Video Transcript

Black Medic, also known as hop medic or black clover, is a broadleaf weed that can quickly take over lawns, gardens, and fields. This yellow-flowering weed forms dense mats that can smother your turf if left unchecked.

You’ll often find Black Medic in dry, compacted, low-nitrogen soil and places where grass struggles to thrive. It has a deep taproot, trifoliate leaves that grow in groups of three, and has clusters of small, bright yellow flowers at the end of each stem. It flowers in the spring and summer, typically from April to July. The flowers are then replaced with pods that contain the seed.

Because Black Medic can create its own nitrogen, its presence often signals that your lawn needs more nutrients. Start by testing your soil and addressing any nitrogen deficiencies with proper fertilization. Aerating compacted areas in your lawn and improving drainage will also make your grass stronger and more competitive against weeds.

If you already have Black Medic, use a selective post-emergent herbicide labeled for broadleaf weeds while the plant is actively growing in late spring or early summer. Consider applying a two-way or three-way herbicide containing the active ingredients 2,4-D, dicamba, MCPP, and triclopyr, in cool-season turfs only, when looking to effectively control black medic weeds in turfgrass. Fluroxypyr is an option that is often found in herbicides that are labeled for pastures and right of way areas. Always check that the product is safe for your turf type before applying.

To prevent it from coming back, apply a pre-emergent herbicide in early spring and again in fall before new seeds can germinate. Look for pre-emergents with proven active ingredients dithiopyr and isoxaben that are effective against broadleaf weeds. Consider a split pre-emergent strategy: apply your pre-emergent twice in the spring and twice in the fall, spacing each application 6–8 weeks apart. Always follow the product label for exact timing and application rates.

By combining the right herbicide treatments with a solid lawn care routine like fertilizing, watering, and aerating, you can keep Black Medic from returning and maintain a thick, healthy, weed-free lawn. And it's that easy with the expert help from DoMyOwn.com. Subscribe to our channel for more DIY and product videos.