Cumin seed will grow in the Northern Hemisphere clear into Norway. The plant will grow, but that does not mean you will have enough days of warmth to mature the fruit, or the cumin seed.
Where to Grow Cumin
Cumin is native the Mediterranean, supposedly originating from Egypt. So, if you are considering growing your own cumin, simply assess how closely your climate is to the countries bordering the Mediterranean Sea. The southwestern area of the United States is a good candidate for growing cumin.
How to Grow Cumin
Choosing Seed: Cumin seed maintains its viability for a good two years. So technically, if you have cumin you have used in cooking and have been satisfied with the quality, plant that.
If you are just tinkering and want a few plants or even a whole row of cumin in your garden, purchase a pack of seed from your favorite seed vendor like Nichols Garden Nursery.
But, if you have decided to go into large-scale production, shop around to get the best prices and best guarantees of germination. If you are organic, you will probably want to start with organic seed.
Planting Seed: Cumin is related to parsley. Both germinate best in cool spring temperatures although the mature plants will withstand really hot days.
You can directly sow into the soil. However, these seeds are slow to germinate and may be wildly overtaken by weeds before they get their heads out of the ground.
The better option is to start cumin in a cold frame or greenhouse situation in a potting soil mix that is weed-free. Be patient. These plants will do best if held in these situations until they are two to three inches tall and that could take eight weeks or more.
Harvesting Seed: Depending on your locale, you could be looking at a full year before you have cumin to harvest. Only experience will guide you on this kind of planning. Talk to someone in your area who has already grown cumin seed for the local wisdom on this topic.
Seeds develop on the top of large, round, flat flower clusters. Allow these stalks to remain on the plant until the plant is close to spent. This assures that the cumin seeds mature and store their flavor-filled oil.
Allow further dying after the harvest of the stalks. This should be done indoors to protect the cumin seeds from dew and rain. Spread the stalks loosely on a flat surface and cover with a thin cloth like muslin to keep dust and bugs to a minimum.
Check the stalks from time to time. When the cumin seeds readily part from the dried flower form is the best time to do the next step. Wearing thin cotton gloves, separate the seeds from the flower stalks. The gloves save wear and tear on your skin and help to keep your skin oils off the seeds.
If you plan to grow acres of cumin seed, you will need another method of removing the seed. It was common in days of yore to gather bundles of dried cumin stalks and beat them with a stick. That can still work today.
Spread out your cumin seed on a flat surface and pick out the debris including sticks, dried leaves, flower parts. Allow the cumin to dry like this for another couple of weeks. Nothing is more discouraging than packaging seeds prematurely only to discover a few months later that they had molded. This is a consequence of inadequate drying.