It sounds like it's pretty close, so personally? I'd say go for it.

Even if you get a little growth yet this season, it won't be much in temps below freezing during the day (even with re-warming your grass will be hesitant to grow much).

Timing on winterizer doesn't have to be perfect, just pretty good. And this sounds like it's pretty good at worst. :)

Nitrogen is not likely to be used by plants this late in the season.
It will be there in the Spring causing rapid top growth at the expense of root growth.
Up here in WI we are expecting the ground to freeze hard this coming week and those who put down fertilizers in the past 2 weeks have just wasted the amounts that will volatilize or erode away before the nutrients even gets into the soil.

Winterizer is applied when the grass is storing up carbs for the Winter/Spring growth. Lots of new research indicates that cools season grasses get no benefit from fertilizer applied as the soil temps drop.

>>Winterizer is applied when the grass is storing up carbs for the Winter/Spring growth. Lots of new research indicates that cools season grasses get no benefit from fertilizer applied as the soil temps drop.

Citation, please. Stuff changes, but I haven't seen this yet.

I found an interesting site from OSU that talks about fall and winter growth (maybe you've seen it). I don't think the article jives with what maplerbirch is saying. It does say, in a study on bentgrass, that no winter root growth was seen, but that is only part of the story.

http://turfdisease.osu.edu/turf-disease-updates/benefits-late-fall-fertilization

Notice that late Fall fertilization for N. Ohio is October up to December in S. Ohio, in the following quote from the aforementioned article:

"Turf fertilized in September and again during October, November, or December (northern, central and southern Ohio, respectively) is generally shown to possess better fall and winter color than a turf which was not fertilized at that time (1-4). In addition, signs of spring green-up have been shown to occur two to six weeks earlier if the turf has been fertilized during the previous fall. Most importantly, the enhanced rate of spring greening is realized without stimulating excessive shoot growth that accompanies the early spring nitrogen applications called for in most turf fertility programs. This can help homeowners and clients avoid the “spring mowing nightmares caused by very rapidly (easily resulting in the breaking of the 1/3 mowing rule)."

The geographic location for Chicago matches N. Ohio, while up here the grass fades by mid-Oct. and applications after that doesn't change anything.
This is a good article danielj_2009, I will continue reading. :)

>>It does say, in a study on bentgrass, that no winter root growth was seen

True. Northern grasses absolutely stop root growth at freezing (ground temperatures). Only very minor, insignificant root growth will occur at just over that.

Root growth maximizes at 50 to 65 for most northern species, and rapidly decreases below fifty.

However, our fall ferts are for root growth--winterization is for (indirect) synthesis into carbohydrates for winter storage, survival, and early greenup. As the article notes, that seems to work.

Skipping winterization in, say, Michigan wouldn't bother me too much if your goal is to avoid snow mold (which fertilization and greener winter grasses will encourage).

Unless one uses liquid fertilizer, one can expect a week or 2 delay in which the nutrients get into the soil as plant food.

The following paragraph of the article applies to Kentucky Blue Grass:

"Ohio State University research found that the spring color of late-season-fertilized turf remained quite good until late May or early June, when the effects of nitrogen applied the previous fall began to “wear off ”. A 0.75 to 1.0 lb. follow-up application of nitrogen is recommended at this time (late May-June) to maintain an acceptable level of turf quality throughout the summer period."

So from just the opening paragraphs of this article we discover that for Bluegrass lawns, we fertilize within a couple weeks of topgrowth ceasing and not again in the Spring until the color fades in May or June.

The remainder of the articles goes into the study of its growth cycles and analyzes the whys and wherefores of these conclusions. :)

>>Unless one uses liquid fertilizer, one can expect a week or 2 delay in which the nutrients get into the soil as plant food.

This isn't true--a water-soluble salt (AKA a synthetic fertilizer) applied just before a rain or final irrigation will go into the soil immediately.

Nitrogen forms flip, and only one is available to plants. But the flipping happens pretty quickly and pretty energetically even in cold weather.

