# Starter Fertilizer When Overseeding



## cacuff (Apr 12, 2019)

Hi guys!

Been lurking for a while, but figured I'd finally post something since I have a question that doesn't seem to have been answered on the forum and maybe it'll help others that are planning their fall lawn renovation / overseeding.

Read the Cool Season Overseed Guide (https://thelawnforum.com/viewtopic.php?f=9&t=6250) and had a question about starter fertilizer.

I really like the idea of no nitrogen when putting the seed down, that way the new grass seed has a chance to grow a bit while the established grass is trying to figure itself out because it's been cut short. It was suggested to throw down about 1 lb/M of some 0-25-25 (giving 1/4 lb of each P and K). However, none of my local lawn and garden shops do custom blends of fertilizer, and I can't find anything in general without nitrogen in it.

I have come up with a few strategies:


Go with a 6-24-24 that my local home and garden store has. Putting down 1 lb / M would give 0.06 lb N, 0.24 lb of P and K. Would 0.06 lb / M - 0.24 lb / M of N really do anything at time of seeding to existing grass? This would give 0.24 lb /M - 1 lb / M of P and K each

Maybe put down 1 lb/M of each of a 0-0-60 and 0-44-0, giving 0.44 lb P and 0.6 lb K (something like this: https://tinyurl.com/y3dc8tow or this: https://tinyurl.com/y229pql4

Or put down something designed to promote blooming of flowers, a liquid 0-10-10: https://www.domyown.com/pennington-alaska-morbloom-01010-p-8721.html?sub_id=8722. Home Depot seems to carry it.

The math on the liquid option would look like this:
Product volume = 1 gallon
Product weight = 2.65 lb
Using analysis on bottle, 1 gallon of product contains 0.265 lb of P and K each.

Therefore, if I put out 1 gallon / M, then I'll be putting down 0.265 lb of P and K each.

Overall cost favors option 3, cost per lb of P and K favors option (and I'd have some left over for future overseedings or renovations).

Any thoughts? I think putting the post together helped me think it through and narrow down my options, but curious to know what you think.

Thanks guys!


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## saidtheblueknight (Jul 10, 2019)

You're overthinking it. Get some over the counter starter fert (I really like the Lesco version) and throw it down. No need for these custom blends from boutique stores.


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## Harts (May 14, 2018)

The other option is to skip NPK all together and just over seed. I've done this before with great success.


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## cacuff (Apr 12, 2019)

That's another thought I've toyed with, just skip the starter fertilizer, let the grass germinate and grow while the established turf figures itself out, then a few weeks in, hit it with a regular fertilizer. That'd cut down on costs for sure!


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## Khy (Jul 27, 2018)

1. The top growth is only part of why it's silly to throw down starter fert at the time of seeding. You also have to look at the half life of Nitrogen in the soil. If you're seeding say... KBG or TTTF, by the time the seed germinates, gets roots deep enough into the soil, all that nitrogen has already leached out of the soil due to watering. So even in the case of a renovation, putting down starter fert at seeding is pretty silly, most of that nitrogen is just getting washed away. So really, it's just a waste of money in general.

2. If you get a soil test and you're low on P or K those are different, they don't leach through the soil nearly as fast as N. In fact, a big issue many have is that P takes years to leach through soil. Where as nitrogen (depending on your soil type and amount of water) can take weeks. As for obtaining a no or low-N product that's still high in P and K that can be somewhat tricky. That said, the odds that you're low on both P and K probably aren't super high. And if that's the case you can usually find a 0-0-50 or something to that effect at a SiteOne or local garden center. Worst case, Amazon.

My personal preference is to throw out your N based fertilizer after the first mow. That should mean you have decent establishment at that point and are at less risk of harming the young seedlings with your fertilizer application (walking etc).


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## g-man (Jun 15, 2017)

^ +1 to what khy said


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## cacuff (Apr 12, 2019)

Yeah I'm leaning towards fertilizer at the first mow now that I think more about it. Thanks for the feedback!


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## ForsheeMS (May 21, 2018)

I agree with a few others. I would skip the fert altogether until the first cut and then drop some starter on it. Locally I purchase fertilizer at the local farm supply where the farmers buy their stuff. They have enough combos to satisfy most any needs and it's a lot cheaper than buying any of the fert blends from the box stores.

On the other hand, if your soil test indicates P & K are at optimal levels you really don't need to add any. (You did have a soil test done, right?) From there you could use an N only fert after the first cut.


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## cacuff (Apr 12, 2019)

I did do soil test! Just got the results yesterday!

P level was good, K was a little low, so some starter fertilizer wouldn't hurt.

Actually I'll probably pick up some 16-6-8 from Home Depot that I've had my eye on, that'd probably work too. It has sulfur in it, which will help with my pH of 7.8-8.0.


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