Galinas, I planted one ornamental (herb) fennel 6 years ago and even here in a mild zone7 it is far from being in the class of dandelion or horseradish. Here it seems to be a 2 or 3 year perrrenial tops it has naturalized some and there are a couple clumps around the yard, my guess is the chickens spread the seed and without cultivation and a bit of irrigation from me even those few clumps wouldn’t be there. The stems do well in soup perhaps not as good as the bulb but nice in minestrone. Fennel does have a deserved reputation as being attractive to all sorts of wasps (part of why I pamper it) if your friend is going to be squeamish about that I’d advise her not to plant it. If the wasps don’t put her off though and she likes it it doesn’t take much effort to encourage or eliminate so why not? Tom