How To Identify and Control Black Medic Weed In A Lawn | A Comprehensive Guide

If you are the type of person who likes to spend as much time as possible outside and on your lawn, there is a good chance that you resent the sight of weeds growing in your grass. They are embarrassing and an eyesore. They frequently stand out from the rest of the grass and feel like a disgrace. However, some weeds, such as Black Medic weed, blend right in with the grass and disguise themselves as something more familiar.

Black medic weed

Photo Credit Black Medic is a spreading, low-growing weed frequently seen in pastures or lawns.

Medicago lupulina, more commonly known as Black Medic, is a widespread, low-growing broadleaf weed found throughout the United States and Southern Canada. This plant is a member of the Fabaceae family and is native to temperate regions of Asia and Europe.

In most cases, the Black Medic plant is not discovered until after it has produced a large number of yellow blooms shaped like a clover.

Flowers give way to seed pods that mature to a dark black color and remain attached to the prostate, dark brown to black stems. This weed can frequently be found growing in dry and marginal soils, typically with thin turf that has not been fed with nitrogen.

It Is A Blessing In Disguise!

Unbelievably, you might end up appreciating that Black Medic has invaded your yard. The appearance of Black Medic in the yard indicates an underlying issue with the soil.

So, once you understand why Black Medic grows in a yard, getting rid of it won’t be difficult, and the improved soil quality will come as a welcome bonus as it fixes nitrogen in the soil.

Black Medic Identification & Quick Facts

Identifying black medic weed

Photo Credit Black Medic has teardrop-shaped leaves with yellow-colored flowers.

Black Medic is a noxious weed that goes by several names, including Yellow Trefoil and Yellow Clover. The Black Medic plant is characterized by its lengthy taproot, which can penetrate most soil types.

In addition, several trailing branches that are slightly hairy emerge from the base of the plant. The plant spreads to a maximum height of two feet and grows low to the ground; however, it does not root along the stems. 

Nevertheless, it features teardrop-shaped leaves that are common on clovers, but unlike other clovers, it has yellow blooms.

The leaves, however, are oval and grow in groups of three, just like the leaves of many clover types. Individual leaflets have smooth base edges with a minor serration at the top and a short spur at the tip.

Scientific NameMedicago lupulina
Other Common NamesYellow trefoil, Hop clover, Nonesuch, Black hay, Black clover, Hop medic, 
Life Cycle– Summer annual or winter annual- Sometimes, short-lived perennial
HabitatVegetable and agronomic crop fields, orchards, gardens, lawns, vineyards, Grassland, pastures, roadsides, and other disturbed, unmanaged places.
Growth FormHerbaceous
Growth HabitProstrate
Growth Rate– Rapid Germination
– Moderate to rapid spread
Height0.5 to 2 feet
Width0.25 to 2 feet
Leaves– Compound pinnate
– Cuneate base
– Lightly serrated at the tip of the margin
– Ovate or obovate
– Three leaflets
Fruit– Slightly hairy
– Pods shaped like kidneys
– Single seeded
Flowers– Bloom from March through August
– Small, oblong heads of 10 to 30
– Yellow
RootDeep taproot, fibrous network

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Where Is Black Medic Found?

Where is the Black Medic weed

Photo Credit In lawns, the presence of Black Medic is an indicator of low soil nitrogen levels.

Like many other drooping plants that grow low on the ground, Black Medic can thrive under challenging conditions. It thrives in full light and is usually spotted in the summer, growing in regions where turf grasses do not thrive.

Therefore, if you find Black Medic growing on your lawn, there is a good chance that your grass is becoming weaker.

It is most commonly found as a weed in dry, sunny locations in turf and waste ground. However, it can also become a nuisance in gardens and fields as well.

In lawns, the presence of Black Medic, which is able to outcompete less vigorous grasses, is usually an indicator of low nitrogen levels in the soil.

Black Medic Vs. Clover

Vs Clover

Photo Credit Unlike clovers with many different colored flowers, Black Medic will always have yellow flowers.

At first glance, the Black Medic resembles a clover. This is why it frequently goes undetected and untreated by homeowners who are aware of the benefits of having clover on a lawn.

