Which is Better: Granular or Liquid Prodiamine?

Since we started carrying the new 5oz “liquid” prodiamine a couple-two-tree years ago, one question that I get in our Facebook Group is often now is “which is better, liquid or granular prodiamine?”

If you’re not familiar, here is everything you need to know about how prodiamine works to stop crabgrass, signalgrass, goosegrass and foxtail.

I’m going to give you a few different reasons why to consider each formulation, granular prodiamine that you spread, or WDG “powder” that you mix in water to spray.

Up front, and to be perfectly clear, 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 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

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 (don’t want spray lines freezing up), they use granular, and when things warm up in later spring they switch to liquid. So both do fine, 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 you 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.

With granular prodiamine, the prills are coated with a fine powder of prodiamine. It sticks to them. When you spread them in the lawn evenly and then “water it in” the powder washes off the prills and into the soil and spreads out, making the barrier.

The key with granular is overlap. When you apply with your broadcast spreader, you throw product back to the wheel tracks of the previous pass. This overlap is what ensures good coverage throughout the application process. It’s an easy process to learn and once you’ve done it 2-3 times on your own property, it becomes second nature.

What About Liquid Prodiamine?

Now, if you are someone who has experience using a pump sprayer or battery backpack 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 creating 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.

The overlap when spraying liquids is “tip to tip” meaning you just kiss the edge of the previous pass. There can be error here in between rows if you are not paying attention as you walk and apply. Also if you walk too fast you can have inconsistent application. You can essentially “out run” the flow rate of the equipment. (watch video on calibrating sprayer here)

“So then which one works better? Powder washing off grains and dispersing in the soil (granular) or liquid being sprayed on the lawn ?”

Answer: they will both work the same if applied according to the label and the most important part there is making a quality 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 experience break through in those areas.

This is one of the reasons that no 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.)

Lawn Care Nut Strategy – Coverage

Something else to notice is that the 45lb bag of prodiamine is enough for 3 applications on a 5,000 sq ft lawn. (using my strategies)

The 5oz bottle of prodiamine is enough for 3 applications per year on a 9,000 sq ft lawn. (using my strategies)

Remember, my strategy calls for 2 applications in spring and 1 application in fall (if not seeding).

Granular Prodiamine Math (you love this!)

Bag weight 45lbs
Application rate: 3lbs/1000 (my strategies)
Coverage: 15,000 sq ft
45/3 = 15
#apps per year: 3 (2 spring, 1 late summer/fall)

15,000 / 3 apps per year = 5,000 sq ft per application.

(spring) Application 1 (as soil temps cross 50-55F)
15 lbs covers 5,000 sq ft

(spring) Application 2 (as soil temps cross 60-65F)
15 lbs covers 5,000 sq ft

(late summer) Application 3 (as soil temps fall to 70F)
15 lbs covers 5,000 sq ft

15 x 3 = 45 lbs total

If you have a 2,500 sq ft lawn, then you can get 2 years out of 1 bag. Keep it dry and it will be fine.

Liquid Prodiamine Math (you gotta love it!)

5oz prodiamine = 141.7 grams
Application Rate: 5.2 grams / 1,000 sq ft
141.7 / 5.2 = 27.25
27.25 / 3 applications = 9,000 sq ft
(I did some rounding to make the math easy)

So if you have a 9,000 sq ft lawn, you can perform 3 applications per year (2 spring, 1 fall) and use up the entire bottle.

(spring) Application 1 (as soil temps cross 50-55F)
5.2g x 9 = 46.8 grams

(spring) Application 2 (as soil temps cross 60-65F)
5.2g x 9 = 46.8 grams

(late summer) Application 3 (as soil temps fall to 70F)
5.2g x 9 = 46.8 grams

46.8 x 3 = 140.4
(close enough with rounding)

If you have a 4,500 sq ft lawn, you can get 2 years out of the bottle.

What About Prodiamine Cost?

So far we know that the 5oz bottle of prodiamine will cover more square footage than a 45lb bag.
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 $59.99 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. (repetition is the key to learning!)

A 5oz bottle of prodiamine WDG costs $24.48 including shipping. The 5oz bottle covers 27,000 sq ft utilizing the 5.2g/1000 rate I recommend.
(repetition is the key to learning!)

45lb bag – $59.99 covers 15,000 sq ft

That is a cost of $3.99 per 1,000 sq ft.

5 oz bottle – $24.48 covers 27,000 sq ft

That is a cost of 91 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.

So it comes down to this:
Are you more comfortable with granular applications? If so, you have a higher cost for that comfort.

Are you more budget conscious, then you’ll learn to spray liquids to save the money!

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.”

When it comes to pesticides, applying them via liquid is always cheaper because you don’t have the cost of the carrier material. In prodiamine the carrier material is calcium carbonate and a little bit of potash.

In granular Hydretain, the carrier is chicken compost. There are many other examples. So just know, liquid is always cheaper with the “ides”

Note: it is not always this way with fertilizers, I’ll do some blog posts on that coming up!

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 $60 and $70 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 2023.