Garlic scapes are the "flower" stalks of hardneck garlic plants. These twisting and twirling stems shoot up from the center of the garlic plant's leaves and signal that the garlic is 3-6 weeks away from being ready to harvest.
While the scapes do not need to be cut off the plants, some people believe the plants energy will be diverted from forming plump bulbs if the flower was allowed to grow. However, last year I left the scapes on a couple of the garlic plants and did not notice any significant difference between the size or weight of the garlic. So, I do not think it hurts the size of the bulb to the keep the garlic scape on the plant...but why waste such a tasty treat.
I first noticed the garlic scapes forming about 3 weeks ago. Since it is best to harvest young and tender garlic scapes, I have been keeping a watchful eye on the stalks as they twisted and turned. If I harvest the garlic scapes too early, the scape will continue to grow, making it difficult to remove the nub of new growth. Too late and the scape would be too fiborous to eat. And, you will want to eat them! Garlic scapes have the texture of fresh green beans and taste like mild garlic. They are excellent in salads, stir-fries, and pestos!
To remove the scape, I use a handheld plant pruner. I carefully snip off the garlic scape close to the base of the top leaves. A little bit of moisture will ooze from the cut ends but a seal will form in about 1 day.
After cutting the garlic scapes from the plants, I give the plants their final drink of supplemental water. Garlic needs just enough water to help form a large bulb. However, too much water may prevent the papery wrappers, required for long-term storage, from forming over the next couple of weeks. The worst thing that can happen is the garlic bulbs are exposed to too much water and get moldy. Mother nature, please cooperate!
The stress of withholding moisture will signal the garlic to fatten up. When the bottom 2-3 leaves of the garlic plant turn brown, it is time to feel the bulbs to see if they are ready to harvest. To do this, I dig down 4-5 inches below the surface of the soil (about 3 inches away from the plant's stalk) and feel the garlic bulb. If I can feel a nice plump bulb, I grab my spading fork and start harvesting garlic. If not, I wait a few more days and check again.
In general, garlic planted in October/November of the previous year will be ready to harvest in mid-June to late July.