Welsh onions (Allium fistulosum)

The small pot of somewhat neglected Welsh onions (Allium fistulosum) that I bought at a local nursery last summer continues to flourish. They're actually Asian bunching onions, but came to Wales and the UK long ago. They've become huge, and are now flowering, but continue to amaze me with how productive and delicious they are (not stringy or tough at all -- basically giant green onions). One of my favorite gardening podcasts, The Alternative Kitchen Garden had an interesting program about them.

What's not to like about perennial bunching onions?