Unlike the well-known Florence fennel, which is harvested for its bulbous root, Bronze fennel is grown for its leaves and seeds with a flavor akin to anise. The feathery foliage takes on a reddish/bronze hue, grows 3–6′ tall, and is often used as a garnish or herb. Seeds can be used as a spice, made into tea, or chewed to freshen breath. This variety of fennel is a fast grower and is actually considered an invasive weed in many parts of the US. For this reason, we recommend planting your Bronze fennel in a pot to help keep your plant contained.
Seed Depth: 1/8–1/4″
Space Between Plants: 6–12″
Space Between Rows: 10″
Germination Soil Temperature: 45–90°F, while 70°F is ideal.
Days for Germination: 10–14
Sow Indoors: Sow inside 4–6 weeks before average last frost.
Sow Outdoors: 2–3 weeks before the average last frost date. For a continuous harvest, sow every 3 weeks until midsummer.
Vegetative: Fennel will grow well from seed but can also be propagated using root cuttings or crown division.
As fennel hails from the Mediterranean, it’ll do best in climates that mimic this region. Mild temperatures around 60–70°F and good air circulation will maximize your crops productivity, although it’ll still grow in temperatures that surpass this range—up to 90°F—as long as it’s provided with shade and adequate irrigation. Fennel can be grown as an annual in climates below USDA Zone 6 and, in warmer regions, can be grown year round as a perennial.
Natural: Full sun. Partial shade during hotter spells.
Artificial: Will grow well indoors under T5 fluorescent lamps or HIDs. Keep T5s a foot above plants and HIDs 2–4 feet above plants to avoid burning.
Soil: Prefers loamy, well-drained soil. A pH of between 5.5–7.5 will keep plants healthy and nourished.
Soilless: Germinate seeds in a soilless mix such as perlite, vermiculite, or coco coir.
Hydroponics: Will thrive in a hydroponic media bed system.
Aeroponics: Will thrive in an aeroponic system.
Water: Requires moderate to high levels of water. In earlier stages of growth, plants should be watered regularly enough to keep soil moist, but make sure that soil is well-drained to avoid root rot. Once plants have become established, they can tolerate slightly dry soil.
Nutrients: Is a light feeder and does not require very rich soil. If soil is highly acidic, add limestone to neutralize.
Pruning: A hearty plant, fennel does not require a great deal of pruning to keep up its productivity. That said, plants that are grown as a perennial can be cut back by removing old or weak-looking branches in early spring to encourage new growth.
Deficiency(s): This plant tends to be susceptible to tip burn often caused by a calcium deficiency or lack of water. To remedy this problem, amend soil with limestone, eggshells, or gypsum and increase watering if natural precipitation is sparse.
Companions: Fennel’s chemical output make it a poor companion plant for any other plant species. Dill, as the exception to this rule, could be planted with fennel, but unwanted cross pollination might take place between the two. Keep fennel in its own space, downwind from other plants, or in its own container.
Harvest: Leaves and stems may be harvested as soon as they begin to mature by cutting off sprigs as needed, or the whole plant may be harvested by cutting the main stalk just above the soil surface. Seeds may be harvested once they turn grey/green. They may be harvested up until they turn dark brown but will likely fall to the ground before you are able to collect them, so be sure to keep an eye on the progress of your plant if you are planning to store seed.
Storage: Leaves are best used fresh but may also be dried. Leaves can be dried by bunching stalks together and hanging upside down in a warm, dry location. Keep leaves away from direct light to avoid fading. Seeds can be harvested by placing seed heads in a paper bag and hanging upside down. Shake the seeds out when they have dried and store in a sealed container.
Fun Fact: In Greek legend, Prometheus brought fire to man by stealing it from the lightning bolt of Zeus, the great king of the Gods. In order to transport the fire to earth, Prometheus stored it in the stalk of a fennel plant. Talk about the power of plants!
Preserve: Seeds and leaves may be dried by keeping in a dry, dark place. Aside from hanging upside down to dry, leaves may also be placed in the oven on the lowest temperature setting until completely dry.
Prepare: Frequently eaten raw in the US, many Mediterranean recipes also add fennel seeds, leaves or bulbs to coals when grilling meats or fish to add a distinctive licorice-type flavor. Fennel can also be sautéed, added to stir fries, or used to infuse broths. The leaves may also be used dried in teas.
Nutritional: High in dietary fiber, vitamin C and potassium. The seeds in particular are high in manganese, iron, calcium, and magnesium.
Medicinal: Traditional medicine has used fennel for various ailments, but fennel is most commonly cited as being used in ancient cultures for improving eye sight. Today, there is strong evidence to suggest that fennel is effective in calming the stomach and reducing symptoms of indigestion. Some evidence also exists that supports the claim that fennel can assist in alleviating menstrual cramps and regulating women’s periods.
Warnings: Evidence for the benefits of using fennel vary greatly, particularly for pregnant women. While some sources cite fennel as being effective at treating colic and improving breast-milk production, other sources simultaneously note that it may be toxic to very young children. Consult your physician prior to consuming fennel or feeding fennel to children.
Be sure to save some seeds from your fennel plant and room for dessert for these tasty Almond and Fennel Biscottis.