Preparing Pastures for Horses

June 8, 2022

Hi, I'm Paige, half of the duo behind Fairway Stables™

This website is the one I've been searching for, for years; a compilation of knowledge on all things horsemanship, including practical advice on how to start an equestrian business.

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Preparing Pastures for Horses

One of the most important aspects of horse ownership, and horsemanship, is ensuring that your horses have a safe pasture to live in. Seemingly simple, quite a bit goes into figuring out exactly what makes a pasture safe for horses. Read on for a breakdown of preparing pastures for horses!

Table of Contents

How much pasture space does a horse need?

If you are preparing a new pasture for your horses, a good first step is to determine how much pasture space your horses need. A general rule of thumb is to have 1 to 2 acres for your first horse, and an additional acre for each additional horse. For example, you would generally want at least 5 acres for four horses. 

There are a few other things to consider when picking the perfect pasture for your horses, including overgrazing, overeating, and nutrient deficiencies or harmful substances in the pasture. 

Avoid Overgrazing Your Pasture

To prevent overgrazing, you will need to limit the number of horses on your pasture and rotate your pastures, too. Horses will graze until the grass is cut down to soil level. This could cause the grass to burn up and dry out in hot temperatures. If you have too many horses in too small of an area, you also run the risk of compacting the soil down to the point that only very aggressive plants like weeds can grow.

Prevent Your Horses from Overeating

Overeating is common for ponies and donkeys as their metabolism is much more efficient at breaking down food than larger horses. You might have to restrict their access to fresh grass to avoid them eating too much and developing health problems like obesity or founder inflammation within the hooves. 

Even horses who have spent time grazing pastures may need an adjustment period if they’ve been eating hay all winter. Colic may occur if their diet is suddenly changed from hay to prolonged pasture grazing. 

Make Sure Your Horses Get the Nutrients They Need

It’s very important to make sure your horses are getting the minerals and nutrients they need from grazing. This can be more difficult than it seems as looks can be deceiving. For example, a very green pasture may just be chalked full of weeds that don’t provide a lot of nutritional value for horses. And as we will discuss below, some weeds like johnsongrass can be highly toxic if eaten in large quantities.

Supplementation is almost always necessary in horses’ diets. While a pasture could be the sole source of nutrition for a horse, it is rare that the soil has everything each individual horse might need. For example, selenium is particularly important for horses yet is scarce in many parts of North America. Levels of this important antioxidant can be replenished with supplements before the onset of conditions like white muscle disease. If your horse is prone to tying up, or painful muscle stiffness after activity, a selenium deficiency might be the culprit.

For horses with laminitis and other chronic conditions, even more specialized grazing practices and dietary supplements may be necessary. Find more on this here.

How do you prepare land for a horse pasture?

Before moving your horses to a new home, it’s important to assess the safety of the new space, including fencing, shelters, and potentially harmful or poisonous plants. To read more about proper fencing and shelter for your horse pasture, check out this article

But today, we will be focusing on a common problem when preparing pastures for horses: johnsongrass. There are lots of different plants and trees that are poisonous to horses, but johnsongrass is one of the most prevalent potential dangers. However, when properly managed, johnsongrass is an acceptable forage option. 

Here’s what you need to know about johnsongrass when preparing pastures for horses.

What Is It?

Johnsongrass is a common perennial weed found across the US, sprouting in early spring. It is sometimes considered a noxious grass because it is a suitable host for several diseases and insects. However, johnsongrass does effectively reduce soil erosion with its high yield of forage and is highly palatable before flowering. It is also one of the most common weeds that farmers face while raising crops from corn and sorghum to cotton and soybeans. 

What Does Johnsongrass Look Like?

Johnsongrass seedlings may be mistaken for seedlings of corn or sorghum, but it has a few distinguishing factors. For example, Johnsongrass has narrower and hairless leaves and stems. In its developmental stages, johnsongrass is marked with a distinctive white vein running down the center of each blade.

