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How to PREVENT Crabgrass
and Other Weeds in 2024
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By Allyn Hane “The Lawn Care Nut”
www.thelawncarenut.com
Disclaimer
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Disclaimer: This ebook is written for your reference and is not meant to be exhaustive. Everyone’s results vary, but these tips are designed to
get you down the road to success. No matter what, it’s your responsibility to follow safe practices and follow all label instructions from the
products you buy.
In this book, I reference labels. I have done my best to ensure those labels are accurate to the products I recommend. However, labeling
changes - so always be sure to reference the label that is on the exact product you have in your possession.
Introduction
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I give out thousands of free guides about lawn care every
single year. 100% of them are written for DIYers/homeowners
like you. My goal is to help you achieve a thick, healthy, dark
green lawn that is free of weeds.
The thousands upon thousands of seeds that are dropped by
each crabgrass plant carry on the legacy of the mother plant.
If left unchecked, crabgrass can completely destroy your lawn
by out-competing all of your desirable turfgrass.
This guide is arguably the most important of them all because
it’s all about playing defense against crabgrass mostly, but
also against Signalgrass, Poa Annua (annual Bluegrass), and a
few others. But make no mistake, crabgrass is the big one we
are concerned about. It causes the most damage to lawns
across the country.
Crabgrass Life Cycle
In order to defeat crabgrass in the lawn, you first need to
know when those seeds begin to germinate in so you can
stop them!
When it comes to crabgrass, it starts its life in spring, that’s
when the seeds germinate and there is a natural trigger that
tells them when the ideal timing is - that trigger is the
temperature of the soil. When the soil temps in your lawn’s
soil are between 55°F and 70°F in spring, the seeds know it's
time to germinate and begin the seasonal cycle.
It’s a soil temperature window that starts as the snow melts in
early spring and the soil temps rise to around 55°F (crabgrass
window opens) and continues through the mid-to-later
spring as soil temperatures rise to around 80°F (crabgrass
window closes).
What Is Crabgrass?
Crabgrass is an annual grassy weed. “Annual” means the
Crabgrass plant matures and dies during a single season. Its
goal is to germinate, grow, and hit full maturity, then drop
seeds, all within that single season.
When soil temps get over 80°F, it’s too hot, and almost no
more seeds will germinate, but by then, the damage has
already been done.
Introduction
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We all face this problem.
This goes for you up north, across the Midwest, out east,
down south, or out west - you all face the scourge of
crabgrass and this guide is your first step to stopping it for the
2024 season.
New to Lawn Care?
Some of you reading this are pretty new to having to care for
a lawn and you may be feeling overwhelmed at where to start
and how.
Moving into early summer, the seedlings begin to grow and
mature within the canopy of your good turfgrass. You won’t
see them for the most part because they grow wide and flat,
not tall. By late summer, they will begin to push out your
turfgrass in spots and the lime-green appearance will be
quite visible. These flat clumps get larger and larger, dropping
seeds all during the fall, seeding the next season’s crop.
Once you get your first freeze of the winter season, crabgrass
dies and leaves a bare spot that is perfect for the seedlings to
grow in the next year, spreading out further and further.
If that’s you, you are not alone! There is so much information
available online nowadays, it’s hard to tell what applies to you
and your lawn and what doesn’t. This guide talks about
stopping crabgrass. It’s just a small part of the strategy. But
what if you don’t even know the difference between “WarmSeason” vs “Cool-Season” grass? What about fertilizers, biostimulants, weed control, disease control, insects, and seeding
- there are so many pieces to a lawn care strategy, and fitting
them together can be challenging.
On top of all that, you may have some fear about burning
your lawn if you apply something incorrectly.
If any of this is connecting with you, then you for sure will
want to check out the training I created called Yard Care
BootCamp.
Introduction
Yard Care BootCamp is a private video course that will give
you all the basics you need to understand what to put on
your lawn and when. At the end of the course, you will have
the understanding and ability to make proper applications to
your own lawn, both liquid and granular, with no fear.
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Enlist in Yard Care Boot Camp here.
Now, back to the crabgrass and stopping weeds before they
grow content…
2 Types of Weed Control
I have developed this training to get you through your fears
and move you onto success!
