Garden Guy Mixing Guide
How to Mix Celsius® WG — the Right Amount, Every Time
The question we get more than any other about Celsius: “How much do I put in my sprayer?” Here’s the straight answer, taken from the product label, with Todd’s notes from more than 30 years on Houston lawns.
The short answer
½ to 1 level teaspoon per gallon of water, depending on the weed. One gallon covers up to 1,000 sq ft.
Using the little single-dose packet? One packet goes in 2 gallons (high rate) up to 4 gallons (low rate).
Read this first: The current Celsius WG label states it is intended for commercial application by licensed applicators. This page is a label reference, not a substitute for it. Always read and follow the full label on your container.
Mixing Calculator
Tap your answers. We’ll do the math.
Pick how you’re measuring, which weed you’re after, and the size of your sprayer. Your mix shows up in the green box at the bottom.
Your mix
Add 1 level tsp of Celsius WG to 1 gallon of water.
Treats up to 1,000 sq ft.
Todd’s tip: Use level measuring spoons and keep a set just for lawn products. Never put them back in the kitchen drawer.
Free printable
Want this chart on paper, next to your sprayer?
Get the Celsius WG Mixing Card: every rate, every sprayer size, and the mixing order, all on one printable card. Enter your email below. ↓
Rates by Weed
There’s no single “default” rate
The label lists a rate for each weed. Find your weed on the label, then use the matching amount below. Amounts are for 1 gallon of finished spray, which covers up to 1,000 sq ft.
½ tsp per gallon · or 1 packet in 4 gallons
Easy-to-control labeled weeds; lighter pressure.
¾ tsp per gallon · or 1 packet in 2¾ gallons
Many labeled broadleaf weeds and sedges.
1 tsp per gallon · or 1 packet in 2 gallons
Tough weeds: doveweed, Virginia buttonweed, annual lespedeza, prostrate spurge, large crabgrass.
Using a 32 oz bottle? Use one-quarter of the gallon amount. But never step up to a higher rate just because it’s easier to measure.
Using a packet? Each 0.226 oz packet is pre-measured. Pour in the whole packet and match the water to your rate. Don’t try to split one.
Surfactant
Surfactant is optional, not automatic
A non-ionic surfactant helps the spray stick to the weed. The label says to add one only when weed pressure is high and thorough coverage is critical.
Liquid Harvest’s own label lists 1.5 tsp per gallon for general use. When you pair it with Celsius, follow the Celsius rate.
Improves coverage when it’s warranted. Spray to wet, not dripping. Stay below 90°F.
Fine when coverage matters and your equipment is calibrated. Stay below 90°F.
Todd’s call: he leaves surfactant out when spot-treating St. Augustine to stay on the safe side. Celsius still works here without it.
Label: no adjuvant above 90°F or on stressed turf. That limit is on the surfactant. Celsius itself may still be applied without one, though St. Augustine spot treatments above 90°F may slow the grass down for a while.
Label = straight from the product label. Todd’s call = Todd’s cautious field preference, not a label rule.
Don’t memorize it
Surfactant rules, sprayer chart and shop links on one card
Grab the free Celsius WG Mixing Card and keep it in the garage. We’ll email it right over. ↓
Mixing Order
Mix in this order, every time
Celsius is a dry granule. Order matters so it dissolves fully and doesn’t clump in the bottom of your sprayer.
- 1Add one-quarter to one-half of your water to the sprayer first.
- 2Add the Celsius WG. Swirl until the granules fully disperse before adding more water.
- 3Fill to your target amount with the rest of the water.
- 4Using a surfactant? Add it last while mixing, and keep shaking the sprayer as you go.
- 5Mix only what you’ll use that day. Don’t store leftover mix.
Spraying tips: Spray weeds until they’re wet, not dripping. Apply only to established, actively growing grass that isn’t stressed. Stay off the lawn (people and pets) until the spray is completely dry.
Label Must-Knows
Read these before every application
Never use it on
Bahiagrass, seashore paspalum, or cool-season grass (tall or fine fescue, Kentucky bluegrass, ryegrass).
Labeled lawns
Warm-season grass listed on the label, such as St. Augustine, Bermuda, Zoysia and centipede. It must be established, actively growing, and not stressed.
