Bulb Fennel: Learn About When And How To Harvest Fennel Bulbs

Stack Of Fennel Bulbs
fresh fennel
(Image credit: Cineberg)

How and when do I harvest my bulb fennel? These are common questions and learning how to harvest fennel bulbs isn't difficult at all. When to harvest fennel bulbs involves a little more, but before we talk about the how and the when, let's make sure we're talking about the right fennel. Fennel is an herb that grows freely in gardens throughout the USDA hardiness zones 5 to 10. The seeds and leaves can be used in a variety of recipes, including flavoring for Italian sausage, and the leaf stalks make a different and wonderful vegetable dish. There are several species available for this use, including Foeniculum vulgare (common fennel), the wild fennel that grows along the roadsides in many parts of the United States. However, if you want to talk about harvesting fennel bulbs for your table, you must plant Florence fennel, a variety of Foeniculum vulgare called Azoricum. In Italy, where this variety has been cultivated for centuries, it is called finocchio. This is the only variety to plant if your goal is harvesting fennel bulbs.

When to Harvest Fennel Bulbs

When do I harvest my bulb fennel? Fennel bulbs take about 12 to 14 weeks from seed to harvest and depend on cool weather for bulb development. If the weather becomes unseasonably warm, all fennel, including finocchio, will bolt, which means it will produce flowers too soon and the bulb won't form. When conditions are right, when to harvest fennel bulbs depends solely on their size. As the bulb grows, measure it with a ruler. The bulb should measure at least 2 inches (5 cm.) in length but no more than 3 inches (8 cm.), about the size of a tennis ball. Harvesting fennel bulbs larger than this will be disappointing as the bulbs tend to get stringy and tough with age. Now that you know when to harvest fennel, let's talk about how to harvest fennel bulbs.

How to Harvest Fennel Bulbs

Use a pair of garden shears or a sharp knife to cut off the plant's stalks and leaves, leaving an inch or two (2.5-5 cm.) at the top of the bulb. Don't discard the greenery! Use it for another dinner as a salad addition or side dish. Carefully clear the soil away from the base of the bulb. If your soil is loose, you can use your hands. If not, use a small garden trowel but try not to nick the bulb. Now, hold the bulb and use a sharp knife to slice the bulb away from the roots. Ta-da! You've just learned how to harvest fennel bulbs! Clean your fennel bulbs with water, and if possible, use them right away while the flavor is most potent. If you can't use the bulbs immediately, store them in an airtight plastic bag in the refrigerator for up to a week. Remember, your bulb will begin to lose flavor as soon as it is cut so use it as quickly as possible. So, when do I harvest my bulb fennel? Right when I need it! I plant my seeds a few at a time so bulbs don't all form at once. I slice them in salads and stir-fry, roast or braise them, and enhance their flavor with mild Italian cheese. They're a different and enjoyable dinnertime treat that can only be experienced during a limited time of year, and that makes them something special. Harvesting fennel bulbs straight from your garden can be a treat for you too!

Jackie Rhoades

Jackie Rhoades began writing for Gardening Know How in 2010.