Customers ask us four questions about Killex: how long before it can rain, when can I water, can I mow, and how much do I mix. The answers are on the label that Health Canada registered for Ortho Killex Lawn Weed Control Concentrate (Registration No. 27801). This article quotes that label; it is not a substitute for reading the one on the bottle you buy. For the full list of weeds the label names, see What weeds does Killex control? The full label list.
How long does Killex need before rain?
The label puts it in two sentences: "DO NOT water within 24 hours after application. Do not apply when rain is expected." So plan for a dry 24 hours after spraying, and if the forecast shows rain, wait. The label also says to "avoid application during long, dry periods" and to "avoid application of this product when winds are gusty" — drought-stressed weeds are not growing, and wind carries spray where it should not go.
Can I spray Killex on wet grass?
The Killex Concentrate label (PCP Reg. No. 27801) does not mention dew or wet grass either way; we searched its text for both. What it does set is the water rule around the application: "DO NOT water within 24 hours after application. Do not apply when rain is expected." It also says "This product is only effective when applied to the leaves of actively growing weeds." The label gives no instruction for dew-wet or freshly watered grass, so we will not invent one: follow the lines it does give, and check the label on your own container before you spray.
When does Killex actually work?
"This product is only effective when applied to the leaves of actively growing weeds." That is the whole timing rule: green, growing weeds. Killex is a post-emergent — the label is explicit that "this product will not prevent new weeds," which is the job of a pre-emergent such as Scotts Turf Builder Weed & Feed, a corn-gluten product that Scotts says stops dandelion and crabgrass seed from germinating but "established weeds at the time of the application, will not be controlled."
Can I use Killex on a new lawn, and what about mowing?
"Do not apply to newly seeded lawns until after 3rd mowing." That is the only mowing instruction on the label — it protects seedlings, which have too little leaf to tolerate a broadleaf herbicide. The label does not set a mowing interval for established lawns; the practical reading of "applied to the leaves of actively growing weeds" is that you want weed leaf area present when you spray, so spraying right after a close mow gives the product less to land on.
What is the mix rate for Killex concentrate?
"Mix 6 mL of concentrate in 1 litre of water to treat 5 square metres (50 square feet)." The label writes the rate per litre; scaled to a gallon of water, the same rate works out to about 23 mL per US gallon (3.785 L) or about 27 mL per imperial gallon (4.546 L). For a hose-end sprayer, the label says: "Set the dial on the Dial 'N Spray applicator to 6 and follow label directions." We carry the Scotts Dial N Spray hose-end sprayer alongside the Killex Concentrate 1 L. If you would rather not mix, the Ready-To-Spray 1 L connects to the hose, and the Ready-To-Use 709 mL and Ready-To-Use 4 L with wand are pre-mixed for spot treatment.
How many times a season?
"DO NOT apply more than two broadcast applications per season." The label adds that "for good turf/lawn management, normally two applications per year per treatment site are adequate." The label rule is the count, not the calendar.
Keeping people, pets and the garden safe
Three label lines cover it: "Do not allow people (other than the applicator) or pets on the treatment area during application." "Do not enter treated areas until spray has thoroughly dried." And for the flower bed next to the lawn: "DO NOT directly spray or allow the spray to drift onto ornamental plants and trees, fruits, vegetables or exposed roots of trees and ornamentals." Killex is a selective broadleaf herbicide — its three actives are 2,4-D (95 g a.e./L), mecoprop-P (52.52 g a.e./L) and dicamba (9 g a.e./L) — and the label treats broadleaf garden plants as at risk from drift.
Which product for which job?
Our Killex vs Roundup guide covers the difference between a selective lawn herbicide and a non-selective one, the four Killex formats, and whether Killex is legal where you live. All four Killex products are listed at Pipestone Farm Supply in Millet, Alberta — see the weed and moss control category and the Ortho brand page.
Sources: Health Canada Pesticide Label Search, Ortho Killex Lawn Weed Control Concentrate, Registration No. 27801 (pr-rp.hc-sc.gc.ca); Scotts Canada product page for Turf Builder Weed and Feed (scottsmiraclegro.com/en-ca). Always read and follow the label on the product you buy.