Urea nitrogen applied late will take a few days to process, but the bacteria in the soil are still more than active enough to do that (and the enzyme is also excreted and freely available in all soils).

I've never applied a granular fertilizer that greened up the grass in less than a week, even with adequate rain, but I'll take your word for it that it becomes available in a matter of days.

Here we used to believe that fertilizer put down at Thanksgiving was a good rule of thumb. We would plan the holiday routine for fertilizing lawns, starting with Easter in the Spring.
I think the fertilizer salesmen set up that schedule.

Anyways we do not want to lose sight of what the article is teaching us so that we are not messing with the natural growth habits of the grass and wasting fertilizers.

>>I've never applied a granular fertilizer that greened up the grass in less than a week, even with adequate rain, but I'll take your word for it that it becomes available in a matter of days.

Danger, Will Robinson. That implies an imbalance in your soil in some nutrient and the plant is side-stepping a process and using an alternate route that's less efficient. This is one of the big tip-offs that you should have your soil tested.

Very low organic matter levels (which a good test like Logan or UMass will show) can also slow fertilizer response.

Optimally, synthetic fertilizers should produce visible green-up (if they're going to, mine don't as the grass can't get greener) in 48 hours after watering in.

>>Anyways we do not want to lose sight of what the article is teaching us so that we are not messing with the natural growth habits of the grass and wasting fertilizers.

Exactly. Winterization is one case where we do mess with it (to our and the grass' advantage).

Spring fertilization is unnecessary and, actually, harmful if done too early. Setting off massive growth in April merely taps the roots, reducing summer performance. But it does help the companies sell grass seed when your lawn thins out.

Fertilize no earlier than Memorial Day with synthetics. Organics, dealer's choice, but I still hold high nitrogen organics until May first, which will make them available to the lawn around May 21st and onward.

I never heard that when granular fertilizer does not cause the grass to green up within 48 hrs. of watering in it means there is an imbalance.
Is there a science that spells out the whys and wherefores of this notion?

It wasn't taught at the University and hasn't appeared in any horticulture papers that I've ever come across since.

Winterizer too late in the Fall only means early Spring application when the N becomes available as the grass begins to grow. That is a point of the article that commonly causes an upset in the fertilizing schedule.

Interesting conversation :)

"Winterizer too late in the Fall only means early Spring application when the N becomes available as the grass begins to grow. That is a point of the article that commonly causes an upset in the fertilizing schedule. "

Not exactly sure what you are getting at... do you mean that Winterizer on frozen ground(too late) results in it sitting there all winter until early spring when it can be used?

This would be true of organic fertilizers that won't wash/leach out of the yard. However regular urea will volitize into air and/or wash through and out of root zone with spring thaw and rains (before grass roots are actively feeding again).

Not the best for northern climates where extended freeze and heavy snow is common. Spring melts with frozen ground is very common...lots of run off.

Regarding the imbalance thing.... if you have missing nutrients, imbalance of nutrients, to high of some nutrients, poor PH, very high boron or aluminum amounts, etc. It makes for weak growing environment, no amount of nitrogen will fix that. Or at least the nitrogen will be under utilized.

This post was edited by BoatDrinksQ5 on Wed, Nov 12, 14 at 10:03

Applying a winterizer is universally supported by nearly all university turf programs. There have been a number of studies, with varying data measurements and differing theories, but all conclude that the end result is earlier green-up and greater root mass by the following Spring. The "why" may be open to debate, but the results are self evident.

>>I never heard that when granular fertilizer does not cause the grass to green up within 48 hrs. of watering in it means there is an imbalance.
Is there a science that spells out the whys and wherefores of this notion?

What BoatDrinks said. Glance at the nutrient availability curves; very low or very high pH will get in the way of availability and absorption.

As we already know from reading soil tests, low or high pH isn't a cause, it's a symptom. It arises from an imbalance in calcium, magnesium, and potassium levels (plus a few others, but those tend to be more minor in their influence).

Too little calcium? The plant can't develop structural material fast enough to keep up. Too little magnesium? It can't produce chlorophyll quickly. There are interactions going on with enzymes and proteins being produced, plus with absorption of every other ion.

