The flat green mat that shows up between pavers and in DG every summer. How to tell it apart, when it sprouts, and how to stop the next round.
Get a Free Yard EstimateSpotted spurge is a low, mat-forming summer weed with small paired leaves, often marked with a red spot, and milky sap that irritates skin. It can set seed as soon as five weeks after it sprouts, so the most effective control is a pre-emergent applied before the soil at 1 inch deep warms past 55 to 60°F, plus pulling any plants that get through while they are young.
Spurge loves the same conditions a High Desert rock or DG yard gives it: bare ground, heat and a little water from drip or a sprinkler. Every fact below is from UC IPM’s Pest Note on spotted spurge (UC IPM) unless another source is linked.
This page is part of our High Desert weeds guide.
Three low-growing weeds get mixed up in High Desert yards. Here is how UC IPM describes each:
| Weed | Leaves | Flowers | Other clues |
|---|---|---|---|
| Spotted spurge | Dark green, in pairs, 1/8 to 1/2 inch long, often with a red spot halfway down the center vein (UC IPM) | Tiny and pinkish | Milky sap when you break a stem. Summer weed. |
| Puncturevine | Divided into four to eight pairs of leaflets; seedlings covered in soft hairs (UC IPM) | Yellow, five petals, up to 1/2 inch | Spiny burs follow the flowers. Summer weed. |
| Redstem filaree | Low rosette, leaves fully divided into leaflets, stems often reddish (UC IPM) | Pink to lavender, five petals | Corkscrew seeds. Winter weed, not summer. |
The fastest field test: snap a stem. If white milky sap comes out, you are looking at spurge.
Prostrate spurge is a close relative that looks very similar. UC’s pest note is written for spotted spurge, and we did not confirm that every number on this page applies the same way to prostrate spurge, so treat the timing below as a close guide for both, not a guarantee.
UC IPM says the milky sap is a skin irritant and recommends wearing gloves when you pull it (UC IPM). Pulling spurge bare-handed in a July rock bed is a good way to find out. Gloves, long sleeves, and wash up after.
UC IPM says spotted spurge germinates best at 75 to 85°F, and can germinate at temperatures as low as 60°F (UC IPM). That is why the pre-emergent trigger is lower: UC says to apply before the soil temperature exceeds 55 to 60°F at a depth of 1 inch.
How that plays out in the Victor Valley is our estimate from Victorville’s NOAA 1991-2020 normals, taking the average of the normal daily high and low air temperature (NOAA):
| Month | Mean air temp (our math) | What it means for spurge |
|---|---|---|
| March | 53.4°F | Getting close to the pre-emergent trigger. Have it down by mid-March. |
| April | 58.6°F | In the 55 to 60°F range. Too late to start pre-emergent in most yards. |
| June | 74.7°F | Near the 75 to 85°F best-germination range. |
| July and August | 80.9°F and 80.2°F | Right in the best range. |
| September | 74.4°F | Still close. New plants keep coming. |
Air temperature is not soil temperature, so check with a soil thermometer at 1 inch. The full pre-emergent timing and how we derived it is on our weeds in rock and gravel page.
Fast. UC IPM says spotted spurge can produce seed as soon as 5 weeks after germination, and one plant can make several thousand seeds (UC IPM). With the High Desert’s long warm season, that leaves room for more than one generation in a single summer if nobody pulls them.
A practical schedule: walk your rock and DG beds every two to three weeks from late spring through September and pull every spurge you find. That interval is our suggestion based on the five-week seed window, not a UC rule. Get the whole plant, root included.
It helps a lot, if it is thick enough. UC IPM recommends mulch at least 2 inches thick, or a 3- to 4-inch layer for large bark (UC IPM). The reason it works: spurge seeds buried deeper than 1/2 inch do not germinate well.
Rock works on the same idea, with one catch. UC IPM notes that rock mulch is difficult to keep weed-free (UC IPM). Seed that lands on top of the rock and settles into dust between the stones is not buried at all. That is why rock beds in the High Desert still get spurge, and why pre-emergent plus a regular walk-through still matters. The fabric and rock depth details are on the rock and gravel page.
Check the joints around pavers and the edges of artificial turf too, anywhere a strip of soil is open to the sun.
Spotted spurge has small dark green leaves in pairs, 1/8 to 1/2 inch long, often with a red spot on the center vein, and tiny pinkish flowers. Break a stem and it bleeds milky sap. Puncturevine has leaves split into many paired leaflets and yellow flowers, and redstem filaree grows as a rosette with pink flowers in winter.
UC IPM says spotted spurge germinates best at 75 to 85 degrees and can germinate as low as 60 degrees. It says to apply pre-emergent before the soil at 1 inch deep goes above 55 to 60 degrees. For the Victor Valley floor we estimate that means late February to mid-March.
UC IPM says spotted spurge sap is a skin irritant and recommends wearing gloves when you handle it. Long sleeves and washing up afterward are good practice too.
UC IPM says spotted spurge can make seed as soon as 5 weeks after it sprouts, and one plant can produce several thousand seeds. Pulling every two to three weeks through the warm season keeps plants from reaching that point.
Mulch at least 2 inches thick helps because spurge seed buried deeper than half an inch does not germinate well, according to UC IPM. Rock works the same way for seed below it, but seed that blows in on top of the rock can still sprout, so a pre-emergent and regular pulling are still needed.
We checked every number on this page against the public sources below. If a rule or date changes, the agency page is the final word.
Monarch builds rockscapes and DG yards across the High Desert with fabric under the rock and drip that waters the plants, not the bare ground in between. We do not sell weed spraying. Get a free estimate and a straight answer on what your yard needs.
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