What's in this guide
What Is Spurge?
Spurge (Euphorbia spp.) is a warm-season annual broadleaf weed that germinates in late spring and thrives through the hottest months of summer — exactly when your lawn is most stressed and your grass least competitive. It's one of the most prolific seed producers in the broadleaf weed category, which is why once you have spurge, you tend to have a lot of it quickly.
It belongs to the same broadleaf plant family as dandelions and clover, which is good news: the same selective herbicides that eliminate those weeds also work on spurge. The key difference is timing — spurge is a summer annual, so the treatment windows and best-practice approach are different from cool-season weeds like chickweed or dandelions.
Spurge is not a grass or sedge — it's a dicot broadleaf plant. Standard selective broadleaf herbicides (2,4-D, MCPP, Dicamba) work on it. Grassy weed products like quinclorac have no effect. If you're unsure which category your weed falls into, visit our Weed ID Hub before buying anything.
How to Identify Spurge in Your Lawn
Spurge is one of the most distinctive weeds once you know what to look for. It grows in a flat, mat-like pattern radiating outward from a central taproot — often forming dense circular patches that smother surrounding grass. The single most reliable identifier is its milky white latex sap, which oozes immediately when any part of the plant is broken.
Growth habit: Low, mat-forming, spreading outward in a flat pattern from a central stem. Leaves: Small, oval, opposite pairs on the stem. Often has a distinctive dark reddish-purple spot near the centre of the leaf (spotted spurge). Stem: Reddish-purple, hairy. Sap: Break a stem — milky white latex oozes out immediately. This is the definitive test for spurge. Flowers: Tiny, white-pink, barely visible. Season: Summer only — not present in spring or fall.
The milky sap test is foolproof — no other common lawn weed produces white latex sap on breaking. This separates spurge from low-growing lookalikes like chickweed (no sap) or prostrate knotweed (no sap). If you break a stem and white sap appears, it's spurge.
Spurge latex sap can cause skin irritation and eye irritation on contact. Wash hands thoroughly after handling spurge plants. Avoid touching eyes after pulling. The sap is not acutely toxic but prolonged skin contact can cause redness and itching in sensitive individuals. Wear gloves when hand-pulling large infestations.
Spotted Spurge vs Prostrate Spurge
Two species dominate in North American lawns. Both look very similar and respond to the same treatments — the differences are mainly in size and how aggressively they seed.
Both species are treated identically — the ID distinction is mainly useful to confirm you're dealing with spurge rather than another weed. The spotted variety is more common in lawn settings across both countries.
Why Spurge Spreads So Fast
Spurge's spread rate is driven by three factors working together: seed volume, germination speed, and summer timing.
Seed volume: A single spotted spurge plant produces up to 2,500 seeds. A mature plant can seed an entire lawn area within a single summer season if left untreated.
Germination timing: Spurge germinates when soil temperatures reach 60–65°F — typically mid to late spring. This means by the time you see spurge plants in early summer, seeds from those plants are only weeks away from being deposited in the soil for next year.
Summer stress advantage: Spurge grows fastest during the hottest, driest weeks of summer — exactly when cool-season lawn grasses like Kentucky Bluegrass and Fescue go semi-dormant and slow down. Thin, stressed turf gives spurge the gap it needs to establish. Dense, well-watered turf suppresses it.
Because spurge is an annual — it dies each fall and regrows from seed every spring — pre-emergent herbicide applied before soil temperatures hit 60°F blocks the entire generation. One spring pre-emergent treatment can prevent 90%+ of that year's spurge before a single plant appears. See our pre-emergent weed killer guide for timing and product selection.
Pre-Emergent: The Best Spurge Control Strategy
Because spurge is a summer annual — it dies in fall and regrows entirely from seed the following year — pre-emergent herbicide is far more effective than post-emergent treatment. Apply it once in spring before soil temperatures reach 60°F and you prevent the entire season's spurge crop from germinating.
Best Pre-Emergent Products for Spurge
| Active Ingredient | Products | Spurge Control | Apply Timing |
|---|---|---|---|
| Prodiamine 65WDG | Barricade, Prodiamine generic | Excellent — 90%+ | Soil temp 50–55°F (before 60°F) |
| Pendimethalin | Scotts Halts, Pendulum | Excellent — 88%+ | Soil temp 50–55°F |
| Dithiopyr | Dimension | Excellent + early post | Soil temp 50–55°F |
| Isoxaben | Gallery | Very Good — 85%+ | Spring or fall application |
Pre-emergent herbicides prevent all seed germination — including grass seed. If you need to overseed thin areas, do so at least 8–12 weeks before or after pre-emergent application. Applying pre-emergent and overseeding simultaneously is a common mistake that results in failed grass establishment.
Post-Emergent Herbicides & Success Rates
If spurge is already growing, a post-emergent broadleaf herbicide is your tool. Spurge responds well to standard three-way blends early in the season — but success rates drop significantly once plants are large or producing seed capsules. Treat as early in summer as possible for best results.
| Product | Active Ingredient | Early Summer Rate | Late Summer Rate | Region |
|---|---|---|---|---|
| Killex Concentrate | 2,4-D + MCPP + Dicamba | 88% | 62% | 🇨🇦 Canada |
| Weed B Gon Max | 2,4-D + MCPP + Dicamba | 85% | 60% | 🇨🇦🇺🇸 Both |
| Roundup for Lawns | 2,4-D + MCPP + Dicamba + Quinclorac | 82% | 58% | 🇨🇦🇺🇸 Both |
| Trimec Classic | 2,4-D + MCPP + Dicamba | 87% | 61% | 🇺🇸 USA |
| Fiesta (iron-based) | Iron HEDTA | 48% | 30% | 🇨🇦 ON/QC |
Rates measured at 14 days post-application. Early summer = plants under 3 inches. Late summer = mature plants near or at seed stage. Fiesta rates are low on spurge — pre-emergent is the most effective strategy for Ontario and Quebec.
