I have done this before, and with small leeks you can regrow them twice. They are also quite winter hardy. You could probably plant it outside and it would grow.

In my experience, leeks are very late to go to seed. Those that come through winter don't bloom until midsummer.

For a close-to-perpetual supply of green onion tops for clipping, you should look at top-setting or Egyptian onions. Lots of green onions for very little effort.

My reply never made it.

I actually have a strain of walking onion, but have spent most of my life an onionphobe, refusing to eat them unless they were pureed and well cooked. Leeks are wonderful.

Can anyone comment on the difference between leeks and walking onions (besides one having very hollow leaves)?

The two ends rooted well and have sent up 5 inch tall, dark green shoots. I'll transplant them before the frosts begin.