It's not just pH. Low levels of boron, for example, give poor differentiation of meristem cells. Plus render photosynthesis far less efficient. And so on for every other element, even the most minor ones like copper and cobalt (cobalt is one of the few I don't adjust due to the toxicity of it).

>>Applying a winterizer is universally supported by nearly all university turf programs. There have been a number of studies, with varying data measurements and differing theories, but all conclude that the end result is earlier green-up and greater root mass by the following Spring. The "why" may be open to debate, but the results are self evident.

I tend to agree here; the research is firmly on the side of doing it (correctly, at the right time, using the right product in the right quantities).

Nitrogen at the soil surface at ground freeze is simply going to out-gas to the air and get lost. Or it runs off, erodes, or leaches. That's the wrong time.

Use of slow release in areas where the ground freezes does the same thing, just slowly. That's the wrong product.

Overuse of nitrogen will waste it as it leaches out past the roots (or burns the grass). Underuse is not enough to be effective. That's the wrong amount.

Use of 1 to 1.5 pounds of fast release nitrogen when topgrowth ceases but well before dormancy or ground freeze (with attention to the weather) visibly influences the lawn over the winter; I've seen it many times and research does prove that out.

Morph, you mention we'll before dormancy/freeze...

I see a lot of 'weekly urea app' discussion online - so moderate frequent apps while actively growing in the fall. (~.5lb-N/k)

That would lead me to believe that grass can at least to some extend utilize/store .5lbs of N easily in a week and be ready for more.

I know this utilization must slow when soil temperatures go from 60° to 50 to 40....

If that same .5lb-N/k is applied late fall, does that week turn into 8-10days? Or no change ?

If so (to some extent) - when dropping a full pound of N for winterizing on somewhat hungry grass(haven't fertilized in say a 4-6wks).... is that nitrogen mostly absorbed in a week? Two weeks?

Just curious since this year gotta a little crazy here in MN... went from fairly cold and low growth to just downright freezing and a foot of snow. Probably only got 6days of soil temps at or above 35°F from the time it got watered in.

>>>Use of 1 to 1.5 pounds of fast release nitrogen when topgrowth ceases but well before dormancy or ground freeze (with attention to the weather) visibly influences the lawn over the winter.

Visibly---I'll second that. You may not be able to see increased root mass, but I've visibly noticed a healthier, thicker lawn every season after I started winterizing my BG 5 years ago. Less disease (none in fact- ymmv), much less weed infestation, better drought resistance, and just dang-better general appearance.

>>>I see a lot of 'weekly urea app' discussion online - so moderate frequent apps while actively growing in the fall. (~.5lb-N/k)

A MGP and spoon feeding question. That'll take morph a few pages, Lol.

haha - yeah....

mainly wondering about temperature relationship and how that then applies to winterizing and possible under-utilization /leaching.

last two years i push for later application (growth stop) but then I always end up fearing it was too late... oh well.

Need to frequent This forum more to feel better about 'forgiving if a little early' side of the fence. lol

>>A MGP and spoon feeding question. That'll take morph a few pages, Lol.

Given my verbosity, yes. :-)

Technically? If you feed organically, you are always spoon feeding. Organic breakdown is slow, depends on the soil bacteria and fungi, and feeds the lawn indirectly and in smaller amounts...but all the time. Nitrogen tests, compared to a synthetic lawn in exactly the same circumstances, will show much lower nitrogen spikes on the organic lawn, but a much more extended release period.

That soybean meal I dropped on October first is still out there, feeding away. For that reason, when I publish my yearly numbers, people often ask me why I go so low on the winterizer nitrogen. It's because I've already got a boost from the organics (particularly this year where fall lasts two days--I really cut back the winterizer).

>>Morph, you mention we'll before dormancy/freeze...
I see a lot of 'weekly urea app' discussion online - so moderate frequent apps while actively growing in the fall. (~.5lb-N/k)
>>That would lead me to believe that grass can at least to some extend utilize/store .5lbs of N easily in a week and be ready for more.

