Clover is a plant with many identities. To some it is a weed, to others a desirable part of a home lawn, to others a feed crop and to still others a source of fascination, religious symbolism and perhaps, good luck.
What is Clover?
Clover is a commonly used name for the genus Trifolium, a group of roughly 250 plants that all fall in the legume and pea family. Clovers are native to every continent on the planet with the exception of Australia and Antartica. In the United States several types including white, red and crimson are all commonly grown as feed crops, but in home lawns only one, white clover, makes regular appearances.
White clover is a low-growing plant native to Europe and central Asia. It arrived in the United States with early settlers and quickly spread in all directions. It has a notably shallow root system but spreads rapidly above ground via stolons. It prefers clay and silt soils that are low in nitrogen but relatively high in phosphorus and potassium. Its leaves are its signature and are composed of three, or very rarely four, heart-shaped leaflets.
Due to its pervasiveness clover is easily identified even by those with no lawncare or gardening experience. However, a handful of other plants can easily be mistaken for it. These include yellow wood sorrel and creeping wood sorrel, both of which are types of oxalis. These wood sorrels look strikingly like clover, possessing leaves that are nearly identical in appearance. However, in contrast with white clover which produces dense rounded flowers, wood sorrels have tiny yellow flowers each containing five small petals. Another plant often confused with clover is black medic. However, it grows taller than white clover with longer stems and leaflets that are more oval than heart-shaped.
Does Clover Belong in a Home Lawn?
This is a frequently debated subject and passions run high on either side of the argument.
Without question, clover has certain benefits. Its green color matches many lawn grasses and it maintains that color even during the hottest days of summer when some grasses struggle and begin to fade. It is able to withstand dog urine, something that will kill virtually all desirable grasses. It can grow nearly anywhere outside of dense shade and requires little maintenance; it rarely gets tall enough to mow, it can survive with very little water, and it actually prefers soils that aren’t fertilized.
However, clover also has certain downsides. It struggles under even moderate amounts of traffic. It will not survive in yards that are frequent playgrounds for kids and pets or home to sports played by adults. When it is played on it tends to stain clothing easily and its stains can be difficult to remove.
At the end of the day, clover and grass do not make good partners. When mixed together, clover tends to grow in clumps and patches, this leads to an appearance that many find sloppy or cacophonous. Moreover nearly all grasses – with the exception of centipede – require moderate to heavy applications of nitrogen-based fertilizer in order to thrive. Yet applying nitrogen in even modest quantities will cause clover to struggle and eventually die out. Most grasses will also require herbicides to keep broadleaf and grassy weeds away. It is true that clover will help prevent some of those weeds, at least in the spots where it is densely growing, but weeds will still emerge elsewhere and they can’t be treated with conventional herbicides as those will kill the clover in addition to the weeds.
Ultimately it is best to go in one direction or the other. Either grow a microclover dominated lawn – microclovers being a superior subtype of common white clover – or grow one dominated by grass.
Do Natural Methods Work for Killing Clover?
While there are many natural herbicides on the market that are quite effective they are all non-selective. This means they will kill clover, other weeds, and any desirable grasses as well. Using these to kill small patches of clover might be okay in a warm season yard – meaning one planted to bermuda, centipede, zoysia, St. Augustine or bahiagrass – as these grasses will quickly spread and fill in any dead spots, but in a cool season yard – meaning one planted to bluegrass, fescue or rye – using them will likely require reseeding any areas that were sprayed.
Tips for Preventing Clover
Fertilize your lawn – The easiest way to prevent clover is to maintain a dense, well-fertilized lawn. As discussed above, clover will struggle in nitrogen rich soils, but most desirable grasses will thrive in them. How much nitrogen should be applied will depend on the type of grass planted in the lawn, some grasses prefer more nitrogen than others. When it comes to fertilizer, the recommended maximums should not be exceeded; too much of a good thing can indeed be very bad in this context.
Mow tall – The white clover found in lawns rarely exceeds three inches in height and can be easily shaded out by taller grasses. While different grasses should be mowed at different heights – ranging from roughly 1 inch for bermuda to up to 4 inches for St. Augustine and tall fescue – it is always best to mow at the higher end of any recommended range.