Yearly limit
No more than 0.17 oz of product per 1,000 sq ft per year. One high-rate plus one low-rate application reaches it.
Watch the heat
No surfactant above 90°F or on heat- or drought-stressed grass.
Protect yourself
Long sleeves, long pants, shoes and socks, and chemical-resistant gloves.
Protect your beds
Avoid ornamental plants, spray drift, and the roots of newly planted ornamentals. Keep people and pets off until the spray is completely dry.
It is a violation of federal law to use any pesticide in a manner inconsistent with its labeling.
Free printable
Get the free Celsius WG Mixing Card
A printable 3-page card: tape the mixing chart inside the shed door, next to your sprayer.
- Rates by weed in spoons, grams and packets
- A sprayer-size chart: 32 oz, 1, 2 and 4 gallons
- Surfactant rules by grass type, including Todd’s St. Augustine call
- Mixing order, label must-knows, and where to buy
Enter your email below and we’ll send it right over. ↓
What Todd uses
Get everything in one stop
Shop the store you like. Walmart’s Tough Lawn Weed Kit has Celsius packets, a sprayer, a scale, surfactant, gloves and marker flags. Our Amazon collection keeps it simple: Celsius WG plus Liquid Harvest surfactant.
As an Amazon Associate, Garden Guy earns from qualifying purchases. We may also earn a commission from Walmart purchases made through our links, at no extra cost to you.
Questions We Hear a Lot
Celsius WG FAQ
How much Celsius WG do I mix per gallon?
½ level teaspoon (low rate), ¾ teaspoon (middle) or 1 teaspoon (high) per gallon of water, depending on the rate the label lists for your weed. One gallon covers up to 1,000 sq ft.
How many gallons does one Celsius packet make?
Each 0.226 oz single-dose packet goes in 2 gallons at the high rate (2,000 sq ft), 2¾ gallons at the middle rate, or 4 gallons at the low rate (4,000 sq ft). Use the whole packet. Don’t try to split it.
Is Celsius safe on St. Augustine grass?
St. Augustine is on the label, along with Bermuda, Zoysia and centipede. The grass must be established, actively growing and not stressed. Never use Celsius on bahiagrass, seashore paspalum or cool-season grasses.
Do I need a surfactant with Celsius?
Not always. The label calls for a non-ionic surfactant only when weed pressure is high and coverage is critical, at 0.25% (about 1.9 tsp per gallon). Never add one above 90°F or on stressed grass. Todd skips it for St. Augustine spot spraying.
Can I spray Celsius when it’s hot out?
Celsius can still be applied in heat, but without surfactant above 90°F. On St. Augustine, spot treatments above 90°F may slow the grass down for a while. Early morning on a cooler day is your friend.
How fast does Celsius work?
Weeds stop growing quickly, but it’s not instant. Expect yellowing, then browning, with control in about one to four weeks. It works best when temperatures are above 65°F.
How many times a year can I use it?
The yearly limit is 0.17 oz of product per 1,000 sq ft. One high-rate plus one low-rate application reaches it, so plan your second pass carefully.
Can I mix a batch and save it?
No. Mix only what you’ll use that day.
Is Celsius Todd’s pick for nutgrass?
For nutgrass, Todd sticks with one method: Sedgehammer plus a surfactant. Here’s the full plan: How to kill nutgrass in Houston lawns.
Still not sure which rate fits your weed?
Send us a photo and your question, or book a call with Todd. He’s an Aggie horticulturist who has been fixing Sugar Land, Missouri City and Greater Houston lawns since 1991.
Can’t tell what the weed is? Start with our Texas Lawn Weed ID Guide. More lawn help lives in our Houston Lawn Care hub.
— Todd & Sabrina Farber, Garden Guy
For information only. Rates come from the current Celsius® WG label (Environmental Science U.S., LLC / Envu, EPA Reg. No. 101563-141; older packaging may show 432-1507) and the Liquid Harvest non-ionic surfactant label. Labels change, so always read and follow the complete label on your container before mixing or applying any pesticide. The current Celsius WG label states it is intended for commercial application by licensed applicators; if you are not licensed, consult one before use. Celsius is a registered trademark of Environmental Science U.S., LLC. Garden Guy Inc. is not affiliated with either manufacturer and assumes no liability for misuse or improper application.