9 Easy Ways to Store Hay and Keep It Fresh & Mold-Free

What’s the difference between thriving livestock and a barn full of ruined hay? Proper storage.

Improper hay storage can lead to mold growth, nutrient loss, spoilage, and even fire hazards. All of which can cost you money, compromise animal health, and waste months of labour.

You need to know how to store hay correctly because it has a significant impact on feed quality, livestock performance, and overall farm efficiency, regardless of whether you own a commercial farm or a small-scale homestead.

In this article, we will cover everything from choosing a site to stacking techniques and climate considerations. This will give you the knowledge you need to prevent mold and reduce waste from your stored hay.

Why Hay Storage Matters More Than You Think

Hay is harvested forage, typically grass, alfalfa, or legumes, that’s dried and baled to preserve its nutrients for long-term use. 

However, even though hay is considered “dry,” it is still very susceptible to environmental factors. A single mistake in storage can change your nutrient-rich bales into moldy, inedible waste.

Poorly stored hay results in:

• mold growth, which is toxic to livestock, especially horses and young animals
• Nutrient loss due to exposure to sunlight, air, and moisture
• Physical spoilage, such as rotting from ground moisture or pest infestation
• Fire hazards caused by internal heating in overly moist hay
• Reduced profitability, since damaged hay must be discarded or sold at a loss

If you’ve invested time or money into quality hay, protecting that investment with innovative storage methods is non-negotiable. Below are some steps you can take to keep your hay fresh and mold-free.

Step 1: Harvest and Bale Hay at the Right Moisture Level

Before storing hay, the baling process must be done properly. Storing hay that’s too wet is the number one reason for mold formation and spontaneous combustion.

Ideal Moisture Levels for Baling

Use a reliable hay moisture tester to check several bales per batch. Moisture levels above 20% are too high for dry storage and should be either dried further or ensiled (as haylage or silage).

Step 2: Choosing the Right Location to Store Hay

Where you place your hay is the single most crucial factor in preventing mold and waste.

A. Outdoor Hay Storage (Budget-Friendly)

Outdoor storage is standard on farms with limited infrastructure. If done correctly, it can work — but it requires extra caution.

• Elevation is critical: Store hay on gravel, pallets, railroad ties, or rubber mats to keep bales off moist ground.
• Choose a high, well-drained area: Water pooling is your enemy.
• Space your bales: Keep at least 18 inches between bale rows for air circulation.
• Use sloped terrain: This allows rainwater to flow away naturally.

B. Indoor Hay Storage (Best Practice)

An enclosed barn or hay shed is ideal for long-term storage.

• Keeps hay dry and protected from weather and UV exposure
• Limit pest access
• Allows for better stacking and airflow control
• Reduces labour during winter feeding

Indoor hay barns pay off in the long term by saving feed, reducing mold risk, and simplifying access during adverse weather conditions.

Step 3: Covering and Protecting Outdoor Hay

When storing hay outdoors, it is essential to protect it from the elements.

a. Tarping Hay Bales

Tarps are affordable but must be used correctly:

• Use UV-resistant, waterproof tarps specifically made for hay storage
• Create a “roof” effect rather than wrapping bales tightly — allow the hay to breathe.
• Leave a 12- to 18-inch gap from the ground to allow for airflow and prevent condensation buildup.
• Use weights or tie-downs to avoid wind damage.

b. Bale Wrap or Net Wrap

Modern round bales often use plastic net wrap or film. While helpful in shedding water, they don’t eliminate the need for elevation or protection.

• Plastic-wrapped haylage bales are stored at a higher moisture level, but they must be airtight to prevent spoilage.
• Punctures in the wrap lead to spoilage and mold. Inspect frequently

Step 4: Ventilation — The Silent Hero of Hay Storage

Moisture that gets trapped inside a stack of hay bales will inevitably cause mold or heating. Ventilation prevents this by allowing warm, moist air to escape and fresh air to circulate.