The course also includes my 120-page original E-Guide (PDF)
that has sold tens of thousands of copies. I’ve said often that
the E-Guide is like having the cheat codes for the Yard
Mastery app. What’s in that guide is what my app’s logic is
built upon.
Lastly - there is a bulletin board inside Yard Care BootCamp
where you can ask specific questions about your lawn. You
can upload photos too.
In summary, Yard Care Boot Camp breaks down all the barriers
to entry for the DIYer. It’s video training but I also provide the
audio files in MP3 format so you can take them on the road
with you and listen as you commute, like a podcast.
Now you know the window for crabgrass seeds to germinate
and grow starts in the spring as soil temps approach 55°F and
it continues through the spring up to around 80°F. Let’s break
it down a little more.
This guide is all about preventing weeds: playing defense so
that means we need to stop these weeds before they have a
chance to grow.
Pre-Emergent vs Post-Emergent Herbicides
There are 2 types of weed control, pre-emergent and postemergent herbicides.
Pre-emergent herbicides are those talked about in this
guide. Their job is to prevent problem weeds and grasses
from establishing in the lawn. For pre-emergents to work,
they have to be applied and adequately watered into the soil
before weed seeds germinate.
Pre-Emergent for Crabgrass
Post-emergent Herbicides are products that are applied to
weeds that have already come up and started to take hold in
the lawn. Think of post-emergents as “corrective” rather than
“preventative”. These do not prevent weeds, but instead, kill
them where they stand. Most post-emergent herbicides do
not offer any long-lasting preventative protection. Their
effectiveness wears off within days or even hours.
Pre-Emergent for Crabgrass - Strategy and Approach
Next, I want to set your expectations properly when it comes
to pre-emergent herbicides and applications. First, you can’t
prevent most lawn weeds, especially broadleaf weeds - there
is no pre-emergent for them.
Clover, Dandelions, ground ivy (Creeping Charlie), Dollar
Weed, Plantain, Dockweed, Wild Violet, Dayflower - and many
other broadleaf weeds - have no preventative herbicide
available for them.
I stress this because I want you to understand that preemergent applications are only one piece of an overall lawn
strategy. It’s an important piece for sure, because as illustrated
above, crabgrass can mess up your lawn, but it’s not going to
solve all of your weed problems.
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If you’ve overall had a bad weed problem in the past, you’ll
need to be prepared to employ a good post-emergent weed
control strategy during the season as well.
Here is a video I made last year showing you some of the
post-emergent weed killers available at your local big box
store or Ace Hardware:
Pre-Emergent for Crabgrass
Nature Is Undefeated
Next, know that the weather always wins and some years are
better than others. The pre-emergent weed control I
recommend below is used by professional lawn services all
over the country. It’s the gold standard and has been proven
to work very well against crabgrass over the last 30 years. But
some years the weather throws a curveball at us.
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Even in perfect seasons, you’ll almost always get some
breakthrough around the edges of the driveway and
sidewalks because the radiating heat off the concrete breaks
down the pre-emergent barrier. That’s why when you do see
crabgrass break out in a lawn, you almost always see it around
the edges of the lawn first.
When you apply pre-emergent and water it in, the chemical
exists and persists as a vapor barrier right at the soil surface.
You can’t see it visibly, but it’s there, and depending on how
heavy you apply (your application rate), it can last for months,
but that assumes perfect conditions. As I’m sure you know,
the weather is variable from year to year.
For example, an extremely wet spring and summer can
shorten the effectiveness of the chemical by washing it out
prematurely. On the flip side, a drought where the soil dries
out for long periods of time will do the same because the sun
degrades it.
In “bad weather” seasons, even if you make a perfect
application within the perfect timing, you may still get some
breakthrough of crabgrass. We are working with living things
and are at the mercy of the weather - lawn care doesn’t
happen inside a laboratory.
So as you progress through the 2024 lawn season, keep in
mind the key to a weed-free lawn is a very strong preemergent game, and a strategic, targeted post-emergent
game to catch the escapees.
Fertilization, watering, and proper mowing are also important
to increase the density of your good turf as a thick lawn is also
an excellent defensive weapon against invading weeds.
Pre-Emergent for Crabgrass
Download my FREE app called “Yard Mastery” and it will give
you a year-long program for your lawn. All of the logic is built
off of soil temperatures and it’s accurate down to the
neighborhood level. Get the app free, here.
