Growing fennel (bulbing vs herb)

Fennel (*Foeniculum vulgare*) is sold in two fundamentally different forms at most garden centers, and confusing them leads to wasted effort. Herb fennel is grown for its feathery fronds and seeds. Bulbing fennel -- also called Florence fennel or finocchio -- is grown for the swollen stem base you.

Fennel (Foeniculum vulgare) is sold in two fundamentally different forms at most garden centers, and confusing them leads to wasted effort. Herb fennel is grown for its feathery fronds and seeds. Bulbing fennel — also called Florence fennel or finocchio — is grown for the swollen stem base you see in grocery stores. They are the same species but different varieties, and their culture differs in one key respect: bulbing fennel bolts aggressively in heat and day-length, while herb fennel tolerates more stress.

I don't grow fennel at my Long Island plot. The bulk of this guide is sourced from NC State, Cornell, and Penn State Extension publications.

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Identification: two types, same species

Per NC State Extension:

• ***Foeniculum vulgare (herb/sweet fennel):* Perennial in zones 4-9, grown for feathery bronze or green fronds and seeds. Reaches 3-5 feet tall. Does not form a swollen bulb base.
• ***Foeniculum vulgare var. azoricum (Florence/bulbing fennel):* Annual or biennial grown for the swollen stem base. Shorter plant, 18-24 inches, with thicker, flattened stem bases.

Bronze fennel ('Purpureum') is a cultivar of herb fennel prized for foliage color; it produces edible fronds but its seed yield is lower than the straight green species.