Because Fiesta gives only moderate control on spurge (48% early summer, 30% late summer), Ontario and Quebec homeowners should prioritise the pre-emergent strategy in spring. Prodiamine and pendimethalin-based pre-emergents are permitted for use under the cosmetic pesticide ban regulations. See our full Canada weed control guide for province-specific product details.
How to Apply Post-Emergent — Step by Step
Treat early — don't wait for large plants. Post-emergent herbicides on spurge are most effective when plants are under 3 inches across and have not yet started producing seed capsules. Once you see the tiny seed pods forming, efficacy drops by 20–30%. Early June is the ideal window in most regions.
Don't mow for 3–4 days before applying. Spurge grows low to the ground — you need maximum leaf surface area for absorption. Let it grow out slightly before treating to maximise contact area.
Apply on a warm, calm morning. Spurge is most susceptible when actively growing in warm conditions (above 65°F). Apply in the morning before the hottest part of the day. Avoid applying in extreme heat above 90°F as the herbicide evaporates before absorption.
Mix at the correct rate and add a surfactant. For Killex: 6ml per litre. For Weed B Gon RTU: use as-is. Adding a non-ionic surfactant (0.25%) improves contact on spurge's slightly waxy leaf surface and significantly improves absorption. This optional step can raise efficacy by 8–12%.
Ensure 24–48 hours rain-free after application. Spurge's low, flat growth means runoff is a real risk during rain. Any rainfall before the herbicide is fully absorbed reduces efficacy substantially.
Don't mow for 3–4 days after applying. Allow full translocation from leaf to root. Mowing too soon removes treated foliage before the herbicide has been fully absorbed and moved to the root system.
Plan a pre-emergent for next spring. Post-emergent treats this season's spurge but does nothing for the thousands of seeds already deposited in the soil. Apply a prodiamine or pendimethalin pre-emergent next spring to break the cycle for good. See our pre-emergent guide for timing.
Seasonal Treatment Timing
Apply pre-emergent when soil hits 50–55°F. Blocks spurge germination before it starts. Most effective action you can take — prevents the entire season's crop.
Post-emergent window — treat plants under 3 inches. 82–88% control rate. Do not wait for plants to mature. This is the last effective post-emergent window.
Spurge dies naturally with first frost. Post-emergent now gives poor results. Focus on removing plants before they set more seed. Plan spring pre-emergent.
No active spurge — it's an annual. Seeds are dormant in the soil. Order pre-emergent now and set a calendar reminder for early spring application before soil warms.
Manual Removal
Manual removal is effective for spurge — unlike perennial weeds with deep rhizome networks, spurge has a shallow taproot that can be removed cleanly. The critical requirement: remove it before it seeds.
When Manual Removal Works
- Small infestations caught early in June
- Plants before the seed capsule stage
- Moist soil — taproot comes out cleanly
- Pet-safe households wanting to avoid herbicides
- Spot treatment in areas where herbicide drift is a risk
When Manual Removal Fails
- Large infestations — too time-consuming
- Mature plants already producing seed capsules
- Dry, hard soil — root snaps and regenerates
- If pulled plants are left on the lawn — seeds continue to ripen
Spurge's milky latex sap is a skin irritant. Wear gloves when pulling. More importantly, bag and bin all pulled plants immediately — do not compost or leave on the lawn. Seed capsules on pulled plants continue to ripen and eject seeds even after the plant is detached. Spurge seed capsules can fire seeds up to 15 feet when dry.
Long-Term Prevention
Spurge is an opportunist — it fills bare, thin, and compacted areas of lawn where grass can't compete. Every cultural improvement that thickens your turf directly reduces spurge pressure the following season.
Overseed thin patches immediately after treating spurge — the bare areas left behind are exactly where spurge establishes the following year. See our overseeding guide for timing and technique.
Raise mowing height to 3–3.5 inches through summer. Taller grass shades the soil surface, reducing soil temperature and reducing the germination conditions spurge needs. Scalped lawns give spurge a massive competitive advantage.
Water deeply but infrequently — spurge thrives in hot, dry, shallow-rooted turf. Deep watering (1 inch per week in 2–3 sessions) encourages grass roots to grow deep, creating a denser, more competitive turf canopy.
Apply pre-emergent every spring as a maintenance dose. Even after gaining control of spurge, an annual spring pre-emergent application at a maintenance rate (half the full rate) prevents re-establishment from seeds blowing in from neighbouring areas.
Spurge is fully controllable because it's an annual — apply pre-emergent prodiamine in spring before soil hits 60°F and you prevent 90%+ of that season's crop. For existing plants, treat early in summer with a standard three-way broadleaf herbicide (82–88% rate). Thick turf and overseeding bare patches are the most effective long-term prevention.