generally accepted conventions at the National Institute of Standards and Technology: Writing with Metric Units.

Thanks for the information and all of the perspective that you provide here.
The only problem is, now I'm not sure which one I should use. :?

 

[social port]

I'm still pushing -0.5 lb N/M a week and ~0.33 oz/M PGR bi-weekly. The way I figure it, the more root growth I can promote without heat and humidity, the better. Regarding soil temps, I just finally had some poa germinate this past week. We're definitely on a different schedule down here.

If I am reading correctly, you are putting down close to two pounds of N per month. With the standard recommendation of 1 lb per month, why are you doubling the amount?

 

[vnephologist]

If I am reading correctly, you are putting down close to two pounds of N per month. With the standard recommendation of 1 lb per month, why are you doubling the amount?

Check out the "PS" at the bottom of g-man's original post... Fall Nitrogen Blitz. There are also some references to these amounts in other renovations here as well, I believe. I think the main downside is mowing frequency, but I've been able to cut at one week intervals with bi-weekly PGR apps. I should also note that the majority of my stand is in year two. Only a few spots that I leveled this Fall have a majority of new seedlings.

 

[social port]

If I am reading correctly, you are putting down close to two pounds of N per month. With the standard recommendation of 1 lb per month, why are you doubling the amount?

Check out the "PS" at the bottom of g-man's original post... Fall Nitrogen Blitz. There are also some references to these amounts in other renovations here as well, I believe. I think the main downside is mowing frequency, but I've been able to cut at one week intervals with bi-weekly PGR apps. I should also note that the majority of my stand is in year two. Only a few spots that I leveled this Fall have a majority of new seedlings.

Thanks. I remember reading that a while ago, but it wasn't in my recall.

 

[LawnNerd]

Vnephologist is "spoon feeding" the nitrogen. TTTF isn't as nitrogen hungry as KBG, so i can't say i would recommend spoon feeding TTTF. I'd stick to the 1#N / M (real quick, just use which abbrv. you prefer) for TTTF.

Question for the group, now that we are getting into cooler temps, do any of you switch to AS or AN?

 

[vnephologist]

Question for the group, now that we are getting into cooler temps, do any of you switch to AS or AN?

Oh good point! I might need to make the switch to AS this weekend. As osuturfman said "Urea requires an enzyme, known as urease, that's present in the soil to break it down into plant available forms of nitrogen. Urease is marginally effective at soil temperatures below 50 degrees F." ... "The bottom line is, use AS in the early spring and late fall and urea from late spring through early fall for best results." Also noting... "Higher carrier volumes when spraying ammonium sulfate (2.5+ gal/M) and irrigating within an hour of spraying the material."

[Edit to add soil temp chart]