Yes, Oxalis weed has little yellow flowers! Oxalis flowers have five petals that bloom from spring to fall. Remember, though, however beautiful, yellow flower weeds in grass are problematic for a number of reasons. As a perennial weed, Oxalis genus reemerges each spring to colonize vacant spots in lawns quickly.

With leaves similar in appearance to clover, many people think they’re looking at clover with yellow flowers when they see Oxalis for the first time. To determine if your yellow clover looking weed is Oxalis or clover, try looking at the leaves first. Both plants have green leaves that grow in groups of three (sometimes four), but clover leaves are rounded, and Oxalis leaves are heart shaped.

Sometimes, Oxalis leaves can also boast a purplish cast. At night, or when stressed, the crease within Oxalis leaves allows them to fold in half. While usually low growing, some Oxalis species can reach as high as 15 inches tall. Deep taproots make hand-weeding Oxalis very difficult. If stems break off when pulled, the plants have no problem regrowing – even if no foliage is left.

Two types of Oxalis are common to our area: Creeping Wood Sorrel and Yellow Wood Sorrel. However, there are hundreds of known species.

Creeping Woodsorrel Oxalis grows from bulbils and is a sour grass native to North America. Mature Creeping Woodsorrel plants often grow in small clumps, mounded to about 4”-8” high. As with the description above, you’ll find its flowers are made up of 5 petals and 5 stamens, though Creeping Woodsorrel petals remain separated from each other all the way to the base.

Yellow Woodsorrel (Oxalis stricta) weed tends to grow more upright and is known to reach heights of up to 15” tall. Its seed pods point upward rather than down, like many other species, and stems grow out at sharp angles. You’ll find Yellow Woodsorrel in lawns, gardens, and wide, open spaces such as fields and meadows.

Regular fertilization and watering will ensure your lawn grows thick and strong. Thick lawns crowd out potential weeds and prevent seeds from germinating in turf. Allowing your grass to grow high – up to 3 or 4” is ideal as it reduces stress and prevents sunlight from reaching down to weed starts. A herbicide toward the end of winter is a great way to prevent oxalis from even starting.

Try watering your grass more infrequently, but deeply. This will encourage your lawn’s roots to grow deeper and allow it to withstand yellow flower weeds in grass. Preventing Oxalis is an important step, but, if you already have them, Senske understands how to kill Oxalis and prevent them from returning again. If you need the best Oxalis Weed killer, read on.