Quick take:
- Treflan 5G is a granular pre-emergent herbicide with 5 percent trifluralin that blocks weed seed germination in ornamental beds, nursery stock, and ground covers.
- It must go down before weeds sprout and be watered in to form an effective soil barrier.
- One application can hold back annual grasses and broadleaf weeds for up to three months.
Gardeners and landscape crews searching for a reliable way to stop crabgrass, pigweed, and other annual weeds before they appear often land on Treflan Pre Emergent from ProSolutions as a practical option for ornamental beds and nursery sites. Unlike post-emergent sprays that target weeds already growing, this granular product is designed to be applied before germination begins, creating a chemical barrier in the top layer of soil. Understanding how that barrier forms, and the narrow window when it actually works, makes the difference between a clean bed and a wasted bag of product.
What Treflan Pre-Emergent Actually Does in the Soil
Trifluralin, the active ingredient in Treflan 5G, does not kill mature plants or existing weeds. Instead, it interferes with cell division in germinating seeds, stopping root formation before a seedling can establish itself. The product label confirms this product is a preemergence herbicide for control of certain annual grasses and broadleaf weeds in container grown ornamentals, landscape ornamentals, nursery stock, ground covers, established flowers, ornamental bulbs, and non-bearing fruit and nut trees.
A few practical points about how it behaves once applied:
- It forms a barrier when activated with water, which keeps weed seeds beneath the surface from sprouting.
- One application can provide control for up to three months, depending on conditions.
- It does not control weeds that have already emerged, so beds should be cleared of existing growth first.
Because trifluralin binds tightly to soil particles and has limited mobility, timing and placement matter more than volume. The compound’s mechanism of action involves disrupting microtubule formation, which prevents the mitotic spindle from assembling correctly during cell division, according to a peer-reviewed review on trifluralin’s modes of action published by IntechOpen.
Application Rates and Timing Guidelines
Treflan 5G is labeled for a specific rate range, and going outside that range either wastes product or risks injuring desirable plants. The standard labeled rate is 1.8 pounds per 1,000 square feet, or roughly 80 pounds per acre. A 40-pound bag typically covers up to 22,000 square feet, which makes it practical for mid-sized ornamental beds, nursery rows, and landscaped commercial properties.
|
Application Detail |
Specification |
|
Active ingredient |
Trifluralin 5.0 percent |
|
Standard rate |
1.8 lbs per 1,000 sq ft (80 lbs/acre) |
|
Coverage per 40 lb bag |
Up to 22,000 sq ft |
|
Duration of control |
Up to 3 months per application |
|
Activation requirement |
Water in soon after application |
Apply the granules to a weed-free soil surface, then water them in to activate the barrier. For ornamental bulbs specifically, the product should go down two to four weeks after planting but before weeds emerge, and a second application in late winter or early spring is appropriate for fall-planted bulbs. Skipping the watering step is one of the most common reasons a pre-emergent underperforms, since the granules need moisture to move into the top layer of soil where germinating seeds are most vulnerable.
Safety Considerations Before You Spread It
Trifluralin is not labeled for residential lawn turfgrass, so it should be reserved for ornamental beds, nursery stock, ground covers, and non-cropland areas as specified on the product label. The EPA classifies trifluralin as slightly toxic for acute dermal and inhalation exposure, which means basic precautions like gloves and avoiding drift onto desirable plants are worth following, according to the EPA’s trifluralin reregistration fact sheet. Applicators should also avoid treating areas near open water or where runoff could reach aquatic habitats, since the product can affect non-target organisms adjacent to the treated site.
Three habits reduce risk and improve results:
1. Read the full label before each use, since site restrictions vary by plant type.
2. Clear existing weeds mechanically before applying, since the product will not kill what is already growing.
3. Store unused granules in their original container in a cool, dry, locked space away from children and pets.
Frequently Asked Questions
Does Treflan kill weeds that have already sprouted? No. It only prevents new seeds from germinating and will not affect weeds that are already visible in the bed.
How soon after applying does it need water? The granules should be watered in shortly after spreading so the active ingredient moves into the soil surface and forms an effective barrier.
Can it be used on home lawns? Trifluralin 5G formulations are generally labeled for ornamental beds, nursery stock, and non-cropland areas rather than residential turfgrass, so always check the specific product label for approved sites.
How long does one application last? Under typical conditions, a single application can suppress annual grasses and broadleaf weeds for up to three months before a follow-up may be needed.
Finding the Right Pre-Emergent Supplier
ProSolutions supplies professional-grade turf, ornamental, and pest control products, connecting landscape crews and home growers with trusted brand-name and generic solutions for everyday field challenges. Anyone comparing pre-emergent options for an upcoming planting season can review current product specifications, labels, and pricing before placing an order. For questions about coverage area or site-specific suitability, reach out directly or look up ProSolutions on Google Maps to see hours, contact details, and additional product information before making a purchase decision.