It can, although I would find 0.5 pounds of N per week a bit excessive in most cases. Potential losses to the air and to leaching are simply too high, and I don't see the need to poison my water table with nitrates.

Spoon feeding requires a great deal of attention to the weather.

I'd also only recommend it on younger grasses to get them to mature faster, or damaged grasses you're trying to get to repair their area. I have one tiny area--maybe ten square feet--I've fed synthetically through September and October to get it to repair heat damage.

>>I know this utilization must slow when soil temperatures go from 60° to 50 to 40....

You'd be surprised. Between sixty and fifty, top growth slows. Root growth, on the other hand, accelerates. And there's nothing special about root mass, it's made of the same stuff the top growth is, just in slightly different percentages and with far more lignin to hold it together.

Fifty to forty, root growth starts to slow, but it's still pretty good in the upper forties and still going at 40.

Still, as we fall through the forties, requirements go down. More of that nitrogen is indirectly being processed into carbs.

Fall under forty and root growth really slows, stopping just above freezing or so. Requirements at this point are minimal, a single winterization and off you go.

>>If that same .5lb-N/k is applied late fall, does that week turn into 8-10days? Or no change ?

I'd extend times as soil temperatures at four inches fall under fifty, but I'd only be winging it as I'd be using the SCAN site close to me, which tends to read cold compared to my soil.

Off the cuff, without sitting down and doing all the math, I'd say 10 days at 50. Stop below that and wait for winterization--the grass is moving into its fall lull period.

>>If so (to some extent) - when dropping a full pound of N for winterizing on somewhat hungry grass(haven't fertilized in say a 4-6wks).... is that nitrogen mostly absorbed in a week? Two weeks?

Days, but there are considerations. Soils that lack organic matter (and therefore also lack a good population of bacteria and fungi) give the roots only one good chance to grab the nitrogen before it washes past and gets lost (a perfect rainfall for your soil type will optimize that tendency).

Soils with high OM and high bacterial/fungal populations tend to grab the nitrogen, and they're better at it than roots are. The roots still get a good bit, but much of the resource is bound to the organics, or locked in bacteria or fungi.

Over time, your grass releases carbohydrates to the soil, and the bacteria and fungi respond by sending nitrogen back to the plant (it's a handy symbiosis for all the species). Bacteria also die due to bacteriophages (usually viruses, but some insects and worms like heavy bacterial mats for dinner as well). The remaining bacteria get a second shot at the nitrogen, as does the grass.

So while the simple answer is "days," a healthy soil can extend the actual answer to "weeks, months, years."

Still, the main burst is when it gets watered in. That's why most fertilizers state on the bag, "Greens in 72 hours." Because they do.

Root storage of nitrogen is very poor, but they're happy to send it along and use it to grow leaf area, create chlorophyll, and so on to transform it into carbohydrates as the greener, larger leaves absorb sunlight.

That effect usually lasts about six weeks with good rainfall.

Which is another point. There's an effect we call "boomerang" where you feed the lawn synthetically, it greens, and two weeks later it looks lousy again. That's usually caused by the above-noted lack of organic matter and healthy soil populations of bacteria and fungi; that symbiosis is weak.

That quick shot of nitrogen gets absorbed, used, used up, and you're back where you started (or worse as synthetics also burn off organic matter). There's no remaining trade going on with the micros because the micros can't set up a nice marketplace.

The solution there is to increase organic matter, feed organically, and wait for the system to restore itself.

Spoon feeding can be used as a way around that tendency, but it does the soil no good and you're stuck spoon feeding for the rest of time. Amounts used to combat the boomerang effect can be much smaller, on order of 0.25 pounds of N per thousand per week.

Sorry, I forgot the link. Choose the SCAN site closest to you.

Greencast also has a map: http://www.greencastonline.com/tools/SoilTempMaps.aspx

I don't find Greencast to be terribly accurate (and it's not as in-depth as the SCAN information) but if you don't have a local SCAN site, this is far better than nothing.

