Self-sowing works really well for cilantro and dill in my garden. Parsley sometimes self-sows. I can always count on lots of fresh cilantro and dill for May and June. For the July, August and Fall crops I sow the seed since these are hot months when sown seeds and young seedlings have to be watered frequently. Cilantro, dill, and parsley tolerate frosts and so it is possible to harvest fresh crops into December in my zone 5 garden.

Cheers!

Chervil2

LOL
I have cilantro, parsley, dill, tomatos, sunflowers, and swiss chard volunteering all over my garden. The hard parts are telling parsley from cilantro (easy once the plant has a little size, as my cilantro is VERY spicy) and deciding when enough is enough and weeding out the abundance.

My neighbor is supposed to come by tomorrow for some volunteer grape tomato plants.

I wouldn't worry about a special bed for self-seeding plants. I've found that the seeds will be carried far and wide by the wind in most cases! Parsley, for instance, at my place, has popped up about 10 metres from the original plant and travelled around a corner, and popped up in the cracks between concrete pavers! (Which proves that wind doesn't travel in straight lines.) The heavier seeds won't travel so far - but on the other hand, I've found nasturtium plants popping up a fair distance away from their mother plant, and they're quite large seeds!

Just let Nature get on with its job without expecting it to conform to your wishes and desires. It's quite a thrill discovering a plant in an unexpected place. I had quite a lot of lettuce plants grow in the pavers this year, and a couple of tomato plants (which I transplanted because they were right under my clothes line).

My suggestion is to plant two or three consecutive batches of seed over a period of a couple of months, and thereafter you should have a continuing supply - not necessarily where you want it!

Hmm. Thanks for your thoughtful replies. We'll see what happens!