How To Grow Fennel
A hardy, perennial European herb (Foeniculum vulgare) grown as an annual for its aromatic seeds and fragrant young leaves, both of which are used for flavoring.
In Florence or Sweet Fennel (var. dulce) the greatly enlarged leaf bases form a bulb-like structure 3 to 4 inches in diameter which is called the "apple". When blanched by earthing up it is cooked as a vegetable, but the stalks, resembling anise-flavored celery, can also be eaten raw.
Growing the Herb Fennel
As the seed is slow to sprout, sow it early in spring. The plants require full sunlight but only the simplest culture in any good garden soil.
As the plants grow rapidly, make successional sowings two weeks apart.
Fennel propagates well by seed, but can also be propagated by root and crown division. The seed can also be planted late in fall. When well established, thin plants to stand 8 to 12 inches apart in the row. Plants can also be started indoors and transplanted to the field when 3 or 4 inches tall.
Outdoors, in containers (sow directly in growing pots, do not transplant), and hydroponic cultures.
Fennel usually grows to a height of 18 to 24 inches (45 - 60cm).
Fennel plants should be spaced between 9 and 12 inches (22-30 cm) apart.
Preferred pH Range
Fennel will grow in a relatively wide pH range between 6.1 (mildly acidic) and 8.0 (mildly alkaline) with a preferred range between 7.0 and 8.0.
From seed. Direct sow outdoors in fall or in spring after last frost, Fennel does not transplant well.
Seed Germination Period
Fennel seeds will germinate in approximately 8 to 12 days.
Number of Seeds per Gram
There are between approximately 200 and 300 fennel seeds per gram, depending on variety.
Fennel will grow well in well-drained, deep and moderately fertile soils.
Alternative Growing Media
Soilless potting mixes (Pro-Mix, Sunshine Mix, etc.), perlite, vermiculite, coco peat.
Time From Seed to Saleable Plant
Seed to saleable plant in ten weeks.
Sun & Lighting Requirements
Fennel grown outdoors prefers full sun.
Fennel will grow indoors satisfactorily under high output T5 fluorescent plant lights or high intensity discharge (metal halide or high pressure sodium) plant growing lights. Keep high output fluorescents approximately one foot above the plants, and HID lights between 2 and 4 feet above the plants, depending on wattage. Have an oscillating fan gently stir seedlings for at least 2 hours per day to stimulate a shorter, sturdier, and more natural plant habit.
8a to 10b. Fennel florance grown as annual.
Water regularly, being careful not to overwater. Allow soil to go almost dry between watering, then soak thoroughly.
Potential Plant Pests and Diseases
Fennel can be susceptible to aphids and damping off.
Fennel is only beneficial to dill, and in fact is detrimental to almost every other plant species. Dill is one of a very few known plants that will successfully grow near fennel. Fennel attracts ladybugs, syrphid fly, and tachinid fly and repels aphids.
Fennel is known to attract bees, butterflies and birds. Suitable for containers. Fennel should not be planted near almost all plants, as it can inhibit growth, cause bolting, or actually kill other plants.
Buy Fennel Seeds by Botanical Interests
Heirloom Fennel Florence Finocchio Seeds
Sweet licorice flavored "bulbs" (90 days), and delicately flavored, feathery foliage.
Organic Fennel Florence Perfection Seeds
Larger, more uniform "bulbs" & delicately flavored foliage. Developed for cool, northern climates.