Are you planning on eating the fennel bases? If not, why are you growing them? (just curious) If you leave the "bulbs" they will re-sprout new growth.

Bronze Fennel is the type where you can the soft, dark, strands.

Why would you can it? I've used the leaves for flavoring cooked food, and even tried drying it.

Now, I've used Dill leaves, as well as the heads (umbels), in making dill pickles, but never fennel.

Fennel comes in two 'versions'*, both botanically the same plant. One has been bred to produce bulbous stem bases for use as a vegetable. This is also known as Florence fennel. The fennel the poster has is the other type bred soley for use as a herb. This type comes in green or bronze colouring. The seeds, leaves and stems are used. You can treat it as any other perennial. Cut it down when it looks messy and it will keep coming up every year if you live in the right climate. You have definitely not ruined it, although I tend to leave the stems during the winter to provide refuge for beneficials, especially ladybirds, in the hollow stems and to look architectural. I cut them back in spring. As for the 'can', I took that as a typo with the missing word being 'use'.

* There are some other fennels but these two are the main ones grown in gardens.

Thanks for the enlightenment; I didn't know about the stalk fennel.

Fennel (the non-bulbous one) is very drought tolerant. It also doesn't mind a bit of salt. I should think it would do well in Ca. Maybe you could try it? It's really trouble free to grow. It grows wild in the UK in seaside locations.