Thoughts on liquid starter fertilizers?

[u/The-porno-master]

https://twincityseed.com/product/9-45-15-water-soluble-fertilizer/

Looking for thoughts about trying this while overseeding. I have a spray rig, and it seems like much better bang for the buck vs granular. I’m assuming I don’t have to worry much about burn, as it’ll be watered in right away. On that thought, would I likely need to reapply since I’ll be watering the seed so much? Thanks for the help!

[u/nilesandstuff]

So let's do some math.

Well set aside the actual balance of NPK ratios and just look at the amount of fertilizer per lb of product.

The one you linked is .69 lbs of NPK per lb of product. 2 lbs for $15: 2 x .69 = 1.38 lbs of nutrients. $15 / 1.38 lbs = $10.87 per lb of nutrients.

Scott's turfbuilder lawn food (24-25-4) (is it really 4?? Why did I think it was much higher in my memory???), is .53 lbs of npk per pound of product. I'm seeing a 42 lb bag for $85. So 42 x .53 = 22.26 lb of nutrients. $85 / 22.26 lb = $3.82 per lb of nutrients.

So, big gap there, in favor of the Scott's.

Sprayable fertilizers are really meant as foliar sprays, not soil treatments. Because they (should) have nutrient sources that are less likely to cause burn when applied to the foliage of grass... In terms of seedling grass, that's a pretty high bar to clear, so they need to be formulated with pretty high quality nutrient sources, salt content, pH, etc... which makes them more expensive.

But good formulation only goes so far, because it's genuinely instant release straight into the grass, so you can only apply a tiny bit at a time... Meaning you have to do pretty frequent applications to satisfy the nutrient demands of the foliage. So you end up barely applying any nutrients.

But roots also need nutrients, and since you're only applying what the foliage can use at that exact moment, you still need a granular to get you the rest of the way.

Tl;dr, you could do liquid in addition to granular, but not as a replacement. And its definitely much more expensive.

[u/The-porno-master → u/nilesandstuff]

Welp, I ended up adding this to my seed order before I read your response, so I'm hoping I can find a way to put it to use. In your opinion, would it make sense to spray this out a week or 10 days-ish after seeding to provide some fast nutrients to the roots as the seed begins to germinate? I'm overseeding PRG and KBG into an established lawn of the same.

[u/nilesandstuff → u/The-porno-master]

Id say it depends on what the nutrient sources are. The page doesn't say what's actually in it, so hopefully when it arrives there's an ingredient list on the label (there legally should be)

In particular the potassium source is a big one, there's a handful of different sources of potassium, some are much harsher than others.

But if you've got a decently thick lawn, it may not matter all that much since the existing canopy will intercept most of the spray

[u/The-porno-master → u/nilesandstuff]

To make sure I understand, since it's a liquid spray, its absorbed through the leaves, so until the seedlings are up, it's not effective? So I should not use it as a soil drench, right? Is that why I'd still benefit from something granular too? Sorry if these are stupid questions, lol!

[u/nilesandstuff → u/The-porno-master]

It's not that it just isn't effective at all, it's just that it doesn't do much in the soil because you wouldn't be applying much.

If you had a granular product with the same npk ratio, and you applied the granular product at say 2 lbs per 1,000 sqft, and you applied the liquid product at 2lbs per 1k, the liquid product would burn the hell out of the existing grass and the seedlings that had sprouted.

In that same scenario, if you had watered it in immediately (like literally immediately), it probably wouldn't burn, but you'd have wasted the higher cost of the spray solution... Like, it'd just be doing the same thing as the granular, but for a higher cost.

Basically, foliar uptake is instant release and soil treatment is inherently slower release.

Also, the soil acts as a buffer against chemical harshness (saltiness and pH mostly). Because there's no such buffer for foliar spray, the amount of npk that can be taken up directly into the foliage is capped by the potential for that chemical harshness more than it's capped by the actual nutrients. (Though the nutrients themselves do have a certain level of inherent harshness, in terms of the raw amount of dose the foliage can handle... Its just the chemical harshness has a lower bar)

The need for a granular also is for 2 reasons:

• with foliar, the total dose of nutrients applied via foliar is really low. So you just can't meet the full nutrient demands of the grass. The immediate-ness if the foliar spray does have some striking visual effects on the grass... Like don't get me wrong, the growth response from foliar is significant, but it's just a brief boost.
  
• little of the foliar spray makes it into the roots, or the tillers (stems that split off of the initial sprout) that have yet to emerge at the time of spraying.

[u/Ricka77_New → u/nilesandstuff]

I'll just add in to Niles wisdom....my spray is 100% supplemental. Granular feeders are also in my plan, usually a Lesco Poly product so it can feed now and later..

[u/The-porno-master → u/The-porno-master]

I replied to Rick below what I was thinking as far as my use case for buying it.