So, how exactly do you differentiate between the two? To begin, if you examine the patterns found on the leaflets of Black Medic, you will find that the center leaflet has a short stock, while the other leaflets droop more laterally towards the stem.

Moreover, the leaf edges of the Black Medic are pointed and have a tooth-like appearance. Another way to distinguish them is by their blossoms. Flowers of the clover are typically white, although they can also be pink, purple, or even scarlet. On the other hand, Black Medic weed will frequently produce little yellow flowers.

RELATED: Common Lawn Weeds and How To Identify Them | A Comprehensive Guide

How To Get Rid Of Black Medic?

Before you start spraying chemicals or crawling around on your hands and knees to get rid of Black Medic, you should familiarize yourself with the conditions in which it thrives.

Compacted soil and soils deficient in nitrogen are ideal conditions for the growth of Black Medic. This is why you will most often see it along a roadside or a sidewalk, both of which have been subjected to heavy foot and wheel activity, which has compacted the soil. 

If you find Black Medic growing in your yard, lawn, or garden, you should first attempt to fix the compaction issues and get a soil test done rather than immediately soaking the area with herbicides. A soil test will give you a better understanding of what nutrients are lacking in your soil and what you need to add to your garden to improve its condition.

However, if resolving compaction and fertility issues does not work, there are many ways (organic and chemical) that you can employ to get rid of Black Medic.

Natural Ways To Get Rid Of Black Medic

Natural and organic weed control methods, in contrast to pesticides, can zero in on the source of the problem while leaving the surrounding region unaffected. However, employing natural management means more manual labor than herbicides. 

Nevertheless, the following are a few natural and organic approaches that you can take to eliminate Black Medic from your lawn.

Hand Pulling

Hand Pulling

Photo Credit Weeds should be pulled out while they are still young and before they have set seeds.

If you find that your lawn has been infested with weeds, one of the most effective ways to get rid of them is to roll up your sleeves and go to work picking them out.

This backbreaking labor may be made easier with the use of hand tools such as shovels, trowels, and hand weeders, particularly for weeds with deep roots.

Also, it would help if you pulled the weeds when they are young, before they have deep roots or set weeds.

Personally, I find Black Medic to be one of the easiest weeds to uproot by hand. This is because it has a propensity to grow together in a centralized location, which makes it much simpler to control and eliminate than it would be otherwise.

However, still don’t just let the weeds you pluck sit there on your lawn; instead, put them in a bag when you pull them out.

RELATED: Common Types of Sticker Weeds (and How To Get Rid Of The Sticker Weeds)

Smother The Weeds

Smother weeds

Photo Credit Smothering is the process of covering weeds to block off light and air.

Your first defense against weeds, particularly annual and biennial weeds, should be to take them out by hand or plow them over. However, you can try smothering the Black Medic Weeds growing on your lawn if you believe manually removing them is too difficult.

In areas that will be planted in the future, smothering is an efficient method for eliminating weeds. Start by mowing the lawn. Once you have mowed the area or chopped off the top growth, apply a layer of mulch made of heavy cardboard, newspaper, or black plastic. 

To prevent weeds from growing through the crevices, these materials should be overlapped. The best time of year to eradicate Black Medic using this method changes based on the climate, the time of year, and lawn conditions. 

If your garden is overrun with abundant Black Medic plants, it is best to suffocate the weeds as soon as possible. Otherwise, it may take significantly more time to de-weed the garden and prevent the Black Medic from sprouting back. 

After the smothering materials have been placed, they should be fixed in place using weight or spikes, so they don’t shift or get blown away.

Solarizing Black Medic

Solarizing Black Medic

Photo Credit Solarization is the process of heating the ground to kill lawn weeds or any other vegetation.

Solarization can be an excellent way to control several weeds, including Black Medic, Bindweed, and any other annual weed.

Bear in mind, however, that many of these weeds have vast root systems, and many of them re-sprout even after being exposed to extremely high temperatures. The method entails covering the ground with a tarp, which is often a cover made of transparent polyethylene, and the goal is to capture solar radiation.

The sun generates enough heat to raise the soil’s temperature to levels sufficient to kill weeds, weed seeds, bacteria, and fungi.

