The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Prodiamine (CAS 29091-21-2)
- Chemical class
- Dinitroaniline preemergence herbicide.[3][1]
- Mode of action
- WSSA Group 3: Microtubule assembly inhibitors (dinitroanilines)[3]
- Signal word
- Prodiamine 0.42% Plus (Greenskeeper's Secret Prodiamine 0.42% Crabgrass Preventer): Caution[2]
How it works
Prodiamine interferes with plant root and shoot development, preventing weed seedlings from growing.[1]
The label says it works by inhibiting weed seed germination and root development, so every application must go down before the target weeds germinate, and the length of control depends on the rate applied.[2]
Planning around seeding
Because it stops roots, it also injures desirable grass seedlings if applied before their secondary roots reach the second inch of soil; disturbing the treated layer by disking or similar work weakens the barrier.[2]
Where it is used
For best control it must be watered in by at least half an inch of rain or irrigation, or shallow incorporation, before weed seeds germinate and within 14 days of application.[2]
Do not apply to newly overseeded turf for 60 days or until after the second mowing, whichever is longer, and do not apply to newly laid sod until the following year.[2]
Avoid applying to lawns stressed by drought, low fertility or pests, and never on putting greens or where dichondra, colonial or velvet bentgrass or annual bluegrass are wanted.[2]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Prodiamine 0.42% Plus (Greenskeeper's Secret Prodiamine 0.42% Crabgrass Preventer)[2] | Control Solutions, Inc. | 53883-297 | 0.42% | granular (on fertilizer) | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Prodiamine 0.42% Plus (Greenskeeper's Secret Prodiamine 0.42% Crabgrass Preventer) | Established lawns: yearly maximum by grass type | Crabgrass, goosegrass, foxtail, chickweed, henbit, spurge and other weeds from seed | 3.6–8.2 lb per 1,000 sq ft per year[2] Yearly maximum of product per 1,000 sq ft: 3.6 lb for creeping bentgrass; 4.1 for creeping red fescue and buffalograss; 5.5 for Kentucky bluegrass and perennial ryegrass; 8.2 for bermuda, bahia, centipede, St. Augustine, tall fescue and zoysia. Can be split into sequential applications. |
How to apply it, step by step
1. Protective gear
- Wear protective eyewear: the granules cause moderate eye irritation. Keep them off your clothing and wash with soap and water after handling.[2]
2. Before you spray
- It is a preemergence herbicide for established lawns and landscape ornamentals: it stops weed seeds from germinating and rooting, so it does nothing to weeds that are already up. Every application must go down before the weed seeds germinate.[2]
- It can thin annual bluegrass and newly seeded grass: don't apply it to overseeded turf within 60 days of seeding or before the second mowing (whichever is later), or to new sod until the following year.[2]
- Apply it in calm weather with no heavy rain forecast for 24 hours, keep it off water, and sweep granules off pavement back onto the lawn.[2]
3. Mixing
- No mixing: the granules go on with a calibrated spreader at the setting on the label for your spreader.[2]
4. Applying
- Spread it evenly. The yearly maximum depends on the grass species, from 3.6 lb of product per 1,000 sq ft (creeping bentgrass) up to 8.2 lb, the cap for any species.[2]
- For goosegrass and other heavy pressure, the label allows a split program: 3.6 to 5.5 lb per 1,000 sq ft, then a second application 60 to 90 days later, without going over the species' yearly maximum.[2]
- Higher rates give longer control but delay reseeding: the label's table shows how many months to wait before overseeding at each rate.[2]
5. After you spray
- It needs at least ½ inch of rain or irrigation (or shallow raking-in of 1 to 2 inches) within 14 days and before weed seeds germinate to work.[2]
- Don't graze or feed livestock forage cut from treated areas, and don't cut treated sod for 120 days.[2]
First aid
- In the eyes, rinse slowly and gently for 15 to 20 minutes, removing contact lenses after 5 minutes; on skin or clothing, take off contaminated clothing and rinse for 15 to 20 minutes.[2]
- If swallowed, call a poison control center or doctor right away, have the person sip water if they can swallow, and don't induce vomiting unless told to; if inhaled, move the person to fresh air. The label lists SafetyCall International, 1-866-897-8050.[2]
Storage, spills and disposal
Safety and environmental hazards
People
The label signal word is CAUTION: it causes moderate eye irritation, so wear protective eyewear and wash after handling.[2]
Pets
The label's hazard statement for people and domestic animals is moderate eye irritation; it lists no separate pet re-entry period.[2]
Bees and pollinators
The label carries no bee hazard statement.[2]
Fish and water
The label says prodiamine has low solubility in water and is not toxic to fish at its solubility limit but may be at higher concentrations; it is toxic to plants, so keep drift and runoff away from water and desirable plants.[2]
Common questions
- How much prodiamine can I put on my lawn per year?
- It depends on the grass: this 0.42% granular allows 5.5 lb per 1,000 sq ft per year on Kentucky bluegrass and perennial ryegrass, and 8.2 lb on bermuda, St. Augustine, zoysia and tall fescue.[2]
- Does prodiamine need to be watered in?
- Yes. The label says it works best when activated by at least half an inch of rain or irrigation within 14 days and before weeds germinate.[2]
- Can I seed after applying prodiamine?
- Plan carefully. It can injure grass seedlings, and the label bars applying it to overseeded turf for 60 days or until after the second mowing.[2]
- Will prodiamine kill crabgrass that is already growing?
- No. The label says it will not control established weeds.[2]
Sources
- University of California Statewide IPM Program, “Home and Landscape Pesticide Active Ingredients Database: prodiamine.” ipm.ucanr.edu/home-and-landscape/pesticide-active-ingredients-database/active-ingredient-details/?uaiKey=51 (accessed 2026-10-06)
- U.S. EPA Pesticide Product Label System, “Prodiamine 0.42% Plus label, EPA Reg. No. 53883-297 (EPA-stamped, Apr. 3, 2025).” www3.epa.gov/pesticides/chem_search/ppls/053883-00297-20250403.pdf (accessed 2026-10-06)
- Weed Science Society of America, “Summary of Herbicide Mechanism of Action According to the Weed Science Society of America.” wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf (accessed 2026-10-06)