Indoor Ventilation Tips

• Use ridge vents or gable vents in barns.
• Install oscillating fans in large hay sheds. 
• Avoid stacking bales all the way to the ceiling or wall; leave 6 to 12 inches of space between them.
• If stacking multiple layers, consider using spacer bars or pallets between layers.

In humid climates, mechanical ventilation will be necessary during the summer or rainy seasons to remove excess moisture from the air.

Step 5: Proper Hay Stacking Techniques

How you stack hay bales affects airflow, structural stability, and the rate at which hay deteriorates.

For Square Bales

• Stack using a crisscross “brick” pattern for air gaps
• Stack in pyramids if space allows — helps shed moisture naturally.
• Use spacers between stacks to prevent heat and moisture buildup.

For Round Bales

• Stack flat side down, single-layer if possible.
• If stacking multiple layers, rotate rows 90 degrees.
• Place end-to-end in lines to avoid water pooling in concave areas.
• Store under covered structures or wrap with breathable fabric if inside barns

Step 6: First In, First Out (FIFO) — Minimize Nutritional Loss

Hay naturally breaks down over time. Even when you store it properly, it loses vitamins like A and E. The longer you keep hay, the more nutritional value it loses.

To reduce waste:

• Label bales with the harvest date
• Always use the oldest hay first.
• Don’t stack new hay in front of older hay. Keep the rotation system clear and straightforward.

Remember, A FIFO system lowers the risk of mold or pests developing unnoticed in older bales.

Step 7: Regular Monitoring and Maintenance

If you think storing hay properly is a job well done, then you are wrong! You need to check it regularly to prevent problems from getting worse. 

What to look for:

• Unusual heat in bales (indicates fermentation or potential fire risk)
• moldy odour or visible mold spores
• Discolouration or excessive dust (low-quality hay)
• Rodent droppings, chewed strings, or burrowing
• Tarp damage or roof leaks

If you find signs of heating, separate the affected bales immediately. Hay fires are real and often begin from spontaneous combustion caused by microbial activity in moist bales.

Step 8: Consider Regional Climate and Storage Methods

Where you live should determine how you store hay. There are humid, dry, and cold climates. So you need to store your hay accordingly. 

In Humid Climates:

• Use enclosed barns with mechanical ventilation
• Avoid storing hay outdoors unless necessary.
• Opt for smaller bales that dry faster and are easier to manage.

In Dry Climates:

• Outdoor storage is a practical and cost-effective option.
• Stack round bales in rows and cover them with UV-resistant tarps to minimize spoilage.
• Keep an eye on wind exposure to prevent tarp tearing.

In Cold/Snowy Climates:

• Store your hay near livestock areas to make winter feeding easier.
• Use insulated barns or portable shelters.
• Ensure easy access during snowstorms or freezing rain.

Step 9: Modern Hay Storage Innovations

Technology is helping reduce waste and labour with tools such as:

• Hay Moisture Meters: Essential for testing before baling
• Smart Hay Storage Systems: Automated barn ventilation and climate control
• Wall-Mounted Hay Feeders: Reduce trampling and hay drop while feeding
• Wrapped Haylage: Allows storage of wetter hay in anaerobic conditions, ideal for cattle

Pro tip: Invest in the right equipment for long-term savings, especially if you have large-scale operations. 

Final Takeaway

Storing hay the right way isn’t just about keeping mold away — it’s about keeping your feed nutritious, your animals healthy, and your hard-earned money from going to waste.

Whether you’re stacking small square bales in a barn or managing hundreds of round bales in open fields, applying best practices in moisture control, ventilation, stacking, and monitoring will make a measurable difference.

Don’t let mold, waste, or spoilage eat into your farm’s profits. With proper planning and regular maintenance, your hay can stay fresh, safe, and nutritious throughout the year.

Ready to cut down on hay waste and make feeding more efficient?

Then visit HayBoss Feeders to explore their innovative hay feeder solutions designed to reduce spoilage and save you money year-round.

Smart hay storage starts with the right tools. Make HayBoss part of your barn today!