Garlic scapes are one of the best heralds of summer. Up here in Maine, we plant garlic cloves in the fall, letting them grow some roots before the winter freeze. Then we weed and and feed them painstakingly in the spring. Garlic, like many other alliums, is day-length sensitive. It will only put on vegetative growth until the summer solstice. Then, it will start to form a bulb and mature. We try to get as much vegetative growth as we can, because a bigger plant essentially means bigger garlic!
Garlic scapes are the flower stalk of the garlic plant. Hardneck garlic varieties produce scapes, whereas softneck varieties have been bred to produce as few scapes as possible so the plant sends all its energy to the bulb. We grow mostly hardneck varieties (Phillips, German Extra Hardy, Georgian Fire, a strain of Music from NY and a strain of Music improved on in Bowdoinham) and one softneck (Inchelium Red).
When we pick garlic scapes, we not only get a delicious vegetable, we also cause the garlic plant to send its energy back into bulb forming. So by growing lots of hardnecks, we don't get as great a percentage of energy going to the bulb as with soft necks, but we'll take the garlic scapes instead. So will you, too, if you try this pesto!