With a consistent strategy employing all the tools mentioned
above, over time, you can eliminate crabgrass almost
completely in your lawn and, therefore not need preemergent weed controls thereafter.
I covered that topic in detail on the podcast not long ago This short video is a good one to review.
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Active Ingredient - What To Apply To Stop Crabgrass
You’re now armed with the basic approach to stopping
crabgrass using pre-emergent herbicides, but what actual
“chemical” is recommended? This is where the “active
ingredient” becomes important.
There aren’t too many pre-emergent herbicides available but
the ones we have are time-tested and proven. For
homeowners, the best active ingredient to utilize in your
strategy is called “Prodiamine". It’s classified as a group 3
herbicide and the way it works is to disrupt cell division in
newly germinated plants, stunting them to the point of
death.
If you are someone who likes to go deep in your research and
understand the “why” behind my recommendations, this blog
post is for you. It talks about the chemical class (mode of
action) of Prodiamine and how it works at a molecular level.
Read that post here.
Prodiamine
We have Prodiamine available in two different formulations:
granular and liquid.
Granular Prodiamine
The granular is by far the easiest for homeowners because
you just dump it in your spreader, set it (settings in this
guide), and go push. It works great and is easy to apply.
W
We have 45 lb bags
available that cover 15,000
sq ft, and here in 2024, as
many of you requested,
we released a smaller 18 lb
bag that covers up to
6,000 sq ft.
You make your application
and water it in with a
minimum of 1/2” of
irrigation or rainfall and
you’re good to go!
Note: We switched suppliers for the 2024 season which
allowed us to get that 18 lb smaller bag. If you have
purchased in the past, the bag and label will look different
but what’s in the bag is the same. So are the application rates.
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Prodiamine
Liquid Prodiamine
We also have a formulation called “WG” which stands for
“wettable granule.” This is more like a powder form that when
mixed in water in a sprayer makes a liquid you can spray out
and apply. Years ago the only WG powder available was a 5 lb
jug that could cover several acres of turf. It was made for
professionals only and if you were a DIYer wanting this
product you’d have to buy that jug and store it, and probably
never use the entire thing across your whole lifetime.
Yard Mastery worked with a supplier to get Prodiamine
packaged in a much smaller bottle which is better for
homeowners. It’s just 5oz which is sized for smaller lawns.
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Here are some frequently asked questions I get when it
comes to Prodiamine:
1. Which is better, liquid or granular? The short answer is
they both work the same so what matters is which one
you can make a proper application with. If you are more
confident with granular, go that way. If you are more
confident with liquids, then go that route. Here is a
detailed blog post on the subject.
2. Can I seed the lawn in spring if I use Prodiamine? Short
answer: no. As always, much more detail here in this blog
post.
3. When is it too late to apply Prodiamine? Pretty much
when soil temps pass 75°F there is no need to apply as
it’s too late, but anytime before that is a good idea. Here
is a blog post going into that thinking.
4. Are lawn chemicals safe? The answer is that if you follow
the labeled directions, you should be just fine! Detailed
blog post here.
Also, if you need a good sprayer, this is the best one on the
market in my opinion.
Note: WG needs to be applied via battery/pump sprayer, not
hose-end sprayer.
5. Which one costs more? For this, I want to break it down
in some more detail for you because I think you will be
surprised at just how cheap it is to treat your own lawn
with pre-emergent herbicide Prodiamine. There’s a
complete section below showing you all the math and
costs.
Prodiamine Application Timing
Are you ready to get out there and make your applications? I
recommend 2 applications in the spring and another one in
the fall time (if you are not seeding.)
Here is how they break down:
Application #1
SPRING: As soil temps cross 50°F heading to 55°F, apply
Prodiamine.
Application #2
SPRING: As soil temps cross 65°F heading to 70°F, apply
Prodiamine.
Application #3 (optional)
FALL: As soil temps fall to 70°F coming out of summer, apply
Dithiopyr or Prodiamine.
• You can pick up Prodiamine granular right here
(18 and 45 lb bags)
• You can pick up the WG for liquid Prodiamine right here.
