When to plant
Bulb fennel: direct sow in spring for cool weather growing, or as a fall crop 8–10 weeks before frost. Bolts easily in heat — fall crops are usually more successful. Herb fennel: perennial in zones 4–9. Direct sow in spring after frost danger passes.
Soil & site
Well-drained, moderately fertile soil. pH 6.0–7.0. Work in compost. Keep away from most other vegetables — fennel releases chemicals that inhibit the growth of many plants. Especially harmful near tomatoes, peppers, and beans.
Feeding
Light to moderate feeder. Balanced fertilizer at planting, then side-dress with compost once or twice during the season. Avoid excessive nitrogen, which promotes leafy growth over bulb development.
Common problems
Aphids on fronds. Caterpillars of the black swallowtail butterfly eat the fronds. Powdery mildew. Bolts quickly in heat. Allelopathic to most garden plants — isolate fennel or grow it in a dedicated bed.
When to harvest
Bulb fennel: harvest when the bulb is 3–4 inches across and looks full and white-green. Harvest before it sends up a flower stalk, which makes the bulb tough and stringy. Herb fennel: harvest feathery fronds at any size; seeds when the umbel turns brown and seeds easily rub off.
How to harvest
Bulb fennel: cut at soil level, leaving the base — some varieties produce small second-growth shoots from the stub. Cut off tops, leaving 2–3 inches of stalk above the bulb. Herb fennel: snip fronds as needed. For seeds, cut umbels when 70% of seeds have turned brown-grey, and finish drying on paper.
Storage & use
Bulbs: wrap tightly and refrigerate for up to 2 weeks. Fronds: use fresh or store in a glass of water in the refrigerator. Seeds: dry completely and store in airtight jars for 2–3 years. All parts are edible with an anise-like flavor. Bulbs excellent roasted, raw in salads, or braised.
Useful for growing fennel
A few things that make this one easier — chosen for this plant, not a generic list.
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