Answer: You're likely to find two types of fennel at your garden center; Foeniculum vulgare or wild fennel (which is synonymous with F. officinale) and Foeniculum vulgare dulce, also known as sweet fennel. Both are perennial plants, often grown as annuals. Then there's Florence fennel, or finocchio, an annual with similar growing habits. What you're growing is probably the annual version and what you saw in the garden is probably the perennial type. Hope this clarifies things for you!
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