Since we started carrying the new 5oz “liquid” prodiamine late last year, one question I’m getting often now is “which is better, liquid or granular prodiamine?”

I’m going to give you a few different reasons why to consider each one, but the short answer is “the best choice is the one that you, the DIYer feel most comfortable applying,” or said another way “the one that you can get down across your lawn the most consistently is the best one to choose.”

I have a comprehensive guide on pre-emergents that is free, download that here.

I say that because prodiamine is a pre-emergent herbicide that stops crabgrass from appearing in the lawn. The way it works is that once you apply and water it in, a vapor barrier is created in the top portion of soil. This vapor barrier remains for several months and as crabgrass seeds germinate and grow the young (very young) plants encounter this vapor which disrupts cell division and effectively stops the the plant from growing. Science is pretty awesome!
granular prodiamine
Some of this below is going to get a little technical - I say that because many of you just want to “throw and go” and if that’s you, just get granular and spread it - that is how the majority of y’all will have the most success. Professional lawn companies across America use both liquid and granular. When it’s early in the season and there is still a chance for a freeze, they use granular, and when things warm up in later spring they switch to liquid. So both do fine, just know that much, but if you want to get into the details and understand the “why” behind my recommendations, keep reading...

How Prodiamine Works

Now just picture a vapor barrier across your lawn. That vapor has to be constant in order to be completely effective. If there are “holes” or spaces where you didn’t get the product down correctly, evenly, consistently; those areas can fail and crabgrass will get through. So first and foremost, choose a prodiamine product that you can apply consistently.

For many DIYers, this will mean granular is the best choice. That’s because the majority of your prefer granular application for everything else - fertilizer, insect control, disease control, all of it. You are comfortable using your spreader and you have gotten good at applying granular products to your land. If that is you, then granular is best.

As you can see in this video demonstration, each pass I make with the granular loaded up, I am throwing product "back to the wheel tracks of the previous pass." What this accomplishes is overlap and that overlap is what ensures a proper application. Overlap is simple to do, and easy to see as you apply.

What About Liquid Prodiamine?

Now, if you are someone who has experience using a pump sprayer or battery sprayer (battery sprayer preferred for consistent flow) then liquid does offer some advantages. First off, just picture the coverage you get with blanket spraying.

Let’s pretend there are no chems involved and you fill your pump sprayer with just water and spray it on your driveway. It will cover 100% of the driveway with water, like painting a wall. Can you picture that?

Now picture putting sand in your spreader and pushing that across the driveway. Sure, that sand will spread out nicely but if you get down and look close there will be space between the grains.

So this is the advantage to liquids - they do cover better/more thoroughly during application. In the case of the Prodiamine 65 WDG we have for liquid, it’s actually a “powder” of sorts known as a “water dispersible granule” which basically means you are createing a very fine particle suspension in water. This is why it’s important to stir it up well upon initial mix and keep it agitated as you go - so the suspension remains consistent.

"That analogy of coverage, liquid vs granular, does this mean liquids are better than granular and get better coverage??"

Answer: they will both work the same if applied according to the label and the most important part there is making a proper application that gets the product down properly.

And that is the key: the rates on the label must be followed. They are important because math has been done to compensate for the variance in coverage between liquid and granular. In other words, granular prodiamine requires much more “pounds on the ground” in order to get the same results as the liquid.

Granular Prodiamine Make Up

The way granular is formulated is that prodiamine powder is bonded to the outside of filler material. In the case of the prodiamine we carry, it’s bonded to limestone and muriate of potash. (that’s why it has a 0-0-7 analysis from the potash)

Our blender, Sunniland, has a math formula they use to tell them how much prodiamine to bond to the grains based on the size and consistency of those grains and the desired application rate. Because I work with DIYers I have our product manufactured so that essentially, 3lb of product per 1,000 sq ft will give you 3 months of pre-emergence protection.

I do this to keep things simple, but I also do it because I try and formulate ALL of our ferts at the 3lbs/1,000 rate so as you utilize my program, things become familiar to you and therefore easier.

So let’s stop right here and think a minute: 3lbs of grains that are coated in prodiamine are spread across 1,000 sq ft of lawn area. That 3lbs will provide that area with about 3 months of pre-emergence protection.