Spreader Settings for 3lbs/1,000 sq ft (3 months coverage)
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Where To Get Soil Temperatures
You can get soil temperatures for your home by downloading
my FREE app called Yard Mastery. Not only will you have your
exact soil temperatures whenever you need them, you’ll also
get custom recommendations for fertilizers and biostimulants based around those temps as well.
There is also a journal section where you can track your
progress and a whole lot more! Download the app here, it’s
free.
The next page is an infographic that shows you the strategy
laid out in simple terms.
Strategy Breakdown
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thelawncarenut.com
Analysis Paralysis
Now there is a little bit of nuance in the application strategy
when it comes to “cool-season” lawns vs “warm-season” lawns.
It’s mainly because warm-season grasses (Bermuda, St
Augustine, Centipede, Zoysia, Bahia) have a longer growing
season than cool-season lawns (Perennial Rye, Kentucky
bluegrass, tall fescue).
Analysis Paralysis
Let’s pause right here. For many of you, the information above
is enough and you’re ready to go. If you go into much more
detail, you’re going to get overwhelmed with too much
information too fast. I know because I hear this all the time.
If that is you, then just skim the rest of the ebook here. I’m
going to go into quite a bit more detail and break down
what’s on the label and explain why and what it all means.
Some of you will appreciate this level of detail, others it will
completely cause you to freeze up.
If you’re the type that doesn’t need any more detail, then
download my app here (free) and it will tell you when to
apply your Prodiamine so you get it down right. You’ll be
good to go, no worries and you won’t have to concern
yourself with all the details ahead.
But for those of you who would like to learn more, let’s break
it down by grass type “cool-season” vs “warm-season”.
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Pre-Emergent in Cool Season Lawns
Cool Season Grass Types
• Kentucky Blue Grass
• Perennial Rye
• Turf Type Tall Fescue
How Prodiamine Helps Cool Season Lawns
We have already talked about crabgrass, an annual that
germinates in spring, rages all summer, and drops seed in fall,
but there are other weeds that Prodiamine will also help you
with.
Let’s start with 2 other common spring annual grassy weeds:
Foxtails - Similar to Crabgrass, this weed germinates in spring,
and rages all summer and into fall time. You can easily spot
these in later summer because of their distinctive seed heads,
which are why they got their name. Prodiamine works pretty
well on foxtails.
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Barnyardgrass - Another spring annual that lives a similar life
cycle to crabgrass. Here is a video from the University of
Illinois showing you how to identify it.
If you are not seeding in the fall time, then an application of preemergent will help with these fall germinating annuals:
Poa-Annua (Annual Bluegrass) - Poa-Annua germinates in fall,
some also in very early spring, and drops seeds the following
spring. Applying an application of Prodiamine in the fall will
greatly reduce and/or eliminate it.
Henbit - This one gets confused with creeping Charlie
because of its purple flowers. You really won’t notice it too
much in fall when it first starts to grow - it’s the following
spring that it REALLY shows up. Watch this video here to see
me ID it for you in a cool season lawn in NW Indiana.
Pre-Emergent in Cool Season Lawns
Hairy Bittercress - Similar to Henbit, this one starts in fall but
you won’t notice it until the following spring when it grows
tall and pushes out white flowers. Bittercress grows as far
north as Chicago, and as far south as Florida. It’s everywhere
but is most heavily concentrated further south.
Chickweed - This weed can germinate pretty much anytime
during the season but it’s classified as a fall annual.
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Here is a full list from the label of Prodiamine showing all of
the weeds it works on:
Pre-Emergent in Cool Season Lawns
How Much Granular Prodiamine To Apply
Now when it comes to the rate of application for cool-season
lawns and granular Prodiamine, we need to look at the label. I
encourage you to read the labels on all of the lawn products
you purchase. I promise if you take the time to read them, you
will learn something. I read these same labels on products
every year when I re-write my e-books and I learn something
every time. If you lack the confidence to make lawn
applications right now, then the first thing you can do to gain
some is to read the label on the product.
For Prodiamine we are first going to key in on the yearly
maximum “pounds on the ground.” The herbicide Prodiamine
has some rules around how much you can apply in a single
calendar year. You do not want to exceed that amount. If you
do, it’s not necessarily going to hurt anything - but you still
want to follow the label. The label is the law and the
limitations are there for good reason. Usually, it’s to help with
resistance management. Often, if too much of a chemical
class (mode of action) is introduced, plants can begin to build
a resistance. That’s just one reason why some chems are
limited like that. Whatever the reason though, it’s always your
responsibility as a land-owner to follow the label to the best
of your ability.
