Gadenin日本語Get the appJudging when a bulb is ready
A Florence fennel bulb is ready when it is about the size of a tennis ball, roughly three inches (7.5 cm) across at the widest point, firm when squeezed from the sides, and still smooth-skinned. That is usually twelve to fourteen weeks from sowing. Size alone is not the test; a bulb that has stopped swelling and started to feel fibrous is past its point regardless of how big it is.
The window is short. From usable size, you have roughly two weeks before the outer layers turn stringy, the flavor becomes harsh, and the plant starts to extend a flower stem. Once a stem is visibly rising from the center, the bulb is finished as a vegetable. This is exactly why short successional sowings matter more for fennel than for most crops.
Do not wait for a bulb to get larger if the plant has already been checked. A bulb that has stalled at golf-ball size after a dry spell will not resume; harvest it small and use it, because leaving it in the ground only invites splitting and bolting.
| Sign | What it tells you | Action |
|---|---|---|
| 3 inches (7.5 cm) across, firm, smooth | At its best | Cut now |
| Outer layer dull and ribbed, slightly loose | Just past peak, still good cooked | Cut within a few days, braise rather than eat raw |
| Vertical splits down the side | Growth restarted after drought | Cut immediately, trim the split layer off |
| Central stem extending upward | Bolting, bulb will now go woody | Cut and use the heart, leave the rest for fronds |
| Base flattened and elongating, no swelling | Never going to bulb | Treat as a leaf and seed plant |
| Brown soft patch at the collar | Rot from soil packed into the crown | Harvest, cut the damage away, do not store |
Cut high and get a second crop
Most people pull the whole plant, root and all. Cutting instead is better. Slice the bulb off horizontally about an inch (2.5 cm) above the soil, leaving the root and the very base of the crown in the ground. In warm weather that stump pushes out a cluster of slim, tender shoots within two to three weeks, and those shoots are excellent raw in salads or grilled whole.
The second flush is not another bulb, and it will not be. It is a bonus leaf crop from ground you have already prepared, and it costs nothing but leaving the root in. Water the stump as you would the standing crop and it will keep producing until the first hard frost.
Trim the fronds off the harvested bulb straight away and use them separately. Left attached they draw moisture out of the bulb, which goes limp in a day or two. Trimmed and wrapped, a bulb keeps for two to three weeks in the bottom of a refrigerator; unwrapped it dehydrates and softens quickly.
- Cut in the cool of the morning Bulbs lifted in afternoon heat go limp within hours. Morning-cut bulbs are fully turgid and store noticeably better.
- Trim the stems to 2 inches (5 cm) above the bulb Keep a short collar of stem so the layers stay together, and save the frondy tops in a separate bag. Cutting flush into the bulb opens the layers and shortens storage life.
- Leave the root in the ground for regrowth Water the cut stump and mulch around it. Expect a cluster of pencil-thick shoots in two to three weeks, usable at 6 inches (15 cm) tall.
- Do not wash before storing Brush soil off dry and store the bulb whole and unwashed in a loose bag. Washing drives water into the layers and starts rot at the base.
Fronds, and the two seed harvests
Herb fennel gives leaf from about eight weeks after emergence and keeps giving until the plant commits to flowering. Cut whole young stems from the outside of the clump rather than shearing the top, which keeps the plant producing fresh growth from the center. The finest fronds come from plants cut hard in late spring, because the regrowth is soft and dense.
Fennel pollen is the harvest almost nobody takes and it is the most concentrated flavor the plant produces. When the umbels are fully open and bright yellow, cut whole heads in dry weather in the morning, hang them upside down over a tray or in a paper bag for a few days, then shake. The dust that falls is pollen, and a teaspoon of it carries more aroma than a handful of seed.
Seed comes in two useful stages. Green seed, taken when the petals have dropped and the seeds are plump, flat and still green, is soft, sweet and intensely aromatic, and it is used fresh within days rather than stored. Ripe seed is taken when about half the seeds on an umbel have turned gray-brown and the head has begun to dry. Cut whole heads into paper bags, hang them somewhere airy for two weeks, then rub the seed free and clean off the chaff.
Cut ripe seed heads before they shatter, not after. A head left one week too long drops most of its seed on the ground, and that is precisely how a single herb fennel becomes a permanent colony.
What to record at harvest
Fennel is a crop where a short record turns guesswork into a reliable routine. Note the date each Florence fennel batch was sown and the date it was cut, and after two seasons you will know your own sowing-to-harvest interval well enough to time sowings so that bulbs arrive in sequence rather than all at once.
Also record how many bulbs from each batch actually bulbed versus bolted, and which sowing window they came from. Almost everyone finds the same pattern: the batches sown into shortening days succeed and the spring batches do not. Seeing it written in your own notes is what finally changes the sowing habit.
For herb fennel, note the date the umbels opened and the date the seed browned. The gap between those two is your window for cutting heads before they shed, and it is typically only two to three weeks. Marking it on a plan means you can cut the seed heads at the right moment instead of discovering seedlings everywhere the following spring.