Therefore, solarizing is most effective on heavy soils, such as those composed of clay, loam, or a combination of the two. This is because these soils produce a lot of steam when heated. On the other hand, solarization may not be as successful on sandy soil since it drains more quickly and generates less steam. 

Also, keep in mind that solarization eradicates all forms of plant life. So, areas that were previously overrun by weeds will need to have new grass put in them.

Chemical Ways To Get Rid Of Black Medic

Sometimes, natural and organic methods are not good enough to remove Black Medic from a lawn or the infestation is too large to be controlled with the methods mentioned above. In such instances, you can use chemical herbicides. 

Also, it is essential to keep in mind that it is always a good idea to test the effectiveness of the herbicide in a small area to ensure that it will not affect other areas of your lawn.

Nevertheless, there are two distinct kinds of herbicides that can be applied to lawns in order to eradicate and keep Black Medic under control.

Pre-Emergent Herbicides

The use of pre-emergent herbicides is an effective method for preventing the recurrence of Black Medic each spring. As the name implies, preemergence herbicides eliminate weeds before they even emerge or sprout on your lawn. 

Pre-emergent herbicide choices are restricted to dithiopyr (Dimension), oxyfluorfen, and oryzalin when dealing with Black Medic (Rout).

Post-Emergence Herbicides

Post-emergent herbicides are applied to a lawn after the unwanted plant has already germinated, grown, and established a root system. When it comes to controlling Black Medic, the post-emergence herbicides that have proven to be the most successful are those that include the active ingredient clopyralid, fluroxypyr, or quinclorac.

How To Prevent Black Medic From Returning?

Black Medic and other annual weeds will appear anywhere where your grass is not competing. It’s possible that you’re cutting your grass too short, or the grasses you have are too old and feeble and therefore don’t fight much. 

There is also the possibility that the soil is hard and compacted. 

Fortunately, there are a variety of approaches that can be taken to address the problems that can be the cause of the Black Medic on your lawn.

Mow Correctly

Cutting your grass too short or cutting it too short too soon will cause it to grow more slowly. This will give weeds an advantage over your lawn in terms of competition. So, when you mow your grass, be sure you do so at the appropriate height.

Keep The Lawn Soil Healthy

Given that Black Medic thrives in densely packed soil, we recommend you aerate your lawn soil. Additionally, enrich your soil with beneficial organic matter and nutrients. They will act as a fertilizer, encourage grass growth and keep Black Medic out.

Reseed Patchy Areas

Sometimes the issue is not soil compaction but a patchy turf that provides a welcoming ground for Black Medic and other lawn weeds. You can fix this problem quickly by overseeding the patchy areas in your yard. 

Final Thoughts

You can treat Black Medic weed on your lawn the same way you treat any other weed. Once the weed has been identified, the best line of action will be to remove it, followed by taking measures to prevent its return. I always say – the best defense against weeds is a good offense! So, keep your lawn healthy, dense, and well-fed, and you might never have to deal with Black Medic or any other weed for that matter.

Frequently Asked Questions (FAQs)

Why is it called Black Medic?

Beginning in the spring and continuing all the way through autumn, Black Medic will produce a dense and compact cluster of little yellow blooms. As soon as the flowers have reached full maturity, they will develop an exceptionally tightly coiled black seedpod; this is where the name “Black Medic” comes from.

What is Black Medic good for?

Evidence suggests that Black Medic extract possesses antimicrobial properties and may be helpful as a mild laxative. In addition to this, it makes a nutritious feed for cattle and is sometimes cultivated for use as a pasture or cover crop.

Is Black Medic edible?

The blooms and young leaves of Black Medic are edible, as are the seed pods, which can be processed into flour. Also, animals find Black Medic to have a pleasant flavor, providing a decent amount of fodder value, with protein concentrations ranging from 8% to 12%.

Does Black Medic fix nitrogen?

Since it is a legume, Black Medic can incorporate nitrogen from the air into the soil. Its roots contribute nitrogen to the soil by forging a partnership with rhizobial bacteria. As a result, Black Medic can grow where there isn’t enough nitrogen in the soil outcompeting weak grasses.

Sources for Further Reading

Black Medic – University of Maryland Extension Service

White clover and black Medic infesting turf – Michigan State University Extension Service

White Clover and Black Medic Control in Lawns – Colorado State University Extension Service

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