Most of us know this plant. Maize grows almost everywhere, and the range of products that come from it is remarkable. It is a cereal crop, widely consumed by people and by livestock alike, processed into countless industrial products, and increasingly used as a biofuel feedstock. That versatility is why corn is among the most valuable crops in the world.
This article covers growing maize, and it pays particular attention to the part most growing guides skip: harvesting it for silage. If your maize is destined for the feed bunk rather than the grain market, the harvest decision matters more than almost anything you do earlier in the season.
Types and Characteristics
Maize is a relatively forgiving crop to cultivate across seasons, growing in both wet and dry periods provided its water and mineral requirements are met. It is worth noting that it is a thirsty crop, so irrigation planning matters more than its reputation for easy growing suggests.
Botanically, maize is an annual grass with a non-woody stem and a fibrous root system comprising seminal roots, adventitious roots, and brace or support roots. Plant height varies considerably by variety. The leaves are long and narrow with parallel venation, and a slightly rough surface.
Kernel colour is the feature most people recognise, with white and yellow the most common, though red, pink, and black varieties exist. The husk covering those kernels is textured and fibrous, and in some regions it is used for decorative crafts.
Classification usually follows kernel type. The main groups are dent, flint, flour, sweet, and popcorn, and each suits a different purpose. Flour corn is the principal source of corn flour, sweet corn is grown for direct consumption, and dent corn is the workhorse used for grain and for silage.
Factors in Maize Growth Efficiency
Several factors influence how well a maize crop performs, covering seed selection, soil condition, grower knowledge, and general cultivation practice. Good growers keep pace with agricultural technology rather than farming the way they always have.
- Seed quality. Research your options before planting, including whether a hybrid with faster growth and stronger performance suits your conditions.
- Soil assessment. Soil condition is among the strongest determinants of how a maize crop develops.
- Realistic yield expectations. Understanding your crop type and seed variety lets you assess yield potential honestly rather than optimistically.
- Planting date. Often the single most important decision in the growing calendar.
- Crop rotation. Rotating crops improves the carrying capacity of the soil over time.
- Field observation. Regular scouting reveals soil condition, weed pressure, pests, disease, and overall crop performance while there is still time to respond.
- Irrigation. Adequate water is essential both to crop survival and to maximising production.
- Organic matter. Adding organic fertiliser maintains the soil condition that continuous production depends on.
- Weed management. Handle weeds as early and as often as possible, by manual or chemical means.
Growing Maize for Silage Is a Different Decision
Here is where a silage crop parts company with a grain crop.
If you are growing for grain, you wait for the crop to mature and dry down. If you are growing for silage, you are harvesting the whole plant while it still carries substantial moisture, because fermentation depends on it. Harvest too early and the crop is too wet; too late and it will not pack or ferment properly.
The target range is well established. Maize preserved between roughly 30 and 38 percent dry matter, which is 62 to 70 percent moisture, generally gives excellent fermentation and animal performance. Within that band, most guidance points to 65 to 70 percent moisture for bunker storage and bale silage, since that range packs well.
The stakes are higher than they appear. Harvesting too wet, above about 75 percent moisture, causes souring, seepage, and reduced intake because the silage becomes less palatable. Harvesting too dry brings mould, lower digestibility, and reduced protein and vitamins A and E. Whole-plant dry matter between 30 and 35 percent is where fibre and starch digestibility are at their best, and that matters commercially: a single percentage point increase in fibre digestibility has been associated with an increase of around half a pound of fat-corrected milk per cow.
The Milk Line Test Is Less Reliable Than You Think
Most growers were taught to judge silage harvest by the kernel milk line, breaking a cob and looking at how far the line has moved down the kernel. It is worth knowing that research does not support using it as the deciding factor.
The position of the kernel milk line is not a reliable indicator of harvest timing. In a Wisconsin study, 82 percent of the hybrids tested showed a poor relationship between milk line stage and whole-plant dry matter. Geographic location, planting date, hybrid choice, and weather all interfere with that relationship, and modern hybrids bred for stay-green characteristics have made it less dependable still. Kernels can be close to black layer while the plant as a whole is nowhere near dry enough to chop.
| Method | What It Is Good For |
|---|---|
| Kernel milk line | Deciding when to start sampling, not when to harvest |
| Days after silking | Rough planning, with silage maturity around 35 to 45 days after silking |
| Whole-plant moisture measurement | The only reliable way to decide the actual harvest date |
The practical method is straightforward. Use the milk line to tell you when to begin checking, then collect around five representative plants from across the field, avoiding edge rows, and measure whole-plant dry matter with a microwave, a drying oven, or a commercial forage moisture tester. Sample separate areas if parts of the field are drying at different rates. Combine that reading with a typical drydown rate of roughly 0.5 to 0.75 percentage points per day to predict when the crop will hit your target.
Corn silage is generally cut at a height of around 8 to 14 inches above ground level, which balances yield against quality.
From Field to Feed Bunk
Once the crop is at the right moisture, the operation becomes a race. Forage quality begins declining the moment it is cut, and for baled silage the wrapping needs to follow quickly, with research placing the quality threshold at roughly four hours after baling.
This is where the machinery decision connects back to the growing decision. A crop harvested at the right moment and then left unwrapped loses much of the advantage you spent a season building. Our guides to the baler wrapper range and to agricultural silage film cover the equipment and consumables for that stage, and our article on corn silage as feed explains how the finished product performs in a ration.
Maize is also one of the main feedstocks for biogas, where the same crop is ensiled for a digester rather than a herd. If that interests you, our guide to ensiling energy crops for biogas covers the differences.
To grow good maize in quantity, a great many things have to go right, and the machinery is one of them. Jummos manufactures agricultural machinery from Qingdao, China, with a one-year parts warranty and SGS audited supplier status, supplying farmers worldwide. Tell us your crop and your scale, and we will help you work out what fits.
Frequently Asked Questions
What moisture should maize be at for silage?
Between roughly 62 and 70 percent moisture, equivalent to 30 to 38 percent dry matter, gives good fermentation and animal performance. For bunker storage and baled silage, 65 to 70 percent moisture is commonly targeted because it packs well. Whole-plant dry matter between 30 and 35 percent is where fibre and starch digestibility are highest, which is where the feeding value comes from.
Is the kernel milk line a reliable way to time silage harvest?
No, and this surprises many growers. Research found that 82 percent of hybrids in one Wisconsin study showed a poor relationship between milk line position and whole-plant dry matter. Location, planting date, hybrid, and weather all distort the relationship, and modern stay-green hybrids have weakened it further. Use the milk line only as a signal to begin sampling, then measure whole-plant moisture directly to decide the harvest date.
What happens if maize is harvested too wet or too dry for silage?
Too wet, meaning above about 75 percent moisture, causes souring and seepage, and reduces intake because palatability suffers. Too dry allows mould to develop and lowers digestibility along with protein and vitamins A and E, and the crop also packs poorly, which leaves trapped air in the silage. Both errors cost feeding value, which is why measuring rather than estimating is worth the effort.
Is growing maize for silage different from growing it for grain?
The growing is broadly similar, but the harvest is entirely different. A grain crop is left to mature and dry down. A silage crop is cut as a whole plant while it still holds substantial moisture, because fermentation requires it. That means the harvest window for silage arrives earlier and is considerably narrower, and hitting it accurately matters more to the final feed value than most decisions taken earlier in the season.
Reviewed by Sue Su, Marketing Director of Jummos, on September 28, 2026. Harvest moisture and timing guidance was checked against current agronomy extension research to keep the information accurate for growers.