In the US "Corn Belt" it's planted in the spring, grows throughout the summer, and is harvested in mid-autumn.
it takes normally 4 months but now days due to high hybrids it takes approximately 3 months
soil nutrients
in the spring months which are March, April and May
onion is a cool season crop thus it should be planted starting October- January
At least 7,000 years ago. ( source: see Related Link [1] below )
autumn is the best time to sow grass seeds avoiding the heat of the summer
Yes
Yes, beans and corn are examples of annual plants. This means that in order to grow a crop of these types of vegetables new seeds must be planted every year.
in the spring
Only once, unless you grow it in certain regions of the world closer to the equator. Those areas can harvest two crops per year, but of course the corn has to be re-planted. This is not very common anywhere, since it is better for the soil to rotate to another crop after the corn.
The time of year a vegetable can be planted depends upon the hardiness zone you live in and the amount of time it takes for the vegetable being planted to mature. Your local extension agent can give you all the details for your area.
You should keep the soil it is planted in damp but not saturated at all times and yes it will need selective pruning as it grows each year to train it into the desired shape.
FALL