Quick answer: Net wrap doesn't "breathe" like a cloth, but its open mesh is nowhere near airtight — so a properly cured bale keeps releasing its leftover field moisture as vapor, and the tight, smooth skin sheds rain far better than twine. What net wrap won't do is dry out hay that was baled too wet, or make a bale waterproof. Bale at the right moisture (about 15–18% for dry round bales), keep bales off wet ground, and net wrap holds outdoor dry-matter losses to roughly 5–7% — versus 11% or more for twine.
It's one of the most common questions we get from hay producers: does net wrap breathe, and will a bale still dry and shed water under it? The short version is yes on both counts — but with important limits that decide whether your bales come through a wet season tight and green or spoiled on the bottom.
Here's exactly how net wrap handles moisture, rain, and drying, based on extension research and what real producers report in the field.
Does net wrap actually "breathe"?
Net wrap is a knitted high-density polyethylene mesh — mostly open space, laid on the bale in about 2.5–3 wraps. It is not a sealed membrane. Air and water vapor pass straight through the openings, which is exactly what you want on dry hay. The wrap holds the bale's shape and forms a smooth skin while still letting the bale's residual moisture escape as vapor.
This is the key difference between net wrap and the plastic film used for baleage. Silage film is airtight on purpose — it seals oxygen out so the forage ferments. Put that airtight film on dry hay and you'd trap moisture and grow mold. Net wrap does the opposite: it breathes. That's why net wrap is for dry hay and dry straw, and film is for wet, fermented forage. (If those categories are fuzzy, see our guide on baleage vs haylage vs silage.)
Producers see this play out at feed-out. As one grower summed up a long thread on whether hay keeps drying under mesh, a net-wrapped bale made at the right moisture will "sweat out" and cure just fine because the wrap lets it breathe (HayTalk: will hay dry through netwrap).
Will a bale keep drying under net wrap?
A little — and only a little. The normal post-baling "sweat" (the last bit of field moisture equalizing through the bale) escapes as vapor through the mesh. That's the same sweat we cover in does hay sweat after baling, and net wrap doesn't block it.
What net wrap will not do is rescue hay that went into the baler too wet. The wrap adds no drying of its own — it simply doesn't get in the way of the small amount of curing a bale does on its own. Bale at 20%+ moisture and you'll get heating, mold, and dry-matter loss no matter what's on the outside. The safe target for dry round bales is about 15–18%; see baling moisture for net-wrapped bales for the full breakdown.
The old baler's-rule-of-thumb that producers repeat is: rain goes in as a solid and leaves as a vapor. A rained-on outer shell can dry back out because the mesh breathes — but only if the core was dry to begin with.
Does net wrap shed rain?
Yes, and this is where net wrap earns its keep outdoors. It sheds water better than twine for two reasons:
- A tight, smooth skin. Net covers the whole barrel of the bale in one continuous surface, so rain sheets off and runs down instead of pooling.
- Compressed outer hay. The wrap pulls the surface hay tight, closing off the channels that would otherwise wick water into the bale.
Twine can't match that. It leaves bands of exposed hay between the strings — those ridges soak up rain and the valleys funnel it straight into the bale. The result shows up in storage losses. Extension trials consistently find that round bales stored outside lose roughly:
| Wrap type | Typical outdoor dry-matter loss |
|---|---|
| Net wrap | ~5–7% |
| Plastic twine | ~11% |
| Sisal twine | ~15–20%+ |
Those figures line up with university extension storage studies, and we walk through the full cost comparison in net wrap vs twine.
One caution: shedding is not sealing. Net wrap sloughs off most of a rain, but in a long soaking rain the outer inch or two of the bale will still take on some moisture. It's water-shedding, not water-proof. That gap is exactly why premium film-bonded products like B-Wrap were developed to add a true water-shedding layer over the mesh (HayTalk: water-shedding netwrap) — useful information, but standard quality net wrap already sheds far more than twine for a fraction of the cost.
