Every fall we get the same two questions at the counter in Millet: "Do I want Killex or Roundup?" and "What's the mix rate on the Killex concentrate?" The first one has a clear answer. The second one is on the label, and we'll tell you where to look and why we won't guess it for you.
The one-sentence difference
Killex is selective. Roundup is not. Ortho Killex is a lawn weed killer that targets broadleaf weeds and, in the manufacturer's words, "does not harm the lawn" when used as directed. Roundup's core products are labelled Non-Selective Herbicide — they kill grass as readily as weeds. Spray Roundup on a dandelion in the middle of the lawn and you will get a dead dandelion in the middle of a dead patch.
So: weeds in the lawn → Killex (or Scotts Weed B Gon, below). Weeds where you want nothing growing at all — gravel driveways, fence lines, under decks, cracks in paving, or a bed you are clearing before replanting → Roundup.
What Killex actually is
The Ortho Killex Lawn Weed Control Concentrate label lists three active ingredients: 2,4-D (as the dimethylamine salt) 9%, mecoprop-P 5% and dicamba (dimethylamine salt) 1%, and it is registered under the Pest Control Products Act as PCP number 27801. Ortho says it "controls over 50 varieties of broadleaf weeds in the lawn"; the retail listing names dandelion, plantain, chickweed, clover, bedstraw, black medick, heal-all, ground ivy (creeping Charlie), knotweed, ragweed, shepherd's-purse, poison ivy, devil's paintbrush, buttercup and English daisy. The manufacturer's timing advice is short: "Apply when weeds are young and actively growing." For a prairie lawn that usually means two windows — late spring, and early fall while the grass and weeds are still growing before freeze-up.
Ortho also notes that Killex is "not available in all provinces." It is sold in Alberta, which is why you will find it on our shelf; some other provinces and a few municipalities restrict cosmetic 2,4-D use, so if you are buying for a lawn elsewhere, check locally first.
The four Killex formats we carry, and who each one suits
Ortho Killex Lawn Weed Control Concentrate 1 L — the economical choice for a whole lawn or an acreage yard. Ortho rates the 1 L bottle at 800 m² (about 8,800 sq ft) of coverage. You mix it with water in a hand-held or backpack sprayer, or run it through a Scotts Dial 'N Spray hose-end applicator, which dilutes as it goes. The bottle has a built-in measuring cap. It works as a broadcast treatment over the whole lawn or as a spot treatment.
Ortho Killex Ready-To-Spray Lawn Weed Control 1 L — the same job with no measuring: it attaches to a garden hose and mixes itself. Best for a typical town lot where you want to treat the whole lawn in one pass.
Ortho Killex Ready-To-Use Lawn Weed Control 709 mL — a trigger spray for spot-treating a handful of weeds. No mixing, no sprayer to clean.
Ortho Killex Ready-To-Use with Wand Applicator 4 L — pre-mixed like the trigger bottle but in a jug with a wand, so you can spot-treat a lot of weeds without bending over or refilling.
"What's the mix rate for Killex concentrate?"
It is printed on the back label of the bottle, in a table by application method, and it is the only number you should use. Rates on pesticide labels are legally binding directions in Canada, they are specific to the exact registration number on your bottle, and manufacturers do change them between label versions. Here is what to look for on the Killex Concentrate label when you have it in hand:
- the millilitres of concentrate per litre of water for a hand or backpack sprayer, and the area that mix covers;
- the setting to use on a Dial 'N Spray hose-end sprayer if that is how you apply it;
- the maximum number of applications per season and the minimum interval between them;
- the re-entry direction (when people and pets can go back on the lawn), and any guidance on rain, mowing and watering around the application;
- the drift cautions — 2,4-D and dicamba labels warn against letting spray or mist reach flowers, vegetables, shrubs and trees, so spray on a still morning.
If your bottle's label is worn or missing, the Ortho Canada product page for the concentrate is the manufacturer's reference, and the store can look up the current label for you.
Where Roundup fits
Our Roundup range is all in the weed and moss control category, and the labels fall into three groups:
- Concentrates for mixing — Roundup Concentrate Non-Selective Herbicide 1 L and 500 mL, Roundup Super Concentrate 1 L and Roundup Advanced Concentrate 1 L. These are for large areas: fence lines, corrals you are clearing, gravel yards, driveways.
- Ready-to-use jugs and sprays — Roundup Ready-To-Use with Wand Applicator 4 L (and the 4 L refill), Roundup Advanced Ready-To-Use with Pump N Go 5 L, and the FastAct Foam 1 L and 2 L sprays, which come out as a foam.
- Roundup Ready-To-Use Tough Brush & Poison Ivy Control with Wand Applicator 4 L — a separate formulation labelled for woody brush and poison ivy rather than lawn weeds. If poison ivy is coming up in the lawn, note that it is also on the Killex weed list; if it is in a fence line or bush edge where you do not care about the grass, this is the Roundup to reach for.
As with Killex, the label on the jug carries the rate, the timing and the re-entry direction, and every one of these products is regulated as a pesticide by Health Canada. Read the label, keep people and pets off treated areas as it directs, and do not spray near open water.
Weed B Gon: the third option
If you would rather not use 2,4-D on your lawn, Scotts Weed B Gon MAX is the other selective lawn weed control we stock, in concentrate 1 L, concentrate 500 mL, ready-to-spray 1 L and ready-to-use 1 L. It is a different chemistry with its own label and its own weed list, so read it the same way. For moss rather than weeds, Scotts also makes Moss B Gon MAX 3-in-1.
Quick decision list
- Dandelions, clover, plantain or creeping Charlie in the lawn → Killex (concentrate for big lawns, ready-to-spray for a town lot, ready-to-use for a few spots).
- Weeds in gravel, paving, fence lines or a bed you are clearing → Roundup.
- Poison ivy in the lawn → Killex lists it; in brush or fence lines → Roundup Tough Brush & Poison Ivy.
- You want to avoid 2,4-D on the lawn → Scotts Weed B Gon MAX.
- Fall timing on the prairies → while weeds are still green and actively growing, before the first hard freeze.
All of these are on the shelf at Pipestone Farm Supply in Millet and ship across Canada from our Ortho, Roundup and Scotts brand pages.
Sources: Ortho Canada product pages for Killex Lawn Weed Control Concentrate and Ready-To-Use (scottsmiraclegro.com/en-ca); Ortho Killex Lawn Weed Control Concentrate Safety Data Sheet (active ingredients, PCP registration number 27801, hazard statements); product names as registered on the Roundup and Scotts labels. This article describes what the labels say; it is not a substitute for reading the label on the product you buy.