Most of a wheat crop's yield is decided in its first few weeks, long before you see a single ear. The date you sow, how much seed goes in, how deep it sits and how evenly it comes up set a ceiling for everything that follows.
Fertiliser, irrigation and spraying can help the crop reach that ceiling. They cannot raise it.
In this guide we go step by step.
Choosing the sowing window for where you farm, preparing the seedbed, picking and testing seed, working out the seed rate with one simple formula, getting depth and spacing right, feeding and watering at sowing, starting weed control, and checking the stand three weeks later. The advice is general and global.
Your local variety list and extension service always have the final word.
Start with timing.
Wheat comes in two broad habits.
Winter wheat needs a spell of cold, called vernalisation, before it will flower, so it is sown in autumn and grows through the winter.
Spring wheat needs no cold spell. In cold places, such as the Canadian prairies, the northern Great Plains or Siberia, it is sown in spring, as soon as the soil can be worked. In warmer places, such as South Asia, the Nile valley, northern Mexico or much of Australia, spring-habit wheat is sown in autumn or early winter and grows through the cool season.
So the calendar depends on where you are.
Winter wheat in Europe and North America usually goes in from September to October. On the plains of South Asia, the best window usually runs from the end of October to the middle of November.
In Australia, sowing runs from about April to June, and in Argentina from about May to July.
Why does the window matter so much? Because the crop must fill its grain before the heat arrives.
When daytime temperatures during grain filling climb above about thirty degrees Celsius, the grain fills for fewer days and stays smaller. In warm wheat regions, every day of delay after the best window commonly costs around one percent of yield.
Sowing too early has risks of its own. In warm soil an early crop can grow too lush, invite pests and disease, and flower before the risk of frost has passed.
Next, the seedbed. Wheat wants a bed that is firm below, with fine, moist soil at seed depth and a few small clods on top.
Fluffy, over-worked soil dries out quickly and lets the seed sink too deep.
Big clods leave air gaps, so the seed does not touch moist soil and the crop comes up unevenly.
You do not always need to plough. In many regions, from the Great Plains to Australia and the rice-wheat systems of South Asia, wheat is sown straight into the last crop's residue with a zero-till drill. This saves fuel and time, holds moisture, and lets you sow earlier. In rice-wheat areas it also replaces burning the straw, which harms the soil and the air. If you sow into residue, make sure the drill cuts through the straw and places the seed in soil, not in a mat of stubble.
Sow into moisture.
A wheat seed has to soak up roughly a third to a half of its own weight in water before it can germinate. In irrigated systems, a pre-sowing irrigation brings the soil to the right moisture.
Then sow as soon as you can walk on the field and the soil crumbles in your hand without sticking.
Now the seed.
Choose a variety bred for your region and your sowing date.
Varieties differ in how fast they develop, how well they handle heat, and which rust races they resist.
Rust races change over time, so use the current recommended list, not last decade's.
Use certified seed where you can. If you save your own, clean it, grade out small and broken grain, and store it dry.
Before you sow, test germination.
Count out one hundred seeds, lay them on damp paper towel, roll it up, keep it moist at room temperature, and count the healthy seedlings after about a week. Do this three or four times and take the average.
That number goes straight into the seed rate.
Seed treatment protects the crop from diseases that start in or on the seed, such as loose smut, common bunt and some seedling blights.
Fungicide seed treatments are grouped by their FRAC code,
for example group three, the triazoles, or group seven, the carboxamides.
Choose a product registered for wheat in your country, follow the label dose, and wear gloves.
Treated seed must never be eaten or fed to animals.
How much seed should you sow?
Do not think in kilograms first.
Think in plants.
Decide how many plants you want on each square metre, and then let seed size and germination decide the kilograms.
Targets vary with the system.
Many irrigated and high-rainfall crops aim for roughly two hundred to three hundred and fifty plants per square metre. Dry, low-rainfall crops often aim for far fewer, around one hundred to one hundred and fifty, because each plant needs more water.
Late sowing usually needs a higher target, because late plants make fewer tillers.
Here is the formula.
