You can wait. Check on your variety, but most will hold in the ground for quite a while, so you can just harvest them as needed for cooking, then dig up the rest right before the ground freezes. You can always strip some of the outer leaves if they look bad.

Something I've found handy is to heavily mulch them when cold weather approaches. I was digging leeks into late winter, but by spring planting the few left were beginning to rot or develop seeds. Most were about an inch or larger diameter. Tasty!

Leeks are just a variety of flat onion chives. As with chives, you can cut them down to ground and they will grow back. You can also pull some up, at any stage. Smaller ones sare more tender than very big crocery store types that are very tough, like rubber.

Fantastic! I pulled 6 fatties and made a nice quantity of pureed soup with leftovers. Now I know I'm not rushed to get them out. Thanks.

cyrus - can you explain what you mean by onion chives, please? I googled but just get chives (Allium schoenoprasum). Leeks are Allium ameloprasum var. porum so are not the same thing at all. I am surprised you say leeks can be cut over and over since they make a single elongated bulb rather than a clump. How does it work? I've only ever come across leeks used as individual stems from pencil thickness to almost three inches diameter depending on variety and cultural technique.

I harvested all of my leeks over the weekend. I had a few that sent up flower stalks and once they do that, you have a hard "stem" up throught the middle of the leek that you will have to pull out before you use them. I washed, sliced and froze them for use in soups, etc.

I am no expert with leeks this was my first year. I planted American Flag. Started indoors in peat pots then hardened for a week. They were lanky so I trimmed them back to about 2 in. with shear when I planted them in garden. A couple of times over the summer they were stressed and I trimmed them back they responded well, and seemed to thicken with the trimming.Had leeks for dinner. Very good . Anybody else have info. on this I would like to know.I plan on having leeks again next year
Curt.