You're spot on. It depends on how much slow-release nitrogen is in that 29% number. Ideally you go with Ammonium Sulfate or straight Urea. Lowes sells a 20.5-0-0 AMS that should work well for this.

 

For what is worth I did my first feeding a bit early used Lesco 30-0-10 2% Iron .90lbs/1000
It was on clearance at Lowes $57/50 hard to say no
Per label it appears to be 12% Slow Release
The rest of the season will be with the
20-0-0 Sta-Green product from lowes $25/40lbs

 

Two years ago, I used a bag that had a mix of slow and fast release N. I think it's fine to do for your first couple of apps. Most of that slow should get used up before end of growing season. Once you start to get to the latter part of Sept, I'd switch to something more quick release.

 

I was at my local lows picking up some fert and stumbled upon sta green 22 0 0 on clearance for 4.75 per bag. 7% of the 22 is slow release.

 

Nice , not much of anything on clearance locally . A few damages bags where 50% off. Its been tough on the clearance deals
Last good deal was homedepot clearance on Lesco Stonewall $15/bag I bought the 4 that where lest. That was 2021

 

So the 29-0-3 has 11.6% slow release (polymer coated urea). So 17.4 is fast release Urea. .5/.174 = 2.87lbs per 1k sq ft. I have a 50lb whole bag of this stuff that i bought at some point. I have about 10k sq ft. So im gonna need more than just this bag. Im thinking it should be ok to use the first two apps. I need 28 lbs for my whole property. Should i apply once a week or once evry 2 weeks?

 

I would split that bag in half do one application now and another two weeks later it's like a spoon feeding with a splash of slow release to carry over

 

Where are you located at plays into this. If I missed it, my apologies. If you are further south closer to the transition zone your grass might be still slowly growing into November. In MO last year my last cut was the first week of November. Even if the grass isn’t growing vertically it is still taking in some N into the roots. IIRC, it is this N that helps with the spring growth. I have found what is cheapest and go with that. Damaged bags are great but like others have found it hard to come by this year. Urea has been the cheapest so far and I am doing about .5# every two weeks through October. I am still spraying a little N and Fe for the the month of September.

 

Im in Northern Delaware