Product Field NotesCompanion Plants
Fennel Plants: Feathery Anise Herb for Cooks and Swallowtails
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Fennel is a tall, feathery herb with fine, needle-like, yellow-green leaves that smell of sweet anise and licorice when you brush them. In mid to late summer, it opens large, flat umbrellas of tiny yellow flowers. The leaves, flowers and seeds are all edible, so a single plant gives the kitchen something from spring to fall.
It is also a garden workhorse for wildlife. Fennel is a host plant for black swallowtail caterpillars and draws bees and other beneficial insects to its flowers.
Fennel at a glance
| Trait | What to expect |
|---|---|
| Botanical name | Foeniculum vulgare |
| Flowers | Tiny yellow flowers in large, flat umbels |
| Bloom | Starts mid-July, peaks mid-August |
| Size | 48 to 72 inches tall, 18 to 39 inches wide |
| Hardiness | USDA zones 4a to 9b; short-lived perennial, often grown as an annual |
| Scent and flavor | Sweet anise, licorice |
| Wildlife | Excellent for pollinators; swallowtail host; deer resistant |
| Water | Moderate |
Fennel and lavender in the same garden
Fennel likes the same full sun as lavender and tolerates heat well, but it is much taller and enjoys a bit more water. The best arrangement is fennel at the back of a sunny herb or pollinator bed, with lavender in front where it gets plenty of light and air. Its feathery green clouds make a soft backdrop for lavender's silver mounds and purple spikes.
Together they make a strong pollinator planting: lavender in early summer, fennel's yellow umbels from mid-July. Many gardeners give fennel its own spot at the edge of a bed, since it reseeds and its deep taproot makes established plants hard to move. Plan the layout in the Companion Plant Planner.
Growing tips
- Soil: well-drained. Stem and root rot can occur in poorly drained soil.
- Water: moderate. Very dry weather can push it to flower early.
- Bloom timing: it often does not bloom until its second year, though dry weather can trigger first-year flowers.
- Self-seeding: it is short-lived and often replaced by its own seedlings. Cut seed heads before they drop if you want to limit volunteers.
- Winter: listed hardy to zone 4a, so in zones 5 and 6 it can return in well-drained soil.
Harvesting for the kitchen
Snip the feathery leaves fresh and use them right away; their mild anise flavor is lovely with fish, salads and roasted vegetables. The yellow flowers make a pretty garnish. Leave a few heads standing if you want seed later in the season. Fennel and lavender also pair surprisingly well in baking and herb blends, so a little of each goes a long way.
Leave some for the caterpillars
If you see striped green, black and yellow caterpillars on your fennel, those are likely black swallowtails. Planting enough to share means you get butterflies later in summer, and the plant usually bounces back.
Choosing a size
Fennel is offered as a 3-inch plug, a 4-inch pot and a 1-gallon pot. Plugs are economical for planting several, while the gallon size gives a head start on harvests. See the product page for current sizes and availability.
Frequently asked questions
When do I collect fennel seed?
Let the seed heads turn brown on the plant first, then cut them into a paper bag to finish drying.
Will it come back next year?
It can, in well-drained soil within its zone range, but it is short-lived. Its own seedlings usually carry it on.
Do deer eat fennel?
Deer tend to leave it alone.
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