How to Grow Fennel: A Toronto Master Gardeners Guide

Fennel (Foeniculum vulgare). Fennel, like its close relative dill, is grown for its frond-like leaves, which are harvested and used fresh (especially in fish dishes) and for its seeds, which have many uses in the kitchen. All fennel varieties are attractive — in particular bronze-leaved fennel (Foeniculum vulgare ‘Purpureum’) — and lend themselves to being incorporated into a mixed bed.  Fennel flowers attract many beneficial insects.

Cultivation: Fennel is a tender perennial grown in Ontario as an annual. Since it does not transplant well, sow seeds directly in the ground once the soil warms up (15°C) or in the same pots where it is to be grown. Fennel thrives in full sun and soil rich with organic matter. Once established, it is drought tolerant. Fennel may reach one metre or more in height, so it should be placed with this in mind.

Leaves can be harvested as needed as soon as there is sufficient growth, and continue through to autumn. Seeds can be dried for winter use. Fennel self-seeds readily and can become an unwelcome weed unless the seed heads are removed.

Fennel is prone to aphid infestation and also attracts black swallowtail caterpillars, which may temporarily cause significant damage.

Florence Fennel (Foeniculum vulgare var. dulce) is grown for its swollen ‘bulb’ rather than its fronds and seeds and is eaten as a vegetable.

Disclaimer: Toronto Master Gardeners does not advise or recommend herbs for medicinal or health use. Any information in the recommended resources should be regarded as being for educational purposes only and should not be considered as a recommendation or an endorsement of any medical or health treatment.

 For more information:

(MDC) Missouri Department of Conservation:https://nature.mdc.mo.gov/discover-nature/field-guide/black-swallowtail-parsnip-swallowtail

Richters  https://www.richters.com/show.cgi?page=QandA/Growing/19990207-1.html

OMAFRA http://www.omafra.gov.on.ca/CropOp/en/spec_veg/other_spec_veg/ffen.html

West Coast Seeds https://www.westcoastseeds.com/blogs/how-to-grow/grow-fennel

University of Illinois Extension, Growing Herbs – Fennel https://web.extension.illinois.edu/herbs/fennel.cfm

Fennel: https://www.rhs.org.uk/advice/grow-your-own/herbs/fennel

Date revised: December 2021

Prepared by the Toronto Master Gardeners, these Gardening Guides provide introductory information on a variety of gardening topics.  Toronto Master Gardeners are part of a large, international volunteer community committed to providing the public with horticultural information, education and inspiration.  Our goal is to help Toronto residents use safe, effective, proven and sustainable horticultural practices to create gardens, landscapes and communities that are both vibrant and healthy.

Statement on Invasive Plants: When choosing plants, avoid invasive plants, which can spread quickly and dominate gardens.  Invasive plants are sold by nurseries, big box stores or even at community plant sales.  Invasives may already be present in your garden.  They can invade gardens by spreading from under a neighbour’s fence or may be transported by wildlife.  For beautiful, sustainable options to invasive plants, see the Ontario Invasive Plant Council’s “Grow Me Instead – Beautiful Non-Invasive Plants for your Garden” at https://www.ontarioinvasiveplants.ca/resources/grow-me-instead/before purchasing or accepting “gifts” of plants.

Statement on Home Remedies: The Toronto Master Gardeners do not recommend home remedies, as these have not been proven effective through scientific investigation, and may even damage other living organisms in the soil or plants in your garden.  There are other garden friendly options you can use.

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