How do you grow fennel microgreens? Sow fennel seed on a moist mix or grow mat, press it in, and keep it covered near 75°F (24°C) until it sprouts. Then grow it under light with bottom watering for 16–25 days, and cut at 1/2–2 inches (1–5 cm). Johnny’s Selected Seeds says a few extra days after the first true leaf deepens the flavor.
Key takeaway: Fennel microgreens are a slower, aromatic herb micro with feathery leaves and a sweet anise note. Johnny’s Selected Seeds lists green fennel (Foeniculum vulgare) microgreens in its slow-growing 16–25 day group, and NC State Extension describes fennel leaves as having a sweet, mildly anise or licorice flavor.
| Factor | Guideline | Source |
|---|---|---|
| Days to harvest for fennel microgreens | 16–25 days | Johnny’s Selected Seeds |
| Seed count | About 112,600 seeds per lb | Johnny’s Selected Seeds |
| Germination temperature | 75°F (24°C), then 60°F (16°C) root zone | Johnny’s Selected Seeds |
| Air temperature | 65–75°F (18–24°C) | Johnny’s Selected Seeds |
| Harvest height | 1/2–2 in (1–5 cm) | Johnny’s Selected Seeds |
| Flavor | Sweet, mild anise; stronger with age | Johnny’s Selected Seeds |
What Do Fennel Microgreens Taste Like?
Sweet and lightly anise-flavored. Johnny’s describes green fennel microgreens as finely textured, light-green leaves that add sweet fennel flavor to desserts and fish, and notes that fennel at the micro stage can be quite mild. University of Wisconsin–Madison Extension explains that fennel, anise and star anise all contain the aromatic compound anethole, which gives them a similar taste.
- Green fennel: feathery light green leaves, mild fennel.
- Bronze fennel: feathery bronze leaves, also mild.
- Use: fish, salads, desserts and garnishes.
Why Do Fennel Microgreens Take Longer?
Fennel is an herb with a slower crop time. Johnny’s places fennel in its slow group, which it says is usually ready in 16 to 25 days, compared with 10 to 15 days for fast varieties such as many brassicas. Johnny’s also says fennel flavor develops and intensifies as plants mature, so adding a few days after the first true leaf appears can strengthen it.
If you want a faster anise-like micro, compare our dill microgreens guide.
How Do You Grow Fennel Microgreens Step by Step?
Follow Johnny’s general microgreen method. Broadcast seed on moist potting mix or another soilless medium in shallow trays, press it firmly into the surface, and cover lightly with mix, vermiculite or a humidity dome. Johnny’s chart states that all of its microgreens are suitable for hydroponic growing, so a grow mat with bottom watering also works.
- Fill a shallow tray with moist mix or a grow mat.
- Sow untreated fennel seed evenly and fairly densely.
- Press seed into the surface for good contact.
- Cover with a thin layer of mix or a blackout lid.
- Keep the root zone near 75°F (24°C) until sprouting.
- Uncover and move under a grow light.
- Bottom water and keep moisture even for 2–3 weeks.
How Much Fennel Seed Per Tray?
Johnny’s does not publish a yield-trial rate for green fennel, but it lists about 112,600 seeds per pound. Penn State Extension recommends roughly 2 seeds per square inch (1 per cm²) for larger seeds up to 12 per square inch (6 per cm²) for small seeds. Start in the middle of that range and adjust after your first tray.
What Light and Temperature Do Fennel Microgreens Need?
Johnny’s recommends 75°F (24°C) soil until germination, then 60°F (16°C), with air at 65–75°F (18–24°C); temperatures above 75°F (24°C) increase disease and inhibit germination. Oregon State University Extension suggests covering trays for about three to four days and then using a lamp about 3 inches (7.5 cm) above the plants for about 15 hours a day.
- Blackout: until most seeds have sprouted.
- Light: about 15 hours a day; dim light causes leaning, leggy growth.
- Airflow: fans reduce damping-off over the longer crop time.
See our microgreens light requirements guide for setups.
How Do You Water and Feed Fennel Microgreens?
Bottom water and keep moisture even. Johnny’s recommends bottom watering or misting so mix does not splash onto the seedlings and says never to let the medium dry out. It adds that a dilute fertilizer solution is appropriate for media with no nutrients and for slow-growing species that might exhaust fertility before harvest, which can apply to fennel.
When Do You Harvest Fennel Microgreens?
Usually 16 to 25 days after sowing. Johnny’s says to harvest once cotyledons are fully developed or the first true leaves emerge, typically at 1/2–2 inches (1–5 cm) tall, using scissors or a sharp knife. For stronger fennel flavor, wait a few extra days after the first feathery true leaf appears, as Johnny’s suggests.
Our how long do microgreens last guide covers storage after cutting.
Are Fennel Microgreens Safe to Eat?
Yes; fennel leaves are edible. University of Wisconsin–Madison Extension says both fennel leaves and stems are edible with a light anise flavor, but notes the plant sap can irritate the skin of sensitive people, especially in sunlight. Johnny’s says microgreens must be washed before serving, and Penn State Extension recommends untreated seed marketed for sprouts and microgreens.
Can You Grow Fennel Microgreens Into Full Plants?
You can, but grow mature plants carefully. Wisconsin Extension says fennel readily reseeds in mild climates and may become invasive, and NC State Extension notes it is a larval host for certain swallowtail butterflies. For adult plants indoors, see our guide on how to grow fennel hydroponically.
Which Fennel Is Best for Fennel Microgreens?
Green or bronze common fennel. Johnny’s comparison chart lists green fennel with feathery light green leaves and bronze fennel with feathery bronze leaves, both with a mild fennel taste, so bronze adds color to mixes. Wisconsin Extension notes that Florence fennel (var. azoricum) is the type grown for its swollen bulb, which matters only if you grow plants to maturity.
FAQ About Fennel Microgreens
How long do fennel microgreens take?
About 16–25 days, per Johnny’s.
What do fennel microgreens taste like?
Sweet and mildly anise-like.
How do I make fennel microgreens taste stronger?
Grow a few days past the first true leaf.
Can fennel microgreens grow hydroponically?
Yes, on mats with bottom watering.
Are bronze and green fennel both good micros?
Yes; Johnny’s lists both.
How tall should they be at harvest?
About 1/2–2 inches (1–5 cm).
Sources
- Johnny’s Selected Seeds — Fennel, Green Organic Microgreen Seed
- NC State Extension — Foeniculum vulgare
- University of Wisconsin–Madison Extension — Fennel
- Penn State Extension — The ABCs of Microgreens
- Oregon State University Extension — Microgreens
- Johnny’s Selected Seeds — Microgreens Comparison Chart
- Photo credits (Wikimedia Commons, edited with titles): -2020-06-29 Fennel seedlings (Foeniculum), Trimingham by Kolforn (Kolforn) I’d appreciate if you could mail me (Kolforn@gmail.com) if you (CC BY-SA 4.0); Fenouil en jardinière D170309 a by Tangopaso (Public domain); Starr-110515-6518-Foeniculum vulgare-leaves-Science City-Maui (24976901742) by Forest and Kim Starr (CC BY 3.0 us)