Saffron Crocus can be grown in areas with colder winters than Zone 6, but the corms must be lifted and brought indoors for the winter. After the first few frosts, but before the ground has frozen solid, carefully dig out the corms, place them in a wooden crate or plastic tub, and completely cover with dry peat moss or sand.
Store in a cool (40-50°F), dry place. Plant them out again in the spring after all danger of frost has passed, but doesn’t water until you see new growth in early autumn.
Another way of growing Saffron Crocus in cold-winter areas like Iran is to plant the corms 2 in. deep in clay or plastic pots filled with a well-drained soil mix, and then set the pots directly in the ground, with the rims about 2 inches below the soil surface, so the pots don't show. After the plants die back in the fall, move the pots into the basement and store them dry for the winter. Set the pots back out the following spring.
Again, marking the pots' location so you don't accidentally dig into them is probably a good idea.

Three stigmas are borne in the center of each purple, cup-shaped bloom. The best time to harvest the stigmas is mid-morning on a sunny day when the flowers have fully opened and are still fresh. Carefully pluck the stigmas from the flowers with your fingers, and then dry them in a warm place to preserve them for cooking.
Store in a closed container. To use saffron, steep the threads in hot liquid (water, broth, or milk, depending on the recipe) for about 20 minutes. Add both the threads and the steeping liquid early in the cooking or baking process, and the threads will continue to release their color and flavor.

Saffron spice is the three red stigma of the purple Crocus sativa flower. It is an extremely aromatic spice and although it is red, it is not at all hot. It has a complex flavor and aroma and is described as having a slightly bitter honey like taste. Saffron is the most expensive spice in the world. Though, because the intense flavor, only a small amount of saffron is needed when cooking.
Depending on the size of the stigma (3/flower), it can take between 70,000 to 200,000 flowers to produce 1 kg of the spice. The cultivation, harvesting and processing of saffron is carried out completely be hand. Adding to the cost of the spice.
Saffron is used to season sweat and savory foods, such as rice, meat and fish dishes. Also cheese, both soft and hard. Saffron has also been an ingredient in ice cream, cakes, and liqueurs.
Close to 170 to 200 tons of saffron are produced each year. The bulk of which is produced by Iran, Greece and Kashmir, followed by Spain.