Here is a link that might be useful: SCAN Site Map

Well anyways I think the "Summary" of the article is worth noting for the Chicago question:
"Late-season fertilization lengthens the fall/winter green period and enhances the rate of spring green-up without stimulating excessive shoot growth, thus allowing the turf plant to maintain higher levels of carbohydrates than when spring/summer fertilization is used. This provides both aesthetic and physiological benefits to the plant and customer/client. Nitrogen applied during early spring increases shoot growth rates and decreases the levels of available carbohydrates in the plant, resulting in depressed root growth rates. Late-season nitrogen applications have no similar negative effects on root growth and, in fact, increase root growth during mid winter to early spring. Better carbohydrate storage and root growth ultimately result in a more stress tolerant turfgrass plant during stress periods. No winter damage or snow mold injury occurred as a result of late-season nitrogen applications in OSU research."

We should remember that this article is talking about cool season grasses in the Midwest and that the fall application time would occur when soil temps range from 40 - 65 degrees.
I wonder what the soil temperature is in Chicago, now?

While Greencast reports Chicago's soil temperature between 30 and 35, I find that unlikely (or they're measuring the surface soil temperature, not the root zone at 2 to 4 inches). Greencast has my soil temp at 40, while the SCAN site puts it at almost fifty--and my closest SCAN site is further west and at much higher altitude.

Platteville, WI is the closest SCAN site to Chicago, further inland, further north, and further up by a good clip (as well as not bordering a massive Great Lake). Soil temperatures are 35 to 37 in the 2 to 4 inch range even there.

Edit To Add: Forgot the upshot. Now, a week after the OP posted, it's getting more marginal than it was, but it would still be just barely OK to winterize. If Platteville is 35 to 37, the Chicagoland area will be 40 or slightly above.

This post was edited by morpheuspa on Thu, Nov 13, 14 at 13:32

Maybe a dumb question, buy why can't you just shove a lab thermometer down into the soil and read the temperature?

>>Maybe a dumb question, buy why can't you just shove a lab thermometer down into the soil and read the temperature?

NOT dumb. You could, if you're sure that no heat is being transmitted down the tube. My compost thermometer (24" stem) would work, but I'd have to watch that the stem is insulated if air temperatures really differ from soil temperatures.

You want to put that last app of fertilizer down when it is around 40deg....not up at 65...

At 65 grass is still in full growth mode... grass shoot growth still is active and prime until around 60deg soil temp. Where as at 40 top growth/shoot growth ceases.
http://postimg.org/image/ody59io4f/

You want to put the Winterizer down for carb/energy storage ...not spuring green grass growth.

When you are done mowing for the year (growth stoppped pretty much) then you are ready. Usually lots of freezing temperatures.... snow soon...(or flurrries already)

>>>You want to put the Winterizer down for carb/energy storage ...not spuring green grass growth.

Spring grass GROWTH or do you mean early Spring green-up?

I mean late fall growth spurt

the storing of nutrients in the fall will result in healthy green grass in the spring. :)

Grass slows down blade growth in the fall as light levels and soil temepratures drop, mowing intervals go from 4-6days...to 8 days.... to 10days..... to get the same .5" cut off.

IF however when it starts to slow significantly and soil temperatures are in the 50-60°range... and you hit it with a .5-1lb of fast acting Nitrogen, top growth will flush and get growing again. not good for grass or snowmold etc.

This post was edited by BoatDrinksQ5 on Fri, Nov 14, 14 at 10:48

It does require some attention to the weather, and some attention to soil temperature.

Although fifty yesterday, today's soil temperatures are topping out in the low to mid forties. My winterizer got watered in last night in a mixed rain/sleet/snow event.

The window of good soil temperatures looks like it'll last about three days.

It is a bit of a crap-shoot and may be more dependent on the skill of one's green thumb. I think we all agree that once soil temperature reaches 33 F. or below, winterization fertilizer is done. Applying it before the turf has significantly slowed or stopped top-growth and you may experience flush and possible snow mold issues. As "dormancy" (specifically for this purpose: decline of top-growth) appears to be dependent not just on temperature, but also day length, the window for winterizing can get squeezed or expanded from year to year by the whim of Mother Nature as it has this year. Regardless, due to the benefits to be derived, Although soil temps are rapidly falling below 40F here, I'll still be applying urea and grabbing what benefits occur during those times that soil temperature remain or rise >32F and before the nitrogen dissipates.

