# Advice on low dose liquid N spoon feeding of seedling grass during Fall slowdown?



## Green (Dec 24, 2017)

I overseeded late, and then got washout and had to do it over again, so the grass is very young right now. It's in that early-growth phase that is extremely slow, and hopefully will be ready to cut in about a week.

Due to cooler temps and both real and average first frost in a day or two, I strongly feel it's too late to push growth with the comparatively high doses (even spoon feeding) from granular fertilizers. This being to avoid increased Winter damage or snow mold.

I'm open to using low dose liquid apps, however, to get a bit of N, P, K into the new grass starting as soon as it's ready to mow.

First, anyone feel this is appropriate to do? Second, I was thinking of doing 0.05 lb/M for each app every week. Does this sound ok? Or use even less?

I typically do the final mow in early December. So, how many weeks could I get away with applying the liquid fertilizer? Could I go right until the end? I will be dropping a half dose final winterizing app of 0.5 lb N/M at the very end of the season as well.

I know it's a lot of questions, but some of you are pretty experienced with liquid apps, so I wanted to post this a good week ahead of time in order to get the best advice. My current experience level with liquid fertilizing is not zero, but I am new to it. I have done it a bit this Spring on grass planted the previous Fall (at up to 0.2 lb N/M) but that's it.


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## Suburban Jungle Life (Mar 1, 2018)

I wouldn't worry too much about first frost. Sure, that is an indicator that the grass will be slowing down soon. The grass will keep growing with soil temps into the 40's. I find that the mid to low 40's is where it seems to stall. Check greencast. What are you current / average daily soil temps?


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## Green (Dec 24, 2017)

@Suburban Jungle Life, I am inland, in Zone 6B. There's a huge difference in temps here versus the coastal part of the state which is 7A. I don't believe in putting down granular synthetic fertilizer past the end of this week or so, partly for reasons mentioned above, and partly due to reduced uptake. I feel new grass is especially finicky. So, I see the liquid route as the best option.

0.05 lb may seem small, but liquid is supposed to have better uptake. I'm not sure about in cool weather. If I did it every week for 4 weeks, it would add up to almost a full granular spoon feeding app, but probably with much better uptake efficiency (?).

I have not checked soil temps in a few weeks. I will today. I don't find Greencast accurate for my area.


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## g-man (Jun 15, 2017)

Green, Im not sure of this approach. Liquid nitrogen is absorbed via the leaves thru ET too. There has to be movement of moisture from the leaves to the roots/crown area to be able to take the nitrogen there. ET drops with lack of sun (duration and intensity) and lower soil temps. Granular or liquid should all be the same.

If you want to trick mother nature, then heat lamps and grow lights.


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## Suburban Jungle Life (Mar 1, 2018)

Maybe adding an organosilicone to the foliar N will help with stomatal flooding. I think that would force N into the leaf but I'm not sure whether that would be a good thing or not...


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## Green (Dec 24, 2017)

I think I'm just going to go for it as stated...unless someone really knowledgeable comes in with better rates to use. I picked 0.05 because it's half of 0.1, which is a pretty standard liquid rate. And also because it's the amount that FAS uses at the 4oz rate, and FAS is fairly effective in cold weather into the upper 30s.

I believe I remember osuturfman saying recently that spoon feeding very low rates during the slowdown is perfectly ok.

What I don't want to do is put 0.25 lb of granular outside, and have it mostly just leached...that's misuse.


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## Turfguy93 (Aug 30, 2017)

@Green try doing .10 lbs N per 1000 weekly from ammonium sulfate until growth stops and put in a little bit of chelated iron, manganese, sulfur product every other week. I think you'll be happy with the results


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## drenglish (Jun 22, 2018)

Im spraying 0.25lb N/M each week from Urea and about to switch to AS....but this is during active growth and good weather. On a new reno of TTTF/KBG. @Green you're considering the lower rates mainly because of slow growth and cold weather?

Anyone else spraying 0.25 lb N/M or higher? I like the accuracy of the sprayer over my Wizzer or small push spreader.


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## Green (Dec 24, 2017)

@Turfguy93, haven't seen you lately here but was secretly hoping you'd reply. Thanks for the advice. I have a product containing ammonium phosphate...what do you think of that for this use?

I also have a very small amount of ammonium sulfate, as well as Ferrous sulfate...and another product with ammonium sulfate and some micros. This one also has potassium and phosphorus. Does the snow mold thing still apply when spoonfeeding in the Fall with low doses of potassium via foliar spray?

