One of the most pervasive weeds of summer – in lawns as well as garden beds – is spotted spurge. This little ground-hugger is a tenacious mat-former that can quickly spread up to three feet across, choking out desirable grass in the process.
Although spotted spurge and its nearly identical cousin, prostrate spurge, are summer annual weeds that die with frost, they’re heavy seeders that capitalize each year on bare ground and thin lawns.
How to recognize spurge
Both spotted and prostrate spurges grow outward very low to the ground (under mowing height), and they have small green leaves that are opposite one another on wiry stems. Two distinctive traits are the maroon splotches in the center of most leaves and the white, milky sap that comes out when a stem is broken.
Spotted spurge is native to eastern North America and is good at growing in some of the poorest sites, including compacted lawns, hot roadside beds, and even sidewalk cracks. It prefers full sun.
Seeds sprout in late spring to early summer when the soil warms and air temperatures consistently top 75 degrees. Plants become particularly noticeable by mid to late summer.
Plants then produce tiny, pinkish-white flowers that lead to fruit capsules that house seeds. When the seeds mature, each plant is capable of dropping thousands of new seeds, most of which lay dormant until sprouting the following year. The seeds are also sticky and easily move around on mower wheels, shoes, and the fur of rodents.
Seeds that work their way into the soil can stay viable but dormant for years.
How to control spurge in the lawn
In lawns, the best way to stop spurge – and other lawn weeds, for that matter – is to encourage a dense lawn. That way there’s no room for weeds to elbow their way in.
Regular fertilizing, mowing high, aerating compacted soil, top-dressing with compost, and especially overseeding thin lawns with additional grass seed each fall are among the ways to maintain a dense, weed-rejecting lawn.
Read more on overseeding
The second line of spurge defense is to apply a granular product each spring that prevents spurge from sprouting.
Numerous liquid herbicides also can be used to spot-spray spurges if you just have a few patches here and there. Just be sure to pick one that’s labeled for spurge control and for use in lawns as opposed to a spray that kills grass as well as weeds.
How to control spurge in the garden
In garden beds, prevention also is the best strategy. One way is to plant densely and use groundcovers so there’s no bare soil for spurge to sprout.
A second option is to mulch bare soil. Since spurge seeds need light to germinate, a topping of even two inches of organic mulch is enough to stop this weed.
And a third option is to prevent spurge sprouting with a spring application of a granular weed preventer. Preen Extended Control Weed Preventer, for example, prevents spotted and prostrate spurge as well as 130 other weeds for six months and can be applied over or around some 600 species of existing plants.
Spurges also can be pulled from or dug out of garden beds after they germinate. At least they come out easily since they’re newly germinated annual weeds.
Wear gloves when pulling spurge since some people have allergic skin reactions to the sap in the plants.