How to Get Rid of Clover
STEP #1 – Get the right products and tools
Clover is easily damaged by many herbicides but its aggressive growth habit can often allow it to recover and return to the lawn. Eradicating it requires choosing the correct herbicide and applying it precisely. For cool season lawns, the best herbicide to use on clover is triclopyr. Triclopyr can be found as a standalone product or in blends where it is combined with other herbicides. I prefer blends as they fight dozens, if not hundreds of weeds with multiple modes of action. My favorite triclopy-containing four way is T-Zone, a devastating product that makes quick work of clover and other broadleaf weeds. However, there are situations where using T-Zone or other blends is not advised, most particularly in lawns with exposed tree roots. Most blends – including T-Zone – contain the herbicide Dicamba which can be absorbed by exposed roots and cause severe damage to the trees that have produced them. In cool season lawns with exposed roots, it makes sense to use triclopyr as a standalone product – this one from Hi-Yield is excellent – or combined in a homemade blend with Tenacity.
Triclopyr is not safe on warm season grasses and should not be used on any lawn containing them. For these grasses I recommend SpeedZone Southern to control clover. This is a four way blend made by the same company that makes Trimec Southern, a product that I have recommended in other posts. Trimec Southern is also quite effective on clover so it is already in your arsenal, there is no need to purchase an additional product. SpeedZone Southern is safe on all warm season grasses except for the Floratam and Bitterblue varieties of St. Augustine. For those grasses, I would recommend using Dismiss to kill clover.
|Cool season lawns (rye, bluegrass, fescue)||Warm season lawns (bermuda, zoysia, centipede, St. Augustine)||Warm season lawns (Floratam St. Augustine, Bitterblue St. Augustine)|
|T-Zone||SpeedZone Southern||Dismiss Turf Herbicide|
All of these herbicides will require a sprayer to apply. Sprayers come in all shapes and sizes ranging from small, hand-carried pump sprayers suitable for small lawns, to backpack sprayers suitable for medium sized lawns to push sprayers for large lawns or even tractor-pulled models for the largest ones. No matter what sprayer you choose, equipping it with a high-quality fan-tip nozzle is important when targeting weeds.
Having a sprayer suitable to your lawn is essential for proper lawncare. It is useful not only for applying clover-killing herbicides but also for applying crabgrass-preventing pre-emergents, soil-benefiting humic acid and various other products. There are granular herbicides on the market, usually coupled with fertilizers and sold as “Weed and Feeds.” However, these products are notorious for providing mixed results when it comes to weed control. Those who are looking for the convenience and time-savings that these products provide would be better suited by making their own Weed and Feed by combining one of the previously recommended herbicides with liquid fertilizer or by buying a premixed liquid Weed and Feed.
STEP #2 – Pick the right time
For clover and other weeds to be susceptible to herbicides they need to be in a stage of active growth. For clover this means that daytime temperatures should be at least 60°F. Spraying them when temperatures are colder will lead to an incomplete uptake of the herbicide and lackluster results. However, spraying weeds when temperatures are too hot can also be problematic. When applied in times of high heat, many herbicides will damage desirable grass in addition to killing weeds. For T-Zone temperatures should not exceed 85°F, for Hi-Yield Triclopyr, SpeedZone Southern and Dismiss they should not exceed 90°F.
Herbicides should not be applied lawns that are wet. Dew, rain or irrigation water can all dilute even the best products and prevent them from sticking to the weeds. Thus, grass should be dry and no rain should be forecast for at least 12 to 24 hours.
When spraying most weeds it is advised not be mow the grass beforehand as reducing the size of the weeds makes for smaller targets for herbicides. However, when fighting clover mowing beforehand is a good idea as tall grass can actually prevent the herbicides from reaching the low-growing clover. Mowing, however, should be avoided for at least 24 hours after the application so as to allow ample time for the product to work its way into the clover.
