UC Master Gardeners, Santa Clara County, CA
University of California
UC Master Gardeners, Santa Clara County, CA

Fennel

Garden Help > Vegetables

The Basics

Florence (bulb) fennel, University of Maryland Extension
Florence (bulb) fennel, University of Maryland Extension
There are two types of fennel:

  • Florence fennel: grown primarily for the bulb-like base which is eaten as a vegetable. Leaves and seeds can also be harvested.
  • Common and bronze fennel: grown for the seeds, but not recommended due to invasiveness.

When to plant

  • Transplant or direct seed February–April (maybe May), September–October (maybe August).
  • If growing from seed for transplants, allow 4 weeks to be ready.

Harvest window

  • Harvest the bulb-like base when it is large and plump, 4–6" across, typically 60-90 days after transplanting. Cut just above the soil line.
  • Pollen can be collected from flower blooms by shaking flower heads into a plastic bag.
  • Pick leaves at any time during the growing season. Do not remove more than 1/3 of the foliage.
  • Harvest seeds when flower heads turns brown. Cut the seedheads and place in a paper bag in a cool, ventilated, location. The seeds will fall off when dry and can then be collected.

Care overview

  • Fennel is perennial, but is grown as an annual for harvesting as bulbs.
  • Fennel bulbs grow best in cool weather.
  • Space 8–12 inches apart.
  • Fennel will self-sow easily and can become weedy if not controlled. Common and bronze fennels are invasive pests in California.
  • Fennel is a host plant for swallowtail butterflies.

More links

Recommended Varieties for Santa Clara County*

Fennel Di Parma, OP Superior bulbing fennel, large and uniform, with great flavor. Flowers attract beneficial insects, and swallowtail butterflies will lay eggs on the feathery greens. 24–36" tall. Plant 10–12" apart.

* Many other varieties may also do well here in Santa Clara County. This list is based on UC Master Gardener trials, taste tests, and feedback from local growers.

 
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