[bassadict69]

I have about 25-30 lbs of 33-0-0 and a 40 lb bag of 13-13-13...

I would like to mix the two so I can broadcast once...is there a formula or way to figure out how much of the mixed fertilizer to use over my 12k backyard? or will it simply take all of it?

 

[kur1j]

@bassadict69

You have (.33 * 30lbs ) + (.13+ 40lbs) = 15.1lbs of Nitrogen combined in both bags. If you spread that over 57k sqft you would apply .26lbs of N over your grass, so yeah you would be fine (if you are throwing it out over what's in your profile). You would be throwing out significantly less P and K (use same method to find out how much).

 

[bassadict69]

This will be spread over my 12K sq ft back yard only... so if I am figuring correctly, that would be just over 1.25 lb per k.

 

[Spammage]

This will be spread over my 12K sq ft back yard only... so if I am figuring correctly, that would be just over 1.25 lb per k.

About 1/2 that should be sufficient for St Augustine. I would mix the products together, weigh out half and apply. Store the remaining product for a month+ and then apply it.

 

[bassadict69]

Thanks guys!

 

[Movingshrub]

This will be spread over my 12K sq ft back yard only... so if I am figuring correctly, that would be just over 1.25 lb per k.

Do you have a particular amount of nitrogen you're seeking to put down per 1k? Otherwise, I'm going to assume you're wanting 1lb of N per 1k sqft of lawn. With that being said, 1lb of N a month is normal for Bermuda but sounds heavy handed for St Aug so you probably want to put down less. Without further ado, onto the math.

If you're wanting to put down 1lb of N per 1k sqft, you can spread that entire bag of 33-0-0 (assuming 25lb) and that would get you 0.63lb of N per 1k sqft. If it's 30lb of 33-0-0, that gets you to 0.76lb of N per 1k sqft.

So, use the entire bag of 33-0-0, and depend on how much of that you have you are going to use the all purpose fertilizer to make up the difference in nitrogen.
If you have 25lb of 33-0-0, use 37lbs of the 13-13-13
If you have 30lb of 33-0-0, use 24lbs of the 13-13-13

37lb * .13 = 4.81lb of N total/ 13 ksqft=0.37lb of N per 1k from all purpose
24lb * .13 = 3.12lb of N total/ 13 ksqft=0.24lb of N per 1k from all purpose

 

[bassadict69]

I was kind of thinking 1lb per K based off what I read on this site. The yard is a major work in progress with part of it being some nice thick SA, and others being thin, weeds, etc. I have some great runners all over and things are really beginning to thicken and spread which is my goal.

 

[kur1j]

@bassadict69 Most people you see on the warmsection have bermuda which is hungry for N. I don't have any experience with SA but from my understanding it doesn't require near the same amount of N. I would probably do what spammage said and back it down and use the rest later.

 

[Movingshrub]

https://www.uaex.edu/publications/pdf/FSA-6119.pdf