Storing hay in a container on a Pine Belt farm without mold: vents, pallets, cured hay only
Yes, if the hay is cured and the box is vented: a 40ft container holds about 300 square bales stacked five high on pallets with a walkway, and keeps them out of the rain and off the ground. Green hay heats in any enclosure, and a sealed steel box makes it worse, so check the moisture before it goes in.
How much it holds
A 40ft standard box holds about 300 square bales stacked five high on pallets with a three-foot walkway, or about 200 bales plus a season of bagged shavings by the doors. That is a trailer-load and a half under steel instead of under a tarp.
Under a tarp, the top row goes to the weather and the bottom row goes to the ground. In a container on pallets, the whole stack stays usable. A 4x5 round bale clears the door on its side, and you can fit about 16 to 20 without a walkway, but most people use the bay for squares.
Cured hay only
Hay must be cured below 18 percent moisture before it goes into any enclosure, steel or wood. Green hay heats, and a sealed box traps that heat. A moisture probe is cheap, it is in the plan's cut list, and it is how you know.
The vents and pallets make the bay work. Air comes in low and goes out high, and the pallets let it move under the stack. Stack cut-side down, tight to the far end, with the newest hay at the back. Container condensation explains why the vents are not optional.
Mice and setting it
Steel keeps mice out of the walls; the doors are the gap. Put bait stations outside at the corners, never inside with feed, and sweep the sill when the stack goes in.
The truck needs about 100 feet of straight, firm run for a 40ft. Set the doors where the hay trailer backs up. For horse owners, the tack room and feed room use the same vent layout in a 20ft.
How many bales, by size
A 40ft standard holds about 300 two-string square bales five high with a walkway, and a 40ft high cube a few more. A 20ft holds a little under half of that. Compare the delivered price of the box to the hay you lose under a tarp in one season on the package page.
The layout, drawn to the box
This is sheet 2 of the free Hay & Shavings Bay plan set: the 40ft standard container drawn from real ISO dimensions, with every shelf, rack and opening placed. About 300 square bales five high on pallets with a 3 ft walkway, shavings by the doors, vents low-in high-out. Cured hay only.
All seven sheets: Cover and package price · Floor plan · Long-wall elevation: vents · Cross section: airflow and the stack · Site, pad and leveling · Parts, cut list and tools · Build order and disclaimer. You buy locally: sixteen pallets, a moisture probe, corner blocks — roughly $120–$220.
See the Hay & Shavings Bay package — container and kit, delivered price by ZIP →
Buying a container?
Longleaf sells used and one-trip 20ft and 40ft shipping containers, delivered by tilt-bed across the Pine Belt. Enter your ZIP for the delivered price — it comes straight from the supplier feed and already includes the haul. Locks, vents, shelving and lights are on the accessories page. We sell; we do not rent.
Keep reading
- Car, truck or boat storage in a shipping container: what clears the door — Will a car, pickup or boat fit in a shipping container? Door clearances for a 40ft high cube, what fits and what does not, and keeping the paint from sweating.
- A storm locker for a Gulfport, Biloxi or Ocean Springs business: generator, pumps and records — How a Coast restaurant, clinic or shop can use a 40ft container as a storm locker: generator by the doors, records up high, blocked, vented, loaded in June.
- One container for the whole Mississippi lease: four shelf bays, two locks, the split drawn before it comes — How a hunting club can share one 40ft container on a Mississippi lease: four numbered shelf bays, a pallet each, a shared hook wall, two padlocks, drawn first.
- A shipping container workshop in the Pine Belt: lights, shelving, power and the door question — How to set up a 40ft shipping container as a workshop in the Pine Belt: solar lights, no-drill shelving, one cord in for power, leveling, and the door choice.
- Storing a boat on its trailer in a 40ft container on the Gulf Coast: width, height, vent and moisture — Storing a boat in a 40ft shipping container on the Gulf Coast: door width and height limits, trailer and T-top clearance, salt air, moisture and storms.
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