i think i already know the answer to this, but hey. So i'm stationed in Toronto, which is pretty cold. area... 7? b? i was at Sobeys(big GROCERY store) this evening digging through their "tropicals" (2-inch pots of random awesomes for 2.49$ woot) when i noticed that they're actually selling a few decent sized key lime shrubs for 50$. There were even a few blossoms on the trees. I'm so so so tempted to buy one, but i probably shouldn't, right? because Sobeys does groceries, not trees, right? like, they'd probably never ever blossom again? ...? yeah i know.
Even here in NW FL, key limes are a container citrus--they are one of the most sensitive to cold of all citrus. They are also the fastest to produce from seed--producing fruit in as little as 2-3 years. If you have key limes available in the store, you can just plant your own--they are true to type citrus (they will be identical to the parent tree).
Since you are in Toronto you need to check out Humber Nurseries. They are just above the airport off HWY 7 I believe. www.gardencentre.com They have the best citrus selection around and always have tons of key limes as well as oranges, grapefruit, lemons,etc.