This post was edited by yardtractor1 on Fri, Nov 14, 14 at 12:50

Yep, sometimes you just roll the dice. I just rolled them.

Given the weather projections, the worst I'm going to end up with is about average results. Even if it gets warm again, it won't slip out of the average range at this point.

Doing this too close to soil freeze means the results are far below average (to downright wasteful). Too early and it doesn't winterize, it's just a late feeding.

>> morph: NOT dumb. You could, if you're sure that no heat is being transmitted down the tube. My compost thermometer (24" stem) would work, but I'd have to watch that the stem is insulated if air temperatures really differ from soil temperatures.

With a real glass lab thermometer I don't think this is too much of an issue. It seems to me it would be ideal to have a metal rod the same diameter as the thermometer (glass). Pull the rod out, slide the thermo in and pack down the soil a little around the stem. I think the temp reading would stabilize in just a few minutes. Since the mercury that matters is 4" down, I don't see a problem with false readings in just a few minutes time. If you leave it in there overnight with freezing temps, then maybe you've got an issue. Or, get a 4" long thermometer!! Never seen a compost thermometer though.

The concern for cool season grasses using N to start growing leaves again as a result of the late Fall application was addressed here:

"For the late-season concept to work successfully, it is essential that the turf be green when the late (October / November/December)) nitrogen application is made. In central Ohio, this means that 0.75 to 1.0 lb of quickly available nitrogen (such as urea, urea/PCSCU, urea/IBDU or highly-active MU, etc.) should be applied during September. This will ensure that the grass will remain green late into the fall when the actual late-season application will be made. It is also important, however, that excessive shoot growth not be encouraged by over-application of nitrogen during September. The production of lush, succulent growth then may decrease cold tolerance and increase the incidence of the snow mold diseases during the winter and following spring. For the same reasons, the(late-season)October/November/December) application should be delayed if extended periods of unusually warm weather (average daily temperatures greater than 55-60 F degrees) are being experienced, or are forecast. In Ohio, the general timing recommendation is late October, November and late November/December in northern, central and southern Ohio, respectively."

So it is important that the September application doesn't spark lush growth but gets the growth to be normal and green. If the grass is growing normally the Fall nitrogen should not have a huge effect on top growth as long as the temps remain cool.
Coordinating the 2 applications seems to be a critical step, rather than just 1 app in the late Fall.

That's usually contained in our lull season recommendations (don't feed much in October in my area, in other words). On the up side, barring a very warm and wet fall, it's much harder to spark excessive growth in fall than in spring, when the grass wants to grow as excessively as possible.

That having been said, I break that rule. Every single year. Except I feed organically so the system moderates itself very nicely.

"Fall" applications are around August 1, September 1, and October 1. Since the decay cycle trickles nitrogen, I get a modest response starting in late August, peaking in mid to late September, and gliding down as temperatures cool through October. At no point is the nitrogen level excessive, nor does grass growth ever rise to insane levels.

The rules are a little different when feeding organically since it's strongly dependent on soil temperatures, moisture levels, and bacterial action.

That is the excellence of organic fertilizers, morpheupsa.

Perpetually feeding the soil as fertility rather than an instant fix, rises and falls with the same microbial activity as the grass itself.
The grass has food coming available when it wants it, in its natural growth habit, rather than being artificially stimulated from a rush of water soluble N.

Exactly. Except, of course, that once a year when I winterize.

The lawn currently has around 0.9 pounds of nitrogen flowing in, all synthetic, all a rush, and all artificial.

Of course, it's currently 41 out there and that's our high. Tonight's low will be in the twenties. There's no growth flush that can happen.

Although the color sure is turning greener between the winterizer getting washed in and the iron I sprayed.