Should We Mow Our Pastures?

In the fourth installment of our new series, Where’s the Grass?, we share that while you don’t always need to mow your pastures, there are times that it needs to be done.

This is the latest installment in the “Where’s the Grass” series. Older iterations may be found archived on the Small Farms website, at smallfarms.cornell.edu. You may also find a collection on beef cattle management, the “Where’s the Beef” series.

The question always seems to come into discussion in grazing circles as to whether you should mow your pastures as a routine practice. The short answer is “It depends”. Mowing pasture paddocks entails using any of a variety of machines to cut back weeds, to cut off weed seed heads before they mature, and to make better conditions for the grass plants to grow.

This is why we brush hog pastures and hayfields. After brush hogging, the grass will grow back very nicely.

We need to keep in mind that mowing pastures entails an expenditure of time, labor, fuel, and machinery operation. Machinery operation means that the machinery is being depreciated that much more, the more you mow. When machines wear out, they break down and must be repaired or replaced.

The need definitely exists however, to mow pastures in certain circumstances. When is the best time to mow? Probably right after the animals are through grazing a paddock. This will give the grass time to regrow. If you wait too long to mow after grazing, then you are cutting into your next rotation’s supply of grass.

Why do we mow? The most important reason is to stem the growth of weeds. Some pastures can look horrible with weed infestations. There are other ways to control weeds, however. You can mob graze sheep and goats if you have them; they are both grazers and browsers and can make short order of many common weeds. You can also spray for weeds, if that is your inclination. I only suggest that you absolutely know what you are doing to ensure accurate coverage. If you are organically inclined, this will not be an option, and then we will be back to mowing.

Another good reason to mow pastures is in the reclamation process. If a field has been abandoned or has not had any haying or grazing occurring in a while, then mowing can kill off those existing weeds. You must keep your soil pH at least up to around at least a 6.2 level. Nature abhors a vacuum, and when the ground is not covered, she will swoop in and have weeds proliferate, especially when the pH is below 6.2. By keeping pH levels up , and fertility levels up, the grasses will stand a much better chance at survival.

Another time that mowing pastures and hayfields occurs in years much like 2025. We had 2 continuous months of solid almost daily rain, making it all but impossible to make dry hay. Making silage and baleage was challenging enough too! As a result of this aggravating rain pattern, we had a lot of very low quality hay accumulate in fields well into late July. If we don’t want to make hay out of this stuff, then we can mow it, or brush hog it, and let it recycle as organic matter, providing nutrients for later growth.

The author’s ten foot brush hog which attaches to the drawbar, and is raised and lowered hydraulically.

What can we mow the weeds with? Normally we would use some sort of brush hog, the technical name of which is “rotary mowers”. (Bush Hog is a brand). You can also use an older haybine, or a mowing machine. You can use your disk bine that you mow all of your hay crops with. I prefer not to do that as a diskbine is a very high value implement that we need to keep operational for mowing hay crops and we don’t need to be sacrificing it with the rougher application of brush hogging. You can also use disk mowers, which are like diskbines, but do not crush the hay. There are also machines known as rotary mowers, which do an excellent job but they tend to be of short width, typically 5 or 6 feet.

So how big of a brush hog should you use? I would suggest as big as your tractor can easily run without overloading the tractor. Brush hogs can vary in width from about 5 feet all the way up to fifteen feet. The largest mowers are known as “bat wing” mowers, whereby two sections on either side of the machine are raised hydraulically and then lowered when its time to mow.

The reason that I suggest using as big a mower as your tractor can operate is due to the oftentimes excessive amounts of time that it takes to accomplish all of this brush hogging. My bigger brush hog is ten feet in diameter, and it always seems to take inordinate amounts of time to get all of my brush hogging done. I have a small, older brush hog that is seven feet in width that is mounted on one of my smaller tractor’s 3 point hitches. This is a dandy outfit to operate in close quarters but is certainly not ideal for bigger acreages.

I would also suggest that you buy as good of a quality brush hog that you can afford. They can be extremely expensive, but you want to shy asway from the cheap, imported machines that you find at the typical big box farm store. The problem is that these imported machines change manufacturers every few years or so and finding parts for them can be difficult in years to come.

So how often should you brush hog? If you’re going to do this, it’s probably good enough to at least do so once per year, typically after the first grazing. You don’t have enough time to mow more than this anyway, what with managing all of your hay crops, and correctly managing your rotational grazing system, working a job off of the farm, etc. Keep in mind that there are many grazers who do a top a notch job in managing their pastures and do little or no mowing/brush hogging. I mow mine when I can get around to it!