TFO is right. They bolt even in shade. In a mediterranean climate, you would plant in August for harvest in February, but lacking that, direct seeding In June or July is best in the midwest. They can go after lettuce, for example.

Hi there, I'm interested in Bronze Fennel since I won't grow milkweed and fennel is safe and edible, let me know what we can trade, thanks. Love butterflies. Bea

I grow both the bronze and the Florence. I also grow Rue which they consume just as readily as the fennel, and Zizia aptera as a back up, which they sometimes lay eggs on and eat when the fennels in the front yard are chewed down. Differentiating between the "varieties" of fennel is somewhat confusing because there is a lot of conflicting information floating around on the web. However, Foeniculum vulgare var. dulce is the most commonly grown fennel, and is used for its seeds, foliage, and the stalks (similar in texture and eaten like celery). It is perennial in temperate climates, like Oklahoma. The Bronze is a close relative, F. vulgare var. purpurescens, used in the same fashion as the dulce. F. vulgare var. azoricum is used for seeds, foliage, and the bulbous base is used as a vegetable (you've probably seen in the produce section of the supermarket). Calling them Florence fennel leads to more confusion cuz I find both referred to as Florence, depending on the writer. The butterflies don't care which one you use. thank goodness! The azoricum is less hardy than the dulce, but both are short-lived perennials IMHO, and are borderline hardy in Oklahoma, where winter extremes are variable from year to year. The good thing is that they do self-sow readily. That said, one year I had to remove the flowers due to a heavy wasp invasion. They loved the fennel flowers and the baby BSTs. I personally like the bulb fennel the best because produces more lush foliage which in a good winter stays green and full. I just don't use the bulbs. It has lasted 4 or 5 years max for me. The Bronze seems more prone to winter die back than the bulb, and I have to generally buy new plants. So, there you have my explanation and interpretation on the performance of fennel in my zone 7a garden. Susan

Aargh. Another myth gets retold. This is my pet herb myth of the moment since dill is herb of the year for 2010. Dill and fennel DO NOT cross pollinate. They aren't even that closely related (at the family level only). They are no more likely to cross with each other than with other members of the Apiacea (Umbelliferae) family such as parsley or anise. The passing morphological similarities don't make them more likely to cross. Cross pollination between genera is extremely rare. I know some botanists that would be extremely excited to be able to catalog a Foeniculum (fennel) and Anethum (dill) hybrid as there are no examples in any of the literature. Even if they did cross and did produce viable seed, it would be the offspring that would be affected, not the original plants. Fennel (Foeniculum vulgare) is on the invasives list mostly because it is not native and out competes some native plants in certain areas. It doesn't necessarily have anything to do with its performance in the garden, which in most cases is also full of non-native plants. But it can reseed with abandon and become "invasive" in that sense as well. Do a google search for "invasive plants fennel". Certain plant produced chemicals have been shown to be allelopathic but just because a plant produces that chemical doesn't mean that the plant itself is allelopathic. It may not produce enough or the chemical may not even leave the plant. This is a relatively new science that is not yet fully understood. Many of the studies that have "proven" allelopathy have been seriously flawed. Trying to create an experiment outside the laboratory that controls for all the other possible explanations for nearby plants being affected has proven to be very difficult. F. DeBaggio