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Harvest, Storage & Post-Harvest TimingDrying Calendar for Grain
Grain keeps well when it is dry and cool, and it spoils when it is not. A drying calendar is a set of checkpoints tied to moisture and weather, not a list of dates.
Key points
- Plan around moisture targets for your crop and storage length, from your state extension guide.
- Cool the grain as soon as the weather allows after fill.
- Check the bin on a steady schedule and after every sharp weather change.
- Never enter a bin with crusted or bridged grain.
When should grain be dried?
Drying is driven by moisture, not by the date on the wall. Grain harvested wetter than the level your extension office recommends for your planned storage length needs to come down before it goes into the bin. The longer you plan to hold it, and the warmer the months it will sit through, the drier it needs to be.
Start your calendar at harvest and work forward. Write down the date each field was cut, the moisture reading from a meter you have checked against the elevator's, and where each load went.
How do you choose a target moisture for storage?
Targets differ by crop and by how long you will store. Corn headed for sale in a few weeks can usually be held wetter than corn going into spring or summer storage. Soybeans and small grains have their own targets. Check your state extension guide for the numbers that fit your crop and storage plan, because quoting one figure for everyone would be wrong.
Use the same rule for every bin: dry to the level for the latest date you might still be holding that grain, not the date you hope to sell it.
What does a drying and storage calendar look like through the year?
Think in four stretches. At harvest you are measuring moisture, drying and cooling. In the first cold weeks you are cooling the bin down and checking for warm spots. Through winter you are watching for crusting, condensation and odors. When spring warms up you are deciding whether to sell, move or re-dry before the grain heats again.
For example, if your bin is filled in October and cold weather usually settles in by December where you farm, the weeks between fill and cold are the highest-risk window for wetter grain, so those are the weeks to check most often.
- Harvest: sample from several spots in the load, not just the top
- First cold stretch: run fans to bring the grain mass to the outdoor temperature
- Mid-winter: probe the bin on a regular schedule and note any change
- Spring warm-up: decide before the bin warms, not after
How do bin type and fans change the schedule?
A bin with a full aeration system and temperature cables gives you early warning and a way to act. A bin with a single fan or none gives you less room for error and should be filled with drier grain. Natural-air drying depends heavily on the weather during the drying period, so fall humidity and temperature matter as much as the fan.
Learn how many days your system needs to move a drying front through the bin, and do not add more grain on top of a bin that is still working. Your extension grain storage specialist can help you match airflow to depth and moisture.
What mistakes cause stored grain to go out of condition?
Most problems start with mixing wet and dry loads, filling a bin with a peak of fines in the center, or leaving the grain warm after fill. Moisture then moves toward the cool surface, condenses, and starts a crust that hides the trouble underneath.
Another common slip is skipping the first check after a weather swing. A warm spell in late winter can restart insect and mold activity in a bin that looked fine a month earlier.
- Mixing grain of different moistures in one bin
- Not cleaning out old grain and fines before harvest
- Failing to level or core the bin after filling
- Ignoring odor, a crust or a warm spot
What should you do when you find a problem?
If the grain is warming, has a musty smell or a crust, run aeration under guidance, move some out if you can, and call your extension office or elevator before the problem spreads. Do not enter a bin with a crust or bridged grain. Entrapment and gas hazards are real, and farm safety groups and extension both have bin entry guidance.
Record what you found and what you did. That log is the start of next year's calendar.
How do you keep records that make next year easier?
Keep a one-page log per bin: fill dates, moisture at fill, fan hours, temperature readings and any problems. After two or three seasons you will see which fields run wetter, which bins hold heat, and how much drying time a typical fall actually gives you.
Share the log with your adviser or elevator manager when you ask questions. Specific notes get specific answers, and they help when you talk to an insurance agent or lender about stored grain.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.