Princep Liquid Herbicide
Princep Liquid Herbicide

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Average Rating

4 out of 5 stars Rating: 4.1

11 Reviews | 71 Q&A

Product Overview

Princep Liquid Herbicide works as a pre-emergent herbicide used to prevent a variety of grass and broadleaf weeds such as crabgrass, groundsel, goosegrass, and many more (see label for complete details). Use Princep Liquid Herbicide before weeds emerge or after already emerged weeds have been removed. With a variety of use sites Princep Liquid Herbicide is a versatile product that can be used on commercial and residential turf (Warm Season grasses only), nurseries, Christmas trees, shelter belts, and sod farms (only in Florida).

Note: Due to New California State restrictions, this Can Not be Sold in California.


Features and Specs

Active Ingredient Simazine 41.9%
Target pests A wide variety of annual broadleaf and grass weeds, including crabgrass, goosegrass and groundsel and many others
* See label for complete list
For use in Golf courses, residential and commercial lawns (Warm Season grasses only), nurseries, commercial landscapes and ornamental plantings (when tank mixed only), Christmas tree plantings, sod farms (Florida only), and shelter belts
* See label for complete list and instructions
Application * See label for complete application instructions
Pet safe Yes, if used as directed on Label
Formulation Professional Product
Group 5 Herbicide
CA, NY, VT (Restricted To Licensed Applicators Only)
Shipping Weight 24.74 lbs
Manufacturer Syngenta (Mfg. Number: 59200)
EPA Registration 100-526


When tank mixing or sequentially applying simazine or products containing simazine, the total pounds of simazine applied must not exceed the specific maximum rate per calendar year as noted in the use directions.

Apply Princep Liquid before weeds emerge or after removal of weed growth. Princep Liquid controls a wide variety of annual broadleaf and grass weeds when used at selective rates in turf and ornamental plantings.

Where a range of application rates is given, use the low rate on coarse-textured soil and soil lower in organic matter; use the high rate on fine-textured soil and soil higher in organic matter.

Since Princep Liquid enters weeds mainly through their roots, moisture is needed to move it into the root zone. Very dry soil conditions following application may necessitate shallow cultivation or rotary hoeing.

  • For use in a broad range of areas
  • Controls a wide variety of broadleaf and grass weeds

WARNING: This product can expose you to chemicals including simazine, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to

Review Search   
Sort Reviews
  • 5 of 5 Stars

    Very Effective

    By Tom on 08/21/2015

    I have used Princep in every form available for over 25 years because it works and the product I bought here is equally effective. Great for parking lot cracks, fence lines and areas where no growth is wanted. Using the highest labeled rate works fine in these places.

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    27 of 30 people found this review helpful

  • 5 of 5 Stars


    By Paul on 11/15/2014

    Verified Purchase

    I use this with a hand sprayer to keep weeds from my driveway and fences. This liquid product is a lot easier to use than the dry product I have used in the past. I have not tried it in my lawn yet

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    17 of 23 people found this review helpful

  • 5 of 5 Stars

    Princep Post emergent Qualities

    By Bill on 12/09/2019

    Put down Princep about 3 weeks ago and have had surprisingly good results with post ermget knock down of annual bluegrass as well as some clovers and Parsley - Piert. Will do a follow up at the start of spring for full performance.

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    9 of 10 people found this review helpful

  • 4 of 5 Stars

    Princep Liquid

    By Frank on 01/25/2015

    Verified Purchase

    Very easy to apply. Hopefully it will work as well or better that the Princep powder that I used previously

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    7 of 15 people found this review helpful

  • 5 of 5 Stars

    Great product

    By Lynn on 09/04/2020

    Great product !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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    3 of 6 people found this review helpful

See all 11 customer reviews

Questions & Answers

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Sort Questions
How do I mix Princep Liquid Herbicide with water (per gallon) to spray my lawn? I will use a one gallon sprayer.

