How is hemp cultivated differently than marijuana

Other key differences between hemp and marijuana have to do with cultivation and harvesting. Male hemp plants flower much faster than females and do not produce nearly as much fiber. In stark contrast to marijuana fields, which seek to banish all males, most female hemp fields include sporadically placed males. 

Male hemp plants flower much faster than females and do not produce nearly as much fiber.
The male hemp plants release pollen female plants use to produce seeds that are either planted for future crops or sold as food. In marijuana fields, male plants are typically eliminated to ensure the maximum production of sinsemilla (seedless) flowers. 
While marijuana cultivation requires ample spacing to reduce the risk of mold or bacteria, hemp can be planted more densely. Most marijuana crops are planted with one plant per 4 square feet. Hemp plants that are grown for oil are planted at roughly 40 to 60 plants per 4 square feet. Those grown for fiber are even more densely planted at a rate of about 100 to 120 plants per 4 square feet. 
Hemp plants are almost always cultivated outdoors, as opposed to marijuana plants, which are often planted in greenhouses or indoor grow operations. Because hemp is susceptible to the same predators, diseases, and insects that attack marijuana, many cultivators employ a technique called crop rotation, in which alternating crops are planted in the same place, to avoid any buildup of these organisms and to allow nutrients to return to the soil. 
The specific order of crop rotation and types of crops being rotated with hemp will depend on the location of the farm. Hemp is also used as a rotational crop at farms where it is not the primary agricultural product. 

Frequently asked questions
Is hemp a drug?
Hemp itself is a plant. But CBD, which might be considered a drug, can be made from hemp. The US Food and Drug Administration has approved a CBD-based drug as a treatment for epilepsy. And many people worldwide use CBD products to treat a variety of ailments, though much more research needs to be done on CBD's efficacy against everything from cancer to acne. 
Is hemp legal in Australia?
Certain parts of the hemp plant are legal in Australia. The government has more information.
Is hemp legal in NZ?
The country has a licensing program for those interested in growing certain cultivars of hemp that contain less than 0.35% THC. 
What is hemp used for medically?
As stated above, CBD derived from hemp has a variety of uses. The most official is the FDA-approved drug to treat childhood epilepsy. Beyond that, more research needs to be done but scientists are looking at CBD to treat or ease symptoms of: