Guardian Pre-Emergent Fertilizer

13-0-10 · 0.37% Prodiamine · 50% Slow-Release

Prevent crabgrass and other annual weeds before they start, while feeding your lawn with slow-release nitrogen.

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0.37% ProdiamineProtect your lawn

Keeps turf strong

Supports stronger turf as active growth begins to slow.

Feeds your lawn

Delivers nitrogen and potassium for steady color and nutrition.

Prevents weeds & crabgrass

Helps stop annual bluegrass and other cool-season weeds before they emerge.

Two Benefits, One Application

Feed your lawn and prevent weeds in one easy application, saving time and eliminating the need for separate treatments.

LOCAL SOIL CONDITIONS

Is It the Right Time to Apply?

Check your soil temperature and see when this product is best applied in your area.

5-Day Average Soil Temperature

--°F

Estimated near-surface soil conditions

Current Soil Temperature

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Local modeled reading

Temperature Trend

Compared with recent days

APPLICATION TIMING

Check your local conditions

Enter your ZIP code above to see guidance based on this product's application timing rules and your local soil temperature.

Soil temperatures are estimated using local weather data.

Product comparison

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See the key differences before you buy.

What all options share: 0.37% Prodiamine active ingredient

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Guardian 13-0-10

From $39.99

Best for

Established lawns needing weed prevention and nitrogen feeding during active growth.

Primary benefit

Keeps turf strong — Supports stronger turf as active growth begins to slow.

When to apply

Early spring before crabgrass germinates, or early fall before winter weeds emerge.

Key differences

Nitrogen (N) 13%

Potash (K₂O) 10%

Slow-Release Nitrogen 6.5%

Safeguard 0-0-7

From $39.99

Best for

Lawns needing pre-emergent weed prevention without additional nitrogen or top growth.

Primary benefit

Stops weeds before they start — Prodiamine helps prevent crabgrass, annual bluegrass and other weeds listed on the product label.

When to apply

Before spring crabgrass germination or before fall annual weeds emerge.

Key differences

Nitrogen (N) 0%

Potash (K₂O) 7%

Slow-Release Nitrogen No nitrogen

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Specifications are based on available product information.

0.37% Prodiamine

Helps prevent crabgrass and other listed annual weeds before they emerge.

13% Nitrogen

Promotes healthy growth and green color when your lawn needs feeding.

50% Slow-Release Nitrogen

Half of the nitrogen is slowly available for more gradual, sustained feeding.

10% Potash

Supplies potassium to support turf strength and stress tolerance.

Select Your Grass Type.

Application Rate

4–5 lb per 1,000 sq ft

Equipment

Broadcast Spreader

Apply at the Right Time

Early spring before crabgrass germinates, or early fall before winter weeds emerge.

After Application

Water in with at least 0.5 inch water to activate.

Guaranteed Analysis

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Total Nitrogen (N)13.0%

11.0% Urea Nitrogen†

2.0% Ammoniacal Nitrogen

Soluble Potash (K₂O)10.0%

Sulfur (S)2.8%

Active Ingredient:

0.37% Prodiamine

Derived From:

Urea, Muriate of potash, Polymer coated, sulfur-coated urea, Ammonium sulfate

† 6.5% Slowly Available Nitrogen from polymer-coated, sulfur-coated urea.

Spreader Settings

⌄

Find the right starting setting for your spreader.

Spreader Manufacturer Spreader Model

Select your spreader to see the setting.

Water in after applying

Spreader settings & calibration guide →

Documents & Labels

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Product Label

When should I apply pre-emergent?

Pre-emergent herbicide is best applied before weeds germinate. For cool season lawns, pre-emergent herbicide should be applied before soil temperatures reach 55 degrees consecutively to prevent crabgrass and other weeds.

For warm season lawns, pre-emergent herbicide should be applied in the spring before soil temperatures reach 55 degrees and in the fall, typically in September for season long control

Can I apply it twice?

Yes. A second application 6–8 weeks later helps extend protection. However, refer to the product label for wait times on reseeding and maximum lbs. per year.

Will it stop existing weeds?

No. This product prevents weeds before they emerge.

What weeds does it prevent?

Primarily crabgrass and other annual grassy weeds. Check the product label for a detailed list of weeds prevented.

I applied pre-emergent too late. Now what?

Unfortunately pre-emergents must be applied before weeds germinate. It is very important to apply pre-emergent early before soil temperatures warm up or before coming into the season. You will see additional weed pressure during the growing months that will need to be attended to.

How long do I need to wait until I can seed?