Now, don’t be scared, keep reading!
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These screenshots are from the label on the Prodiamine that I
carry on my websites here.
Pre-Emergent in Cool Season Lawns
This section is about cool-season grasses so I have circled the
3 most common cool-season turfgrass species in the US. Your
lawn is likely a mix of 2 or even all 3 of these. One of the most
common mixes in big box store grass seed is a combination of
Perennial Ryegrass and Kentucky Bluegrass.
99% of you reading this will not know if your lawn is Fescue,
Ryegrass, or Kentucky Bluegrass. They all look very similar. I
will tell you that most of the turf-type Tall Fescue lawns are in
the middle of the country, what we call “the transition zone”
and the further north you go you run into more Kentucky
Bluegrass and Ryegrass mixed lawns.
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That’s a very generalized analysis so take it for what it’s worth,
but it makes sense with the logic of these application
maximums. You can see on the chart that the maximum
“pounds on the ground” of this Prodiamine product is 6.2 lbs/
year if you have Kentucky Bluegrass or perennial ryegrass and
9.3 lbs/year if you have Tall Fescue as your turf type.
Since turf-type Tall Fescue is mostly grown in the middle of
the country, the growing season is longer so they allow you
more “pounds on the ground” to help mitigate weeds longer.
Pounds On The Ground
Now here’s the thing: you can divide up those “pounds on the
ground” however you prefer as long as you do not exceed the
yearly max. So let’s pretend you have a Kentucky Bluegrass
lawn and you are going to make your applications in spring to
stop crabgrass.
You are allowed 6.2 lbs/year of the product. You could do all
6.2 lbs in one application in the spring and you’d get 6
months of protection against crabgrass. That’s how it works.
For every pound of product applied, you get about 30 days of
protection (give or take).
Pre-Emergent in Cool Season Lawns
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But I don’t do it that way. In the strategies that I teach, I
recommend what is called a “split application” strategy where
we apply 3lbs/1,000 in early spring (soil temps crossing 50°F 55°F) and a second application of 3 lbs/1,000 in later spring
(soil temps crossing 60°- 65°F).
Kentucky Bluegrass and Rye Grass
Now with KBG and Ryegrass, you have that 6 lbs/1,000 yearly
max rate (refer to chart) and you use it all up in the spring.
What if you need to do a fall application to stop Poa Annua,
Henbit, and Bittercress? You’ve used it all up!
I run it this way because it gives you some overlap in case of
mistakes or freak weather. You get the same 6 months of total
protection, but it’s spread across 2 apps instead of 1.
That is why we carry a second option of pre-emergent called
“Dithiopyr.” That is the active ingredient name. It works just as
well as Prodiamine and is what you use in the fall if you have
one or both of those grass types, (and you are not seeding the
lawn).
Think of it like painting. If you apply 2 coats of paint you likely
will have a better overall even and consistent coverage vs just
applying a single coat of paint that is thicker.
By doing “split applications” you are just adding a little safety
net for yourself.
It’s not uncommon for someone new and inexperienced to
miss some spots when they apply. By doing 2 split
applications, you help to mitigate these mistakes. You also
may have an area that gets a lot of foot traffic from pets or
people and the vapor barrier can be degraded from that. By
doing the two applications you get a little more overlap and
protection in that case also.
Professional lawn companies do the same thing, that's where I
learned that approach in the first place. (I worked for
ChemLawn in Chicago for 15 years when I was younger).
Turf Type Tall Fescue
If you have turf-type Tall Fescue, you get 9 lbs/yearly for your
lawn. You will do the same 3 lbs/1,000 twice in spring and you
then will have an additional 3 lbs you can utilize in the fall for
an application then. That’s really the only difference in the
strategy. You will not need to utilize the alternative preemergent Dithiopyr at all.
What If I’m Not Sure?
This comes up often because as I mentioned before, most of
you will have no idea whether you have KBG, Ryegrass,
Fescue, or a mix of them. In that case, just use the KBG/
Ryegrass rates and you will be fine - it’s still 3 lbs/1,000 in early
spring and another 3 lbs/1,000 in later spring. If you are not
aerating and/or overseeding in the fall, then you just use
Dithiopyr as your fall treatment option. All good!