How does this compare to the liquid?

The liquid WDG formulation, also made for me by Sunniland, requires .183 oz/1000 sq ft. (this is on the label)

However, I am going to convert that to grams because that is a more accurate measurement. .183oz = 5.2 g

prodiamine liquid vs granular

What you are seeing in this picture is the literal "pounds on the ground" comparison of two prodiamine formulations that will do exactly the same thing.

Summary Comparison:

3 lbs of granular prodiamine across 1,000 sq ft of lawn space will provide 3 months of pre-emergence protection.

5.2 grams of WDG prodiamine mixed into 1 gallon of water and sprayed evenly across 1,000 sq ft of lawn space will also provide about 3 months of pre-emergence protection.

See how there are a whole lot more granulars/grains/prills needed to cover the 1,000 sq ft area? That is needed in order to ensure that when you water the application in, the powder is washed off the granules and is dispersed throughout the top layers of soil.

With the liquid, you don’t need that because the water acts as the carrier and it’s much easier to cover evenly. However, with the liquid, the walking speed becomes much more important because if you coat the lawn “thin” by walking too fast you can have break through in those areas.

This is one of the reasons that not matter what (liquid or granular) you employ my "split application strategy" which incorporates two applications back-to-back that act like two coats of paint rather than one.

(FYI- the rates I give you here assume you will be doing a split app. Get the pre-emergent guide to understand in detail the split application strategy.)

What About Prodiamine Cost?

One final angle to explore, and an important one, is the cost. This is an easier equation to figure out.

A 45lb bag of granular prodiamine is $54.99 including shipping. That is by far the cheapest you will find it anywhere online shipped directly to your door. That 45 lb bag covers 15,000 sq ft utilizing the rate I recommend is 3 lbs/1000. Each 3lbs/1000 application you make gives you 3 months of pre-emergence protection. I recommend two of these applications in spring, and one in fall (if you are not seeding). 

A 5oz bottle of prodiamine WDG costs $20.48 including shipping. This is the only small bottle of prodiamine WDG found anywhere in the world. The 5oz bottle covers 27,000 sq ft utilizing the 5.2g/1000 rate I recommend. This rate gives you 3 months of pre-emergence protection. I recommend 2 of these applications in spring and another in fall (if you are not seeding)

45lb bag - $54.99 covers 15,000 sq ft

That is a cost of $3.67 per 1,000 sq ft.

5 oz bottle - $20.48 covers 27,000 sq ft

That is a cost of 76 cents per 1,000 sq ft.

The liquid version is MUCH MUCH cheaper. This is why professional lawn companies almost always try to spray their liquid prodiamine rather than apply granular. Chemical cost is their biggest expense besides payroll.

Liquid Pesticides are Less Expensive
You are going to find this is the case with almost all "ides". Ides are my nickname for "pesticides" or what you guys call "chemicals."

Things like this pre-emergent weed control are "ides." Prodiamine is a "herbicide" because it kills plants. 

Other "ides" are "insecticides" and "fungicides" and you will find that in almost every case, getting the liquid concentrate or WDG version that you mix in water and spray is going to be cheaper.

Granular products are just bigger and bulkier so you have to pay for more material to start with, and on top of that, they are more expensive to move around.

Prodiamine DIY vs Hiring Lawn Company

If you are more comfortable using the granular, then that is where you should stay with that because you are still not spending that much money when you compare what a professional would charge you.

If you have a 5,000 sq ft lawn, a professional lawn spray company will charge you anywhere between $40 and $50 to apply prodiamine one time for you. You can get an entire bag for $59.99 that would give your same 5,000 sq ft lawn 3 applications or an entire year of treatments. So for sure, even with granular, the DIY option is still much cheaper than hiring it out.

And lastly, have no fear with prodiamine. If you mess it up, you are not going to hurt anything. If you go too light, you may have some breakthrough and if you go too heavy, it isn’t going to burn your lawn. I don’t want you to go crazy with it on purpose but if you do make a mistake and over apply, non harm will come - you will just get much much longer pre-emergence protection than you need.

The key with all prodiamine is that it has to be watered in - use ½” or irrigation or rainfall as your guide and you’ll be well on your way to a crabgrass free season in 2022.