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How To Apply A Split Application with Prodiamine WDG Pre-Emergent Herbicide. Part 1: Costs

by Allyn Hane 30 Jan 2019

Seems this year I’m getting a lot more questions on pre-emergent prodiamine but in regards to liquid application options (water dispersible granule WDG).

I think this is because the community is becoming more advanced, which is awesome. I also think that many of us have been steered to liquids because we enjoy spraying the N-Ext products so much.

Whatever the reason, it’s a topic that I want to provide content about so you can make an informed decision this season on how you are going to carry out your pre-emergent strategy.

Pack A Lunch!

This is going to be one of those VERY long, detailed posting so I broke it into 2 parts. Here is Part 2 if you want to skip right to the "pounds on the ground" for the prodiamine split application strategy. There is a  cool infographic for you to print and literally map out your strategy there as well.

And when I mention “details” I’m not kidding. Lots of math too, because I want you to understand the “why” behind what we are doing. This way you can apply these products properly, safely and within label guidelines.

Now, this is WDG/liquid strategy isn’t something I recommend for beginners. I do however, want you to read, absorb and learn for sure, but don’t go charging into the fire with a squirt gun if you are new.

If you are new then stick to granular. And that brings me to one of the questions I’ve been getting quite a lot this year and that is:


“Which works better; liquid or granular prodiamine applications?”

Answer: making a proper application of granular prodiamine and watering it in will have the very same effectiveness as making a proper application of liquid prodiamine and watering it in.

It’s actually YOU who is the difference maker.

If you are more comfortable with spreading granular products (my preference too) then that stands to reason using granular gives you the best chance at making a proper application. Follow?

Now if your preference is to spray liquids from a hand can or backpack sprayer, then that is the way you should go! Play to your strengths and experience here.

If you happen to have no experience, then take my word for it and stick with granular apps as you are learning. It’s definitely easier to learn with granular products, another reason I recommend using organic fert and letting it fly your first few tries… to learn.

So if you’re ready for granular prodiamine this season, I’ll have that product available for you very soon.

That said, the blog post also gives you all the mix rates and such for liquid apps. This email is going to show you pricing, because that is really the biggest advantage to spraying and praying with your prodiamine as opposed to spreading it dry.

The savings.

Another advantage to liquids is that you have much less chance of a freak storm washing it away. It def gets to the soil quicker. I also like liquid because you can spike in some RGS with it to offer some goodness to the soil at the same time.

How To Apply Prodiamine WDG

I actually purchased a 2-gallon sprayer from Lowes when I was there last week. It’s a decent one in my estimation and I’m going to show you how to get a new sprayer all set up to apply products after performing a bucket test (I’ve done it before here too).

So that video is coming in support of all this content over the next couple weeks. Be sure to subscribe to the YouTube channel if you have not already.

How Much Does Prodiamine WDG Cost?

So let’s do some math here because this is another one of those products that can sticker shock you if you don’t understand what you are actually getting quantity wise. Here’s how it shakes out:

Make sure you get the same stuff I’m using here called Prodiamine 65 WDG (65% active ingredient)

Jug Size:  5 lbs

Cost:       $65.90

Now, I’m going to break this down into a yearly cost for you. Remember, I’m going to give you all the info on “split applications” in the blog post. These numbers take that into account.

In order to figure out the yearly cost we need to know the amount we will put down in a year per 1,000 sq ft.

From there I’m going to use the example of a 5,000 sq ft lawn to give you the total yearly cost and then show you how many years you will get from the 5 lb jug. Ready?


Warm Season Turf (and Turf Type Tall Fescue)

Max Yearly Rate (Calendar Year)

.83 oz/1,000 sq ft

.83 x 5 = 4.15 oz yearly to cover 5,000 sq ft lawn

If you have a 5,000 sq ft lawn then you need 4.15 oz of Prodiamine 65 WDG for the entire year.

That 4.15 oz is going to be split up over the season, not all blown out in a single app - again, check out the blog post for those details.

But from here we can now figure out the yearly cost and more. First, let’s convert pounds to ounces likes this:

1 lb =  16 oz

5 lbs = 80 oz

You get 5 lbs of Prodiamine 65 WDG for $65.90

$65.90/80 = 82 cents per ounce.

The cost of Prodiamine 65 WDG is $.82 per ounce and you only need 4.15 oz of WDG for an entire year!

That means your yearly cost for “liquid prodiamine” is $3.40.

Yes, correct, THREE DOLLARS AND 40 CENTS per year.

Now there is more math because you save money in the long run, and it’s going to be a REALLY LONG run. This 5 lbs of product will cover your 5,000 sq ft lawn for 19 years! Ha ha!

5lbs =  80 oz

80 oz/4.15 oz per year = 19.27 YEARS!!

I hope this also shows you how concentrated this product truly is. Now I’m not trying to scare you here, you can get this product down safely (wear PPE) but I tell you; too heavy and you could do some root damage especially to warm season turf, so be careful and triple check your math.

Additionally, consider that a 2-gallon pump sprayer like the one I have pictured above is really the “minimum viable” way to apply. A battery backpack sprayer would be a much better way to go since it delivers a more consistent spray pattern.

Again, I’m going to do it with a small 2-gallon pump sprayer to show that it can be done but for you (and for me most times) I recommend a better quality battery sprayer for the application (no hose end/jar sprayers).

Kentucky BlueGrass and Perennial Ryegrass (Cool Season)

According to the label, you guys are permitted .55 oz/1,000 sq ft as a yearly maximum. Don’t worry though, I’ve still got a split app strategy for you, all good.

So let’s calculate your cost real quick using the info we got from above: (remember, this is a yearly cost)

5 lbs = 80 oz

Cost: $65.90

$65.90/80 oz = 82 cents per ounce

.55 oz/1,000 sq ft

We have a 5,000 sq ft lawn as our example so:

.55 x 5 = 2.75 oz needed for the year.

2.75 x $.82 = $2.26 per year. CHEAP!


So there you go, as mentioned using the WDG formulation and spraying your prodiamine is much cheaper, but probably a little tougher to get right. Definitely something to consider as you prepare your strategy for this season.

If you are wanting to get a FULL yearly strategy that guides you along during the year as my content unfolds, I encourage you to pick up my warm season or cool season e-books.

These are being updated, but many folks like seeing the “current version” because once we launch the new one the “old one” will be gone forever. That said, there is NOT RISK buying the old one now… because everyone who purchases my e-book, no what version they have, gets lifetime updates.

Every time I update the book, we email you a fresh copy. So go check out the full strategy and then look for the free update in a couple weeks.


If you are in Florida and would like to meet up with me and other members of the lawn care community, consider driving over for the DIY popup meetup in Orlando, Friday, Feb 22 from 5-10PM. There is a cost for this event and there are only 20 spots left.

It’s a 5 hour event with a roundtable and some mingling after. John Perry, Matt Martin, Ryan Knorr, Jake The Lawn Kid, Paul Castleberry, Reel Low Dad, and many lawn pros will be in attendance as well. It’s a great opportunity to come hang out and learn!

Ending Notes:

First, fine fescue, you have a little lower yearly maximum but I’ll tell you this: Fine fescue mostly grows in shaded areas.

Guess what? Crabgrass doesn’t typically thrive in shade. It needs sun to burn up it’s short, miserable year of life and that can’t happen in shade. So in many cases, no need for pre-emergent in the shade.

Second, wonder why tall fescue and the warm season grasses have a greater yearly allowance?

I assume that it’s because you’ll find these grass types in the transition zone and south which those areas have longer growing seasons, so the label accounts for that longer coverage time. Either way, go here now to read the rest of the strategy.


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