Pre-Emergent in Cool Season Lawns
Measure Your Lawn
Now did you notice that the yearly maximums are broken
down into 1,000 sq ft increments? In lawn care, we talk in terms
of 1,000 sq ft. Every product you buy will have coverage
amounts listed and they will always be broken down into 1,000
sq ft increments. Here is a video where I teach you how to
measure your lawn and break it down into these increments.
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You can also measure your lawn inside my Yard Mastery app.
Now that we’ve gone to that level of detail on the label and
you understand how much to apply, let’s once again look at
the pre-emergent strategy for the season. Remember, it’s 3
total applications, 2 spring and 1 fall (if not seeding).
Pre-Emergent Application Rates and Timing:
(Cool Season Turf )
• Step 1 - Early/Mid Spring when soil temps cross 50°F
heading to 55°F Prodiamine - 3 lbs/1,000 sq ft.
• Step 2 - about 35-45 days later when soil temps cross 65°F
heading to 70° F - Prodiamine - 3 lbs/1,000 sq ft.
• Step 3 - Early Fall when soil temps approach/fall to 70°F Dithiopyr - 4 lbs/1,000 sq ft (if you plan to seed the lawn,
skip this step).
If you want the application rates for the WG for liquid, here is
a full page showing you how much to apply.
IMPORTANT: All pre-emergent applications need to be
watered in to work. Get them watered in within 48 hours of
application if you can. The sun can degrade the chemical so
get it watered in ASAP.
How Much Does All This Cost?
Granular Applications
Each application we do will be 3 lbs/1,000 sq. ft. That means
that you will use your broadcast spreader to apply 3 lbs of
granules across each 1,000 sq. ft. of lawn space. Let’s run some
math then:
45 lb Granular Prodiamine
Bag Cost: $59.99 (includes shipping)
Bag Size: 45 lbs
Cost per Pound: $1.33
App Rate: 3 lbs/1,000 sq ft
Cost per 1,000 sq ft: $3.99
If you have a 5,000 sq ft lawn,
then each application of
pre-emergent will cost
you $19.95.
Not too bad, eh?
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Liquid Applications - Water Dispersible Granule
For those of you who want to spray your application, let me
break down the math for you, too:
5oz Prodiamine
Bottle Cost: $29.99
Size: 5 oz bottle
App Rate: .183 oz/5.2g per 1,000 sq ft
5 oz = 142 grams (we used grams
because this product must be weighed)
142/5.2 = 27.3
This bottle can cover 27,300 sq ft
at the rate of 5.2g/1,000 sq ft
Cost per 1,000: $1.09
Example Lawn Size: 5,000 sq. ft.
Cost per application: $5.45
This is one of the true advantages of doing your own lawn care!
It’s also why I am always trying to break the math down for you.
This is much cheaper than granular so if you can spray liquids,
this is for sure the most economical way to go. Here are more
detailed instructions.
I want you to understand that doing your own lawn is pretty
cheap. Sure, you have to invest money upfront in a big bag,
but when you break it down, for your 5,000 sq ft lawn, you
can get 3 full applications out of that 1 bag.
65WG needs to be applied via battery/pump sprayer, not
hose-end sprayer. Here is the Yard Mastery backpack sprayer
that is the best on the market.
Advice: If you are a beginner and this is confusing you,
use GRANULAR! It’s easier.
Warm Season Grass Types
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The other challenge we have is that in most cases, the soil in
our region never freezes. That means weeds germinate yearround even when southern lawns are dormant in winter.
There is no overseeding of warm-season lawns in fall either so
we end up with a year-round strategy.
Thanks for hanging in there my warm-season friends! Your
pre-emergent journey is actually much more urgent because
things warm up for you much sooner!
In the south, we have the same challenges with crabgrass,
Henbit, Bittercress, and Poa-Annua. But we also have the
added challenges of:
• Pusley
• Spurge
• Woodsorrel (oxalis)
The photo here is of Hairy Bittercress in my lawn in February. I did
not apply a pre-emergent the preceding fall.
