I have been looking into this, as I thought I didn’t get scapes because I was too far north. But it seems it must be the variety of garlic that is the factor, not so much the latitude.
I have found a garlic grower in Nairn, Scotland (farther north than Edinburgh, where I am). They are the Really Garlicky Company . Click on the “More about the products” button to have all your garlicky questions answered. Including all about scapes. It is the hard-necked garlic that grows scapes, not the usual soft-neck one.
Here is what they say:
“Technically, it is allium sativum ophioscorodon. Unlike the softneck garlic grown commercially, especially in Spain and China, this garlic subspecies produces a hard, woody flower stalk. The flower (topset or umbel) often contains bulbils. Many varieties develop partial or full coils in the stalks (scapes). We have to remove the scape in order to increase the size of the harvested bulbs.”
What a fascinating subject! This certainly is new for me!