Also...no surfactant, right? I do have NIS if needed, though.


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## Green (Dec 24, 2017)

@drenglish, yeah, and burn potential on new grass. Plus, the colder it is, the less is utilized, so more is just a waste.

And yeah, that's another motivation for spraying. Much easier to get small amounts down. Granular it's hard to go under 0.25 unless you have a really low analysis fertilizer.


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## Green (Dec 24, 2017)

g-man said:


> Green, Im not sure of this approach. Liquid nitrogen is absorbed via the leaves thru ET too. There has to be movement of moisture from the leaves to the roots/crown area to be able to take the nitrogen there. ET drops with lack of sun (duration and intensity) and lower soil temps. Granular or liquid should all be the same.
> 
> If you want to trick mother nature, then heat lamps and grow lights.


Not so much tricking anything...but being able to measure the low amounts is easier with liquid solutions regardless of whether it absorbs more efficiently or not (which maybe @Turfguy93 can chime in on).


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## Turfguy93 (Aug 30, 2017)

Green said:


> g-man said:
> 
> 
> > Green, Im not sure of this approach. Liquid nitrogen is absorbed via the leaves thru ET too. There has to be movement of moisture from the leaves to the roots/crown area to be able to take the nitrogen there. ET drops with lack of sun (duration and intensity) and lower soil temps. Granular or liquid should all be the same.
> ...


With ammonium sulfate you should still get uptake foliarly. Uptake of nitrogen slows down in the fall when et drops because nitrogen in the soil is taken up mostly by mass flow. So less water taken up less nitrogen taken up. The low dose spoon feeding along with nitrogen and iron should help the grass mature and produce more sugars with more the extra chlorophyll it has which then can be transported to the roots and crown. I'd just go straight ammonium sulfate and ferrous sulfate if you have it. Maybe throw in the micros every third app. If your soil test showed decent levels of phosphorus and potassium I wouldn't worry about spoon feeding them this late


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## Green (Dec 24, 2017)

@Turfguy93, thanks. Any opinion based on experience or studies you've seen on the ammonium phosphate mixed with ferrous sulfate uptake in cool weather? Because I have a little of everything, but not enough of any one nutrient for weekly apps at 0.1 lb/M with the same thing. I was thinking of mixing them to get the right amount of N in the solution. I have some ammonium phosphate fertilizer and some ammonium sulfate fertilizer. Does ammonium phosphate work as well in cool weather?


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## Turfguy93 (Aug 30, 2017)

@Green if that's what you have use it, shouldn't harm anything. Phosphate isn't taken up well foliarly though so I would water it in the next morning


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## g-man (Jun 15, 2017)

@Turfguy93 when do you stop the liquid application on a Reno area?


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## Green (Dec 24, 2017)

Excellent question @g-man


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## Turfguy93 (Aug 30, 2017)

g-man said:


> @Turfguy93 when do you stop the liquid application on a Reno area?


You can keep spoon feeding until growth stops. If it's real cold and growth is slow you can go to biweekly instead of weekly


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## Green (Dec 24, 2017)

@Turfguy93, the soluble fertilizer I have that has the ammonium phosphate also has potassium nitrate. I couldn't find much about whether that works well for foliar uptake or not. If not, I'll buy some more ammonium sulfate.


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## Turfguy93 (Aug 30, 2017)

Ammonium based fertilizers are taken up better foliarly than nitrate nitrogen


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## Green (Dec 24, 2017)

Turfguy93 said:


> Ammonium based fertilizers are taken up better foliarly than nitrate nitrogen


Good to know. I'll buy more ammonium sulfate. Thanks.

Now, as far as the iron, as mentioned I have Ferrous sulfate. I'm not sure if I want to use that, because it will stain the sprayer. I'm leaning away from it. But just for curiosity (or if I use my handheld sprayer and decide to do it)...I'm guessing the amount used in the mix would be very low...less than used for FAS. How many grams per thousand square feet are we talking? Grass is Northern mix, but I'd say the bulk of the overseed was with TTTF. There is also a lot fine fescue involved (mostly existing, but also some from seed).

Also, does chelated iron stain too?


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## Green (Dec 24, 2017)

Also, I'm assuming Iron EDTA is a chelated iron.


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## Turfguy93 (Aug 30, 2017)

I've never had a problem with chelated iron staining and Im just careful around concrete. Ferrous sulfate would be 1 oz/M every 2 weeks I believe but I would go the chelated route at 2 ounces/M every 2 weeks. And yes edta is chelated


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