So in the south, these are the warm-season grasses we are
working with:
• Centipede
• St Augustine
• Bahia
• Bermuda
• Zoysia
Warm Season Grass Types
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Warm Season Grass Types
This is one of those rare cases where we can use the same
“chemical” in our warm-season lawns that they use up north
in the cool-season lawns. You already know this chemical is an
active ingredient called “Prodiamine.”
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On the label, you can see that warm season grasses are
permitted a yearly maximum of 9.3 “pounds on the ground”.
The herbicide Prodiamine has some rules around how much
you can apply within the calendar year. You do not want to
exceed that amount. If you do, it’s not necessarily going to
hurt anything - but you still want to follow the label. The label
is the law and the limitations are there for good reason.
Usually, it’s to help with resistance management. Often, if too
much of a chemical class (mode of action) is introduced,
plants can begin to build a resistance. That’s just one reason
why some chems are limited like that. Whatever the reason
though, it’s always your responsibility as a land owner to
follow the label to the best of your ability.
Pounds On The Ground
Now here’s the thing: you can divide up those “pounds on the
ground” however you prefer as long as you do not exceed the
yearly max.
This section is about warm-season lawns.
You are allowed 9.3 lbs/year of the product. I round down to 9
for easy math. You could do all 9 lbs in one application in the
spring and you’d get 9 months of protection against
crabgrass. That’s how it works. For every pound of product
applied, you get about 30 days of protection, (give or take).
Warm Season Grass Types
But I don’t do it that way. In the strategies that I teach, I
recommend what is called a “split applications” strategy
where we apply 3 lbs/1,000 in early spring (soil temps
crossing 50°F - 50°F) and a second application of 3 lbs/1,000
in later spring (soil temps crossing 65°F). That gives you 6
months of protection from spring into summer.
Then we have an additional 3 lbs/1,000 leftover for a fall
application, which gives us 3 months from late summer into
fall and winter.
I choose to break things up into 2 apps in spring because it
gives you some overlap in case of mistakes or freak weather.
Think of it like painting. If you apply 2 coats of paint you will
likely have a better overall, even, and consistent coverage vs
just applying a single coat of paint that is thicker.
By doing “split applications” you are just adding a little safety
net for yourself.
It’s not uncommon for someone new and inexperienced to
miss some spots when they apply. By doing 2 split
applications, you help to mitigate these mistakes. You also
may have an area that gets a lot of foot traffic from pets or
people and the vapor barrier can be degraded from that. By
doing the two applications you get a little more overlap and
protection in that case also.
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After these 3 applications, you are maxed out on Prodiamine.
Some of you in far south Texas, down along the Gulf Coast,
and into Florida may need even longer protection and that is
why we have an alternative active ingredient called
“Dithiopyr.” It works the same as Prodiamine but offers some
extended flexibility if you have maxed out your Prodiamine
and still need more coverage.
Pre-Emergent Application Timing: (Warm-Season Turf )
• Step 1 - When soil temps cross 50°F heading to 55°F Prodiamine - 3 lbs/1,000 sq ft
• Step 2 - When soil temps cross 65°F heading to 70°F Prodiamine - 3 lbs/1,000 sq ft
• Step 3 - When soil temps begin to fall below 70°F Prodiamine - 3 lbs/1,000 sq ft
• Step 4 - If soil temps stay over 55°F during winter Dithiopyr - 4 lbs/1,000 sq ft
If you want to see a cost breakdown, review the cool-season
lawn section on page 21.
IMPORTANT: All pre-emergent applications need to be
watered into work. Get them watered in within 48 hours of
application if you can. The sun can degrade the chemical so
get it watered in ASAP.
Conclusion
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There you go folks - I hope this was helpful. If you like this
type of long-form content, please let me know by hitting me
up on Twitter or Facebook. If you are looking for a full-season
lawn plan, be sure to download my app, it’s free!
Also, please feel free to forward this to a friend, especially a
neighbor! One of the best ways to help keep weed problems
out of your lawn is to have neighbors around you who also
keep weeds out of theirs!
Lastly, please wear proper personal protective equipment
(eye protection, gloves, long sleeves, etc.) as listed on the
label of each product you buy. Never take your safety for
granted. Also, sunblock. Protect your skin from the sun. No
joke.
I’ll see YOU in the lawn,