Storing Hay and Straw without Spoilage

By How to Inspect a Timber Barn for Rot
Comments 35
2 Jul 2026

Storing Hay and Straw without Spoilage

Start With Dry Bales, Not Best Hopes

Everything that happens once a bale is in the barn is damage limitation. The real work is done in the field, so get the moisture right before you stack. Hay is usually safe to store below about 14–18% moisture; straw sits comfortably around 18–20%. If you twist a handful of hay hard and it breaks with a crack rather than bending like a rope, it is close to ready. If the bale feels warm in the middle, smells of caramel or tobacco, or the strings are damp, it is still curing. Leave it out, turn it, and let it breathe a while longer.

A bale can feel perfectly dry on the outside and still be holding a wet core from an evening bale-up or a dull week with little sun. That core is what moulds, and what heats. Hay that gets hot enough can eventually smoulder and set a barn alight, so any stack that feels uncomfortably warm to the hand needs pulling apart and cooling, not covering up and hoping.

Get the Barn Ready Before the First Load Arrives

A wet winter will find every weakness in a building, so do the repairs in July rather than in the middle of a January downpour with a torch in your teeth. Clear the floor, sweep out old hay and dust, and get rid of last year's rotting bales — they are a reservoir of mould spores and a standing invitation to rats.

Check roof sheets, ridges and gutters for leaks and clear downpipes, so water runs away from the building rather than down the walls.
Open up ventilation: clear eaves gaps, blocked vents and doorways at both ends so air can move through the building.
Sweep out spilled grain, feed and chaff, which attract rodents long before the hay arrives.
Clear the floor of machinery, fertiliser bags and anything that stops you stacking neatly on pallets.

A dry, well-ventilated, sound-roofed barn is the best hay cover ever invented. Work on that first, and the rest becomes much easier.

Pallets, Air Gaps and Dry Stacking

Two rules matter more than any other. No bale touches the floor, and no bale touches the wall. Concrete sweats badly in a British winter, and damp creeps up from below. Pallets giving 100–150mm of clearance make an enormous difference to the bottom layer. If you are short of pallets, a sacrificial bottom course of bales you accept will spoil is better than nothing, but you will lose it.

Leave a clear 300mm gap between the stack and the walls, and don't fill up into the roof — keep at least 600mm of headspace so air can move over the top. Stack small square bales in neat blocks, alternating the direction of each layer so the stack locks together and the faces stay flat. Well-cured hay can be stacked fairly tightly; the movement you want is around the outside of the stack, not through the middle of it.

Round bales are best stored on their flat ends, in rows no more than two or three high, with the rows slightly apart so air can move between them. Never stack round bales against a wall or jammed under the eaves. Keep new hay and old hay separate, and always feed the oldest bales first.

Use Breathable Covers, Not Tarpaulins

The classic mistake is throwing a plastic tarpaulin over a stack. It looks tidy and does more harm than good: moisture condenses underneath, and you get a black band of mould along the top course and down the sides. Hay needs to breathe.

Use woven breathable hay covers, cotton sheets, or — on small stacks — a thick layer of loose straw laid over the top as a thatch. Whatever you use, let it overhang generously, tie it down well, and don't seal the sides to the ground. If the barn roof is sound and the stack sits clear of driving rain, an honest answer is that no cover is needed at all. In an open-fronted building, stack on the sheltered side and protect just the exposed face.

Keep Rodents and Birds Out

Rats and mice love a quiet stack. Look for droppings along the edges, gnawed strings and tunnels at the base. The most useful deterrent is simply being able to see: keep that 300mm margin around the stack clear so you notice activity early. Store feed in metal bins, sweep up spills, and set traps along the walls. Where bait is needed, use secure bait stations placed well away from livestock, dogs, cats and owls. A working cat or a busy terrier earns its keep in a barn.

Pigeons and sparrows foul the top of stacks, and their droppings carry disease and hold damp against the bales. Netting over open eaves or a solid roof solves most of it.

A Simple Winter Check Routine

Walk the stack weekly. Push a metal rod or probe deep into the hay, leave it twenty minutes, and pull it out — if it is too hot to hold comfortably, that hay is heating and needs pulling apart to cool. Smell matters too: sweet, tobacco-like hay is fine; musty, sour or sharply mouldy is not.

Watch for damp patches on walls, condensation on roof sheets, sagging covers and fresh rodent runs. Keep a torch and a notebook handy, rotate your stock oldest-first, and don't hoard more than a season's worth if space is tight. Do all of that, and the bales you put away in August will come out next March as sweet and clean as the day they went in.

Equipment

Essential Ventilation Tips for a Livestock Barn

A simple rennet set and gentle draining produce fresh cheese for salads, tarts or toast at home with ease.

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5 Comments

Robert Sonny says Jul 21, 2024 at 10:00am

I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
Reply
- John Abraham says Jul 21, 2024 at 10:00am
  
  I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
  Reply
  - Robert Sonnysays Jul 21, 2024 at 10:00am
    
    I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
    Reply
Robert Sonny says Jul 21, 2024 at 10:00am

I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
Reply

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