Seed rate, in kilograms per hectare, equals target plants per square metre, times thousand grain weight in grams, divided by expected establishment in percent.
Establishment is the share of sown seeds that become plants: your germination result, reduced for losses in the field. With good seed, a good drill and a good seedbed it might be eighty to ninety percent.
In poor conditions it can fall well below seventy.
An example.
You want two hundred and fifty plants per square metre. Your seed weighs forty grams per thousand grains.
You expect eighty-five percent establishment.
Two hundred and fifty times forty is ten thousand.
Ten thousand divided by eighty-five is about one hundred and eighteen kilograms per hectare. If your seed is bigger, say fifty grams per thousand, the same stand needs about one hundred and forty-seven kilograms.
That is why two farmers with the same target can need very different seed rates.
Depth is where many crops go wrong.
For most wheat, place the seed three to five centimetres deep, into moist soil.
Modern semi-dwarf varieties carry dwarfing genes that also shorten the
coleoptile, the protective sheath that pushes the first leaf up through the soil.
Sown too deep, the coleoptile runs out of length before it reaches the surface. The seedling then stays underground, emerges late, or comes up weak.
Only go deeper to reach moisture if your variety is known to have a long coleoptile.
Rows are commonly fifteen to twenty-five centimetres apart.
Narrower rows close the canopy sooner and compete better with weeds.
Wider rows let zero-till drills pass through heavy residue. Whatever you choose, sow in rows with a drill if you possibly can. Broadcasting seed by hand or with a spinner leaves it at random depths, so it needs more seed and still gives a patchier stand. If you must broadcast, cover the seed with a light harrow straight away.
Feed the crop at sowing, guided by a soil test.
Phosphorus matters most at the start, because it barely moves in soil and young roots need it close by.
Place it in a band near the seed with the drill, rather than spreading it on the surface.
Potassium and zinc go in at sowing too, where the soil test shows they are short.
Nitrogen is different.
Give only part of it at sowing, often a third to a half of the total, and the rest later, at tillering and, in high-yielding crops, again as the stem starts to lengthen, when the crop can actually use it. Keep urea, and high rates of any fertiliser, out of direct contact with the seed. The salt and ammonia can burn the germinating seedling.
In irrigated wheat, the first watering after sowing usually falls at crown root initiation, about three weeks after sowing, when the permanent roots begin to grow from the crown. Missing water at this stage is one of the costliest mistakes in irrigated wheat.
The weed fight begins on sowing day too. Grass weeds such as littleseed canarygrass in South Asia, blackgrass in Europe and annual ryegrass in Australia have evolved resistance to many herbicides.
Use a stale seedbed where you can: let the first flush of weeds come up after irrigation or rain, kill it, and then sow. If you use a pre-emergence herbicide, apply it within the window on the label,
usually straight after sowing and before the crop emerges.
Choose it by its HRAC group, the herbicide mode-of-action code, and rotate groups from season to season so that resistance builds more slowly. We will cover weed control in wheat, group by group, in a separate video.
About two to three weeks after sowing, walk the field and count. Lay a one-metre stick along a row, count the plants, and repeat in at least ten places across the field. Then divide the average by your row spacing in metres. Fifty plants per metre of row, with rows twenty centimetres apart, means two hundred and fifty plants per square metre. Right on target.
If the count is far below target, find out why before next season.
Seed too deep, a dry seedbed, a crust after rain, soil insects, or birds.
Write down the date, variety, seed rate, depth and plant count every year. After a few seasons, those notes will tell you more about your own fields than any general guide.
To recap.
Sow in your region's window, so grain filling beats the heat. Prepare a firm, moist seedbed, or drill straight into residue. Use tested, treated seed of a recommended variety. Work out the seed rate from plants per square metre, grain weight and establishment.
Sow three to five centimetres deep, in rows.
Band the phosphorus, split the nitrogen, and do not miss the first irrigation.
Start weed control at sowing. And count your plants three weeks later.
For the full wheat guide, from sowing to harvest, visit laisha.ai. Thank you for watching, and may your stand come up even.