You will need to use 0.75-1.5 fl. oz./1,000 sq. ft depending on your target weed. Most folks use the higher usage rate.

The first thing you need to know when using an herbicide such as Princep Herbicide is that the exact amount of water you dilute it with is not important. It is only important to make sure you are using the correct amount of product per 1,000 sq ft of lawn. Use too much and you risk damaging your lawn, use too little and you will not get adequate results. You will need to use 0.75-1.5 fl. oz per 1,000 sq ft . To decide how much water you want to use, you should mark a 1,000 sq ft area, fill your sprayer with WATER ONLY, and start walking and spraying just as if you were doing the actual application of herbicide. When you are done walking and spraying the 1,000 sq ft area note how much water it took you to spray that area, and that is the amount you will want to mix 0.75-1.5 fl. oz of product with for each 1,000 sq ft area that needs to be treated.

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114 of 144 people found this answer helpful

What is the coverage area that one jug of Princep Liquid Herbicide will treat?

One 2.5 gallon jug of Princep Liquid Herbicide can cover 5-10 acres depending on the usage (1-2 qt per acre) rate needed for your use.

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76 of 85 people found this answer helpful

How long will Princep Liquid Herbicide stay in the soil?

It was applied to an area last spring and would like to place a few plants in the same area.


If Princep was applied a year ago, you should be fine to plant or seed the area now. Generally, you would wait between 4-6 months.

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51 of 53 people found this answer helpful

What is the proper mixture for Princep Liquid Herbicide?

I followed the 1 oz per 1000 sq feet and it did not touch the weeds in my yard.


Princep Liquid Herbicide is a pre-emergent weed control product and it will not control the weeds that have already emerged in your yard. According to the Princep product label: Apply Princep Liquid after September 1 (after October 1 for annual bluegrass) before emergence of winter annual weeds. Fall applications of Princep Liquid will control annual bluegrass, burclover, lawn burweed, common and mouseear chickweed, corn speedwell, henbit, hop clover, spurweed, and parsley-piert. Princep Liquid will also control these weeds soon after emergence. For control of summer annual weeds listed in the Product Information section of this label, apply Princep Liquid in late winter before the weeds emerge. Apply in a minimum of 15 gallons of water per acre. Irrigate with 1/2 inch of water if rainfall does not occur within 10 days after preemergence treatment. Where annual bluegrass is the major weed, use 1 qt. of Princep Liquid per acre (22 ml or 0.75 fl. oz./1,000 sq. ft.). Use 1-2 qt./A Princep Liquid (22-44 ml or 0.75-1.5 fl. oz./1,000 sq. ft.) for control of other weeds. However, do not exceed 1 qt./A of Princep Liquid per treatment on newly sprigged turfgrass or on hybrid bermudagrass.
For control of summer annuals which emerge after the initial application, apply an additional 1 qt./A Princep Liquid at least 30 days after the initial application, but not after June 1. However, do not make more than 2 applications per year.

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49 of 56 people found this answer helpful

Which pre-emergent can you mix with Princep (simazine)?

I have used Dimension with moderate results. If I switch to simazine, how best to augment it (if at all) for a mix of grassy weeds and broadleafs, including Crown Vetch and Henbit?


Both Princep Liquid Herbicide and Dimension 2EW have henbit and many other weeds and grasses on the label for control so either would work well for your needs. We do not recommend mixing the two together as it would not give you any extra control. We contacted several of our experts in the herbicide field and reps at the manufacturers of the products we carry and they all came to use with the same answer. There are no pre-emergent herbicides that will control Crown Vetch. The only way to control it is post-emergent form or by taking the area to bare ground and reseeding with which ever grass you choose. We apologize we could not be of more help for your situation but some weeds like Crown Vetch and also Nutsedge just cannot be controlled prior to germination. Please let us know if you have any other questions.

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35 of 42 people found this answer helpful

See all 71 customer questions

Princep Liquid Herbicide 4 out of 5 stars Rating: 4.1 (11 Reviews / 71 Q&A)

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