Net wrap vs twine after a rain — which dries faster?
When producers compare bales side by side after a storm, the consensus is clear: net-wrapped bales shed most of the rain and the smooth surface dries back out quickly, while twine bales soak water in the exposed ridges and stay wet longer (HayTalk: which dries faster after rain, netwrap or twine).
Net wins on shedding and re-drying the surface. The one place it can't help is the bottom — a bale sitting in mud with a wet base won't dry from below no matter what's wrapped around it. Which brings us to the most important limit of all.
Where net wrap won't protect the bale
Net wrap manages rain from above. It does nothing for moisture coming up from the ground — and that's where most outdoor spoilage actually happens:
- The bale bottom wicks ground moisture. Set a bale in grass or mud and the bottom third can rot while the top stays perfect. Store on a well-drained rock or gravel pad, on old pallets, or on a crowned, dry site. See round bale storage base prep and storing net-wrapped bales outside.
- Bad stacking traps water. Nestling round bales side by side creates crevices that hold rain against both bales. Line them end to end in single rows, leave a gap for sun and air, and run rows north–south.
- UV breaks the wrap down. A full season in the sun degrades unstabilized mesh until it sheds poorly and shatters at feed-out. Use a UV-stabilized net — details in UV protection and bale net wrap.
How to get the most water-shedding out of net wrap
You can stack the odds in your favor:
- Bale dense. A hard, smooth bale sheds water; a soft, fuzzy one lets rain grab hold. Set your baler for a firm outer shell.
- Cover edge to edge. Make sure the net reaches full width with 2.5–3 wraps and no bare shoulders. For bales you'll store outdoors unprotected, add an extra wrap — see how many wraps per bale.
- Use a quality, UV-stabilized net. Consistent knit and full spread give you the smooth, complete skin that actually sheds water. Our XES Extreme Bale Net Wrap ships factory-direct with free US shipping.
- Get bales off the ground — and top-cover or shed them if you can.
Get the wrap right for your baler
Net only sheds water if it fully covers the bale. Match the width to your machine with the Bale Net Wrap Size Finder, or read how many wraps per bale to dial in coverage.
Frequently Asked Questions
Does net wrap breathe?
Yes. Net wrap is an open knitted mesh, not an airtight film, so air and water vapor pass through it freely. That lets a dry bale finish curing and release its leftover moisture instead of trapping it. It's the opposite of the sealed plastic film used for baleage, which is designed to keep oxygen out for fermentation.
Is net wrap waterproof?
No — net wrap is water-shedding, not waterproof. Its tight, smooth surface sheds most of a rain and runs it off the bale, but in a long soaking rain the outer inch or two can still take on moisture. It still protects far better than twine, which lets water wick in between the strings.
Will hay dry through net wrap?
Net wrap won't dry hay that was baled too wet — it adds no drying of its own. What it does is let a properly cured bale keep breathing, so residual sweat escapes as vapor and a rained-on surface can dry back out. Bale at about 15–18% moisture; the wrap can't fix wet hay.
Will a rained-on net-wrapped bale dry back out?
The surface usually will, because the mesh breathes and the smooth skin sheds most of the water. The critical thing is to keep the bale off wet ground — the bottom wicks moisture from the soil and won't dry from below, which is where outdoor spoilage starts.
How many wraps do I need for outdoor storage?
Most operators run 2.5–3 wraps. For bales stored outside without cover, add an extra wrap for a more complete, water-shedding skin, and make sure the net reaches full width with no bare shoulders.
Does net wrap trap moisture on the bottom of the bale?
The wrap itself breathes, but the bale bottom is in direct contact with the ground and wicks soil moisture regardless of wrap. Store bales on a well-drained rock or gravel pad, pallets, or a crowned dry site to keep the base from rotting.
Featured photo: Net Wrapped Hay Bales by Michael Trolove, licensed under CC BY-SA 2.0, via Wikimedia Commons.
