You're actually asking two different questions: How to grow tobacco, and how to cure and prep it.
Tobacco seed, in fact, is readily available. First decision is what kind do you want to grow? For instance, I grow ceremonial tobacco (Nicotiana rustica) quite often. It's almost maintainence free. It's also low growing and has small leaves, with yellow to yellow-green flowers (which is different than the white-to-pale-lavender and pink blossoms found on domestic tobacco).
On the other hand, Burley (Nicotaina tabacum), which is the most common smoking tobacco, requires a little more attention to detail. But it's still, at base, a weed, and will grow like one. Burley is a big plant, growing about 4 feet tall, with large, broad leaves. Connecticut Broadleaf (Nicotiana tabacum) has even bigger leaves.
Tobacco worms and hornworms can be a problem for tobacco growers. But both can be easily controlled in the home garden both by hand picking, and by the introduction of predatory wasps.
To maximize productivity you need to learn certain techniques, such as topping. I don't top my tobacco plants because I want them to produce seed. But the leaf size siffers thereby.
Then, once the plants are ready to harvest they have to be hung in a dry, but airy, location. You can tell tobacco barns from others because of the spaces between the wood planks to assure good air flow. Then, once cured, the leaves have to be stripped. To do that they have to be "in case," which depends on adding back enough humidity so the dry leaves become pliable. At that point, using a special knife made for the purpose, you cut away the center stems.
All that is for a simple air cure. But there are other approaches used to produce the leaf color desired. Cigar wrappers come in three shades; green, brown, and madura---which is almost black. And, in some places, notably Connecticut, they use a sugar cure, based on molassas, which is a whole nuther thing, used primarily to produce pipe tobacco.
Keep in mind, too, that we're only talking about American tobacco so far. There are others, and they often are used as part of blends.
Once you've grown and cured the bacca you then have to learn how to roll cigars. It's not a simple matter of stacking a few leaves and rolling them into a tube shape. Wrappers use different leaves than fillers, for instance, and the filler can be long-leaf (that's what's used in the best cigars) or various combinations of long-leaf and chopped. Rolling cigars is an art form that takes people years to learn.
There are people who grow tobacco in British Columbia, so I would guess it will grow by you.
Whew! Ain't ya glad you asked. :D
