# Fall fertilizer after over seeding



## jeffman2 (Apr 8, 2019)

I live in Massachusetts and have a cool season grass of tttf and kbg. I did my overseed two weeks ago and sprayed tenacity at seed down. I will be reapplying tenacity at four weeks and every month from there on until frost. 
After seed germination I applied a 10-20-10 starter fert. I am thinking of applying a second dose of starter fert in 2-3 weeks but am also wondering if I should do some small doses of urea every few weeks. 
Any tips on this?


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## Harts (May 14, 2018)

I would just do one more app of tenacity. Depending on the rate you use, there is a max limit. A late season app also won't do anything that will help come spring time. In my opinion, more than one more app would be a waste.

For fert, I would just do weekly or bi weekly apps of urea. 1/4lb N (weekly) or 1/2lb N (bi weekly). Quick release nitrogen is best used this late in the season.


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## jeffman2 (Apr 8, 2019)

Thank you for the tips! Would you suggest one more app of starter fert and then the urea?


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## Lawn Noob (Jul 26, 2020)

Tagging this thread. It is relevant to me too.


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## ken-n-nancy (Jul 25, 2017)

jeffman2 said:


> Would you suggest one more app of starter fert and then the urea?


Have you done a soil test to see if you need phosphorus?

Do you still have some starter fertilizer left over from your prior application?


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## jeffman2 (Apr 8, 2019)

I did a soil test a year ago and phos was a bit low but not drastically low. No I don't have any starter fert left. I am trying to decide if I should do a second bag of starter fert or start spoon feeding urea.


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## Harts (May 14, 2018)

I wouldn't buy any if you don't have it. Just use the Urea. You likely only have a few weeks left to apply N anyway.


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## corneliani (Apr 2, 2019)

If that starter fert is a quick release nitrogen then you may have one more application left. The chances are that there's some % of SRN in that mix though which means it'll release over 4 weeks, +/-. If the add'l P is something beneficial for your soil and you prefer the slower release of a granular application then by all means do it. Just keep an eye on the forecast. If the weather turns on you then your applied N is lost, hence the benefit of an urea or AMS product at that point in time.


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## jeffman2 (Apr 8, 2019)

I looked at my soil test from a year ago and my P came out "very low" at 1.5 with an optimum range of 4-14. My K was also "low" at 63 with an optimum range of 100-160. 
So I am thinking I can do two things:
1) apply another bag of starter fert 18-24-6 48lb bag in 2 weeks. 
2) Then I can EITHER apply .25lb N via urea 48-0-0 every week starting in October, likely only 3 apps OR I can wait until end of Oct or early November and apply a winter fertilizer like Jonathan Green Winter Survival 10-0-20 45 lb bag. 
Any thoughts?


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## ken-n-nancy (Jul 25, 2017)

Harts said:


> I wouldn't buy any if you don't have it. Just use the Urea. You likely only have a few weeks left to apply N anyway.





jeffman2 said:


> I looked at my soil test from a year ago and my P came out "very low" at 1.5 with an optimum range of 4-14. My K was also "low" at 63 with an optimum range of 100-160.
> So I am thinking I can do two things:
> 1) apply another bag of starter fert 18-24-6 48lb bag in 2 weeks.
> 2) Then I can EITHER apply .25lb N via urea 48-0-0 every week starting in October, likely only 3 apps OR I can wait until end of Oct or early November and apply a winter fertilizer like Jonathan Green Winter Survival 10-0-20 45 lb bag.
> Any thoughts?


Harts is absolutely right that the most important nutrient your new grass needs is nitrogen.

Given that you've now added the information that you tested low on phosphorus last year, I'd highly recommend applying another dose of starter fertilizer (something with significant amounts of both nitrogen and phosphorus) when you are next due for fertilizer, which sounds like it is in a couple weeks. Something like the 18-24-6 you mentioned, or Scotts Starter 24-25-4, where most of the N is quick-release.

If it were me, I'd make that first application of the starter fertilizer at a rate of about 0.5#N and 0.5#P per ksqft, and then continue making weekly applications at the 0.25#N/ksqft (and 0.25#P/ksqft) rate until about the 3rd week of October for metro Boston. (I'm just 50 miles away.)

I'd recommend staying away from late fall fertilizers with significant potassium, due to increased risk of snow mold, for places that have a significant risk of 40+ days of continuous snow cover during the winter. Depending upon specifically where you are in metro Boston, that may be more or less likely.


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## Harts (May 14, 2018)

I would also add that N apps in late October or early November won't likely be beneficial to your lawn. I'm going to assume (and maybe I'm wrong) that in early November you won't have much, if any top growth. Maybe you can get one app down, but that will likely be all.

And I would avoid the potassium as Ken N Nancy mentioned if you have extended snow cover.


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## jeffman2 (Apr 8, 2019)

Thank you everyone for the great suggestions! This truly is a great board!


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