We recommend waiting at least 3-4 months before seeding can take place. Spot seeding can be done if the soil is agitated and or replaced with new soil. Check the product label for exact reseeding intervals based on lbs applied.

Customer Reviews

Overall rating: 4.570513 / 5 from 156 reviews.

AI Generated Review Summary

The Guardian 13-0-10 Pre-Emergent Fertilizer effectively prevents weed germination while promoting steady green growth and deep color in lawns. It is designed for even coverage and dependable performance, with bio-based ingredients supporting soil structure and long-term lawn health.

Summary topics

Lawn Appearance (22%): A significant number of customers loved how their lawn looked after using the Lawn synergy pre-emergent fertilizer.
Product Results (9%): Customers raved about the fantastic and impressive results they achieved with Lawn Synergy's product.
Lawn Aesthetics (12%): Customers expressed satisfaction with how their lawn looks, with many stating that it looks great and amazing.
Grass Health (10%): It was reported by customers that the grass is looking great and has noticeably greener than other areas.
Product Delivery (6%): Customers expressed satisfaction with the quick and easy delivery of the product, which was mentioned multiple times in the reviews.

Review topics: [].

Review highlights

"I have received numerous compliments and questions as to what I'm doing to get my lawn looking so good." — Gordon R.
"With the exception of removing about two dozen overall the lawn looks very well." — ROBERT P.
"My lawn is pretty much weed free and super thick and green." — Gordon R.

Reviews

I just put it down

"I just put it down today. Not sure how long it takes to work! On the downside l received a generic bag from you. Nothing on that says Lawn Synergy. Definitely not a Lawn Synergy bag. How do I know that this 13-0-10, even though the generic plastic bag says it is 13-0-10. Disappointing to say the least. It's probably the real stuff but l will not purchase any more product unless it comes in a Lawn Synergy bag."

— Roger S. (3/5)

I'll let you know in

"I'll let you know in the spring. My zoysia is starting to go dormant already but I haven't had any more weeds since putting this down"

— Shawn S. (3/5)

Didn't notice any difference

"Didn't notice any difference"

— Bill S. (3/5)

"Is to early to put down pre emerging in Georgia on burmudagrass ? I was told that you should do two applications one the fall and one in spring"

— George (5/5)

Seems to do well with

"Seems to do well with the weeds but did not green up like I was expecting."

— Ben G. (4/5)

Made a difference

"This is only my second round of fertilizer and I can see the difference in the thickness of the grass. So far so good. Thank you"

— Dale H. (5/5)

Good Stuff

"Set the tone for next year."

— Andrew J. (4/5)

Very happy with my applications

"Very happy with my applications of 13-0-10. My lawn is pretty much weed free and super thick and green. I have received numerous compliments and questions as to what I'm doing to get my lawn looking so good. I was happy to pass on the name of your company and amazing products. Thank you!"

— Gordon R. (5/5)

Using Lawn Synergy’s subscription service,

"Using Lawn Synergy’s subscription service, I have applied two applications of Guardian thus far and have had spectacular results! Golf course looking lawn with deep green color. I also used their spot weed product Q4 Plus Turf Herbicide periodically and the lawn is almost weed free! Watering regularly and mowing using the highest setting. Summers in NC are tough on tall fescue, so that will be the true test! Highly recommend!"

— RON C. (5/5)

Great looking lawn

"I've cut my front lawn 4 times already and it's due for mowing again tomorrow. This is my second year on the program and I'm very happy with the results. I sent in a soil sample and the fertilizers Tony has recommended have given me a lawn with strong, green blades of grass. ."

— Phil S. (5/5)

Q&A

How soon will I observe the weeds dying, and when can I expect the grass to regain its vibrant green color?: I applied13-0-10 pre-emergent in mid February to hopefully stop weeds from coming up. The second application in mid-April will hopefully **** the weeds that managed to escape the first application.
Hi, does 13-0-10 Guardian Pre-emergent Fertilizer need to immediately be watered in, what's recommended?: It is best to go ahead and water it in, and make sure that you avoid laying it down right before a heavy rain.
Hi, does 13-0-10 Guardian Pre-emergent Fertilizer need to immediately be watered in, what's recommended?: Yes
Hi, does 13-0-10 Guardian Pre-emergent Fertilizer need to immediately be watered in, what’s recommended?: Yes, I did water it in, but I don’t think it was necessary. There was heavy dew in the morning after I applied it, and it dissolved within a few days.
Is this safe for animals after use of this product?: I don't have any animals therefore I don't know if this product is safe for animals.

Three bags of lawn care products from Lawn Envy, including North Star 20-0-10 fertilizer, displayed on a green grass surface against a dark green background.

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