Adult johnsongrass plants have a green stalk with branches extending laterally at the bottom of the plant and parallel to the stem at the top, forming a triangular head shape. These plants can reach 7 feet tall with branches reaching up to 1.5 feet long. 

Johnsongrass seeds are tiny, egg-shaped balls that attach to the branches and turn a dark reddish-brown when they are mature. Johnsongrass plants have roots and rhizomes, distinguishing them from similar looking grasses. These rhizomes range from white to brown and often have brown scaly sheaths covering purple dots or nodes.

Can Horses Eat Johnsongrass?

So, can horses graze in a pasture with johnsongrass? Do you need to control it when preparing a pasture for horses? What about johnsongrass hay? It’s best to avoid it. While johnsongrass can be safe for horses to eat under the right conditions, it has the potential to build up poisonous levels of nitrate and prussic acid. These potentially lethal substances occur in johnsongrass plants during periods of regrowth after undergoing stress such as severe drought or frost.

If a horse consumes enough of this toxic johnsongrass, they may suffer from nerve damage known as neuropathy and teratogenesis which can harm the fetus. Other complications such as nitrate intoxication or acute cyanide poisoning are very rare in horses but are more common in cattle. 

Symptoms of poisoning typically surface a few weeks to months after repeated grazing of johnsongrass. Similar symptoms have been linked to the consumption of hay containing sorghums such as johnsongrass. Some horses may improve if johnsongrass sources are eliminated and they receive treatment for bladder or kidney complications immediately after symptoms present themselves. However, there is no specific treatment options for johnsongrass poisoning and the nerve damage it may cause is permanent. 

Unfortunately, there is not much information about how johnsongrass causes these complications in horses nor the amount of johnsongrass that must be consumed to cause serious harm. The process is most closely linked to spinal cord damage that spreads to the bladder and hind regions, causing lack of coordination, incontinence, and reproductive complications for mares such as fetal malformations and abortions.

Johnsongrass Management

Because of the possibility of nitrate toxicity and prussic acid poisoning, most people prefer to control Johnsongrass using prevention practices such as the following:

  1. After a frost or long periods of drought, test the nitrate and prussic acid concentrations of your pasture forage, waiting at least 5-7 days before cutting hay or grazing horses if high levels are detected.
  2. Take extra precautions before grazing if a pasture has recently been treated with nitrogen fertilizer.
  3. Never introduce horses to johnsongrass to avoid harmful health effects.

Preventing Johnsongrass

When preparing pastures for horses use preventative measures to guard against unwanted johnsongrass plants:

  1. Use a weed-free seed when seeding pastures.
  2. Avoid driving machinery through johnsongrass patches to prevent seeds from spreading.
  3. Clean equipment after using it in areas with johnsongrass plants.

If prevention fails or there are established plants in your new horse pasture, a few methods can be used for controlling johnsongrass. 

The easiest and cheapest way to control existing johnsongrass is to continuously mow or overgraze. However, this method does require an understanding of the rhizome energy reserves on the johnsongrass plants. Rhizome energy reserves will be the lowest within the first four weeks of emergence. This is the best time to remove the leaves and stems of the plants by mowing or overgrazing. That’s because the rhizomes will not have a source of energy to replenish their reserves.

You could also take the mechanical control route, though it is typically more expensive. This involves plowing to a depth of 3-5 inches in the fall to reach just below the rhizomes. This brings them to the surface to expose them to inhabitable temperatures. Disking risks an increase in infestations because it cuts the rhizomes into pieces that can spread and sprout into new plants. The trick is to combine this method with an appropriate herbicide. The cuts in the rhizomes will be a better vessel for herbicide absorption.


Take care in preparing pastures for horses. The more you prepare for things like overgrazing, nutrient deficiencies, and harmful plants, the more complications you can avoid down the line. Once you have prepared your pasture, stay vigilant in checking the pasture’s conditions. A simple check can protect the health of your horse from serious issues like obesity, malnutrition, and johnsongrass poisoning.

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