STEP #3 – Mix and spray herbicide
To create an herbicide mix, begin by adding half the water called for on the herbicide’s label to the sprayer. Then add the specified amount of herbicide and mix with a manual or drill-attached paint mixer or by simply shaking the sprayer. Then add a surfactant, if needed – of the recommended herbicides in this post, only the Hi-Yield Triclopyr would benefit from one – and mix again. Finally add a marking dye – a helpful addition that reminds you what clover you have sprayed and what you haven’t – and the remaining water and mix a final time.
The lawn can either be sprayed in its entirety – a technique called broadcast spraying – or specific patches of weeds can be targeted – a technique called spot-spraying. Spot spraying is the better and more responsible choice in most situations; broadcast spraying should be limited to enormous lawns where spot-spraying is impractical or to lawns with a massive and far-reaching infestation of weeds. Note that herbicide and water ratios may differ depending on whether one is broadcast or spot spraying; always refer to the herbicide’s label for the correct amounts of each.
When broadcast spraying the herbicide mixture should be applied evenly over the entire lawn. This is easier said than done and beginners are best served by practicing with water a few times first. When spot spraying clover should be sprayed until it damp but not to the point that it is dripping. More is not better in this context as excessive amounts of herbicide can damage desirable grasses.
Read any article on clover and you will hear this mantra repeated endlessly: keeping clover in the lawn will improve soil fertility as clover will pull nitrogen from the atmosphere and make it available for nearby plants.
The truth is more complicated. Clover, like nearly all legumes, has nodules on its roots that provide a home for rhizobia, a bacteria capable of taking atmospheric nitrogen and transforming it into ammonia via a process called nitrogen fixation. From there, another bacteria, nitrosomonas, converts the ammonia to nitrite, and still another, nitrobacter, converts nitrite to nitrate which can then be used by plants.
The question at hand is does the nitrogen that is fixed by clover make it way to grass? The answer is yes but in VERY limited amounts. Research has shown that the amount of fixed nitrogen made available to nearby grass is in the 4-14% range. Thus, in order for clover to provide adequate fertilization to grass one need to grow a lot of clover and very little grass.
While, yes, clover seed was included in some grass seed mixes for many decades prior to the advent of selective herbicides in the years after World War II, this misses a critical point: such mixes contained all sorts of weed seeds as there was no effective means of controlling any of them even on grass seed farms. The fact of the matter is that before the 1940s there were no effective herbicides of any sort. Even in agriculture there were few options for getting rid of weeds. Tilling was, and in some places still is, a common method. 19th century farmers tried various salts and acids but few of these were effective and none of them were selective. The popularization of 2, 4-D – the first selective herbicide – after the War revolutionized not just lawncare by agriculture as well. This revolution did lead to clover’s decline in home lawns but many people still like it and it is planted regularly. The difference is that in times past clover appeared whether it was wanted or not; now the homeowner has a choice.
White clover first flowers in the spring but will continue to do so throughout the summer.
Bees do like clover and will visit it regularly. This can be considered both an argument for and against including clover in the home lawn. On one hand, bee populations are declining and ensuring they have an adequate supply of desirable flowers is essential to their recovery. On the other hand, a lawn full of bees can be problematic, particularly when children are playing in the yard. A compromise might be to keep clover out of the lawn but to plant bee-friendly flowers like sunflowers, daisies and marigolds in flower beds located elsewhere on the property.
Clover mites are tiny insects that feed on clover and lawn grasses – among other plants – during the warmer months of the year. The damage they do to plants is very minimal and they are not dangerous to humans or pets. However, they are capable reproducing in massive numbers and are sometimes known to invade homes. While even inside the home they do not present a danger, their presence in large numbers can be unsettling. Most of the time they will congregate on window curtains and other fabrics where they can be easily dispensed with using a vacuum cleaner. If an insecticide is desired, Permethrin is a safe and effective one to spray indoors to combat them.
It is commonly said that the chances of finding a 4 leaf clover are 1 in 10,000; this is an exaggeration, the actual odds, while still not great, are about 1 in 5,300. Good luck in your search!