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About Fennel (Florence)

Florence or bulb fennel is grown for the swollen stem base, about the size of a tennis ball. It is an annual or biennial in cold climates — not a reliable perennial. Do not plant next to dill; they are close relatives and can cross. Leaf-and-seed fennel is a different crop — see Herbs.

When to Plant

Direct-sow after last frost, or start pots 4 weeks earlier. For a fall crop, sow 8–10 weeks before first frost. Heat plus long days makes it bolt without forming a bulb.

How to Plant

Sow ¼–½ inch deep (not 1 inch), 4 inches apart, thin to 10–12 inches. Rows 18 inches. Keep evenly moist — drought causes bolting. Hill soil around the bulb as it swells to keep it white and tender. Do not transplant if you can help it.

When to Harvest

Cut the bulb at soil level when it is 3–4 inches across, before it bolts. Leaves are edible too. Do not cut